ARTICLE | doi:10.20944/preprints201812.0337.v1
Subject: Social Sciences, Sociology Keywords: drought; coffee farmers; adaptation; coping strategies; central highlands
Online: 28 December 2018 (07:00:52 CET)
Vietnam is the second largest coffee producer in the world, mostly from the Central Highlands region where water has been becoming a scarce resource. Since 2014, drought has been strongly affecting Central Highlands’ agriculture, particularly coffee production. The drought leads to changes in flowering, ripening and thus harvesting times of coffee. Coffee productivity has reduced about 50 percent. Ultimately, coffee quantity and quality is jeopardized which endangers coffee farmers who occupy 90 per cent of population and their livelihoods mainly rely on coffee. Most of coffee farmers have had to develop alternative strategies to respond to the drought. Based on quantitative and qualitative data collected from 50 coffee households in a community in the Central Highlands, this research has indicated that farmers had to find the ways to adapt as well as to cope with drought. The ways of adaptation and coping were diverse, including short, medium and long-term plans. To strengthen the adaptation and coping strategies of farmers with drought in the short term, it is recommended that authorities provide more technical and financial support to farmers. Furthermore, longer term strategies need to focus on land use planning, investment in irrigation schemes, and consolidated afforestation schemes in appropriate areas.
REVIEW | doi:10.20944/preprints202008.0286.v2
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: elevated CO2; drought; photosynthesis; transpiration rate; stomatal conductance; C4 enzymes; malate; water deficit stress; abscisic acid
Online: 4 July 2022 (08:21:01 CEST)
The changing dynamics in climate is the primary and important determinant of agriculture productivity. The effects of this changing climate on overall productivity in agriculture can be understood when we study the effects of individual components contributing to the changing climate on plants and crops. Elevated CO2 (eCO2) and drought due to high variability in rainfall is one of the important manifestations of the changing climate. There is a considerable amount of literature that addresses climate effects on plant systems from molecules to ecosystems. Of particular interest is the effect of increased CO2 on plants in relation to drought and water stress. As it is known that one of the consistent effects of increased CO2 in the atmosphere is increased photosynthesis, especially in C3 plants, it will be interesting to know the effect of drought in relation to elevated CO2. The potential of elevated CO2 ameliorating the effects of water deficit stress is evident from literature suggesting that these two are agents are brothers in arms protecting the plant from stress rather than partnering in crime, specifically water deficit when in isolation. The possible mechanisms by which this occurs will be discussed in this minireview. Interpreting the effects of short-term and long-term exposure of plants to elevated CO2 in the context of ameliorating the negative impacts of drought will show us the possible ways by which there can be effective adaption to crops in the changing climate scenario.
REVIEW | doi:10.20944/preprints202307.1823.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: drought, food security, short-growing season, rainfed agriculture, subsistence farming
Online: 27 July 2023 (05:47:30 CEST)
In semi-arid regions, climate change has affected crop growing season length and sowing time, potentially causing low yield of the rainfed staple crop pearl millet (Pennisetum glaucum L.) and food insecurity among smallholder farmers. In this study, we used 1994–2023 rainfall data from Namibia's semi-arid North-Central Region (NCR), receiving November–April summer rainfall, to analyze rainfall patterns and trends and their implications on the growing season to propose climate adaptation options for the region. The results revealed high annual and monthly rainfall variabilities, with nonsignificant negative trends for November–February rainfalls, implying a shortening growing season. Furthermore, we determined the effects of sowing date on grain yields of the early-maturing Okashana-2 and local landrace Kantana pearl millet varieties and the optimal sowing window for the region, using data from a two-year split-plot field experiment conducted at the University of Namibia-Ogongo Campus, NCR, during the rainy season. Cubic polynomial regression models were applied to grain yield data sets to predict grain production for any sowing date between January and March. Both varieties produced the highest grain yields under January sowings, with Kantana exhibiting a higher yield potential than Okashana-2. Kantana, sown by 14 January, had a yield advantage of up to 36.0% over Okashana-2, but its yield gradually reduced with delays in sowing. Okashana-2 exhibited higher yield stability across January sowings, surpassing Kantana’s yields by up to 9.4% following the 14 January sowing. We determined the pearl millet optimal sowing window for the NCR from 1–7 and 1–21 January for Kantana and Okashana-2, respectively. These results suggest that co-cultivation of early and late pearl millet varieties and growing early-maturing varieties under delayed seasons could stabilize grain production in northern Namibia and enhance farmers' climate adaptation. Semi-arid agro-region policymakers could utilize this information to adjust local seed systems and extension strategies.
REVIEW | doi:10.20944/preprints202208.0539.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: drought monitoring; drought predictions; drought indices; drought models
Online: 31 August 2022 (08:47:06 CEST)
Drought is considered one of the severest natural disasters and it is difficult to predict it. This review article aimed to display the state of the art of methods used to predict and monitor types of droughts. We examine more than 30 indices and models to identify the strengths and weaknesses of methods and identify gaps remaining in this field. Examples of examined indies are Palmer Drought Severity Index (PDSI), Standardized Precipitation Index (SPI), and Standardized Precipitation Evapotranspiration Index (SPEI). The research found improvement in drought modeling, however, more focus and improvement are required to monitor and predict drought types. It also found that some methods outperform others such as PDSI, SPI, SPEI, EVI, NDVI, NDWI, VCI and TCI.
REVIEW | doi:10.20944/preprints202306.1935.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: drought regime; Southern Africa; drought factors; drought impacts; drought indices
Online: 27 June 2023 (15:33:52 CEST)
Drought is one natural disaster with the greatest impact worldwide. Southern Africa (SA) is susceptible and vulnerable to drought due to its type of climate. In the last four decades, droughts have occurred more frequently, with increasing intensity and impacts on ecosystems, agriculture and health. The work consisted of a systematic literature review on the drought regime’s characteristics in the SA, under current and future climatic conditions, conducted on the Web of Science and Scopus platforms, using the PRISMA2020 methodology, with usual and appropriate inclusion and exclusion criteria to minimize/eliminate the risk of bias, which lead to 41 documents published after the year 2000. The number of publications on the drought regime in SA is still very small. The country with the most drought situations studied is South Africa and the fewer studies are Angola and Namibia. The analysis revealed that the main driver of drought in SA is the ocean-atmosphere interactions including the El Niño Southern Oscillation. The documents used drought indices, evaluating drought descriptors for some regions, but it was not possible to identify one publication that reports the complete study of the drought regime, including the spatial and temporal distribution of all drought descriptors in SA.
ARTICLE | doi:10.20944/preprints202201.0444.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Tonle Sap; meteorological drought; agricultural drought; drought index; drought duration
Online: 28 January 2022 (18:04:28 CET)
Rice production in the Tonle Sap basin is one of the main drivers for economic and social development in Cambodia. The Tonle Sap basin has experienced many different forms of disasters while more attention has been drawn to drought disaster. The objective of this study is to assess the impacts of drought on agriculture and food security through a case study of the Baribo basin, a sub-basin of Tonle Sap basin, Cambodia. Ground observations and satellite-based products were used for drought assessment from 1985 to 2008 which was the period with relatively good data quality. The Standardized Precipitation Index (SPI) and Standard Vegetation Index (SVI) were selected for meteorological and agricultural droughts assessment, correspondingly. Both SPI and SVI consistently suggested that drought is a major natural hazard causing food insecurity in the target basin. The highest drought intensity (DI) and severity (DS) occurred between 1993-1994 and the longest drought duration (DD) occurred between 2002 and 2006. The most severe damage to rice production was in 2004, affecting about 46% of the total cultivated area. The analysis showed that drought duration had a strong relationship with the affected area growing rice as well as food insecurity in the Tonle Sap basin.
ARTICLE | doi:10.20944/preprints201909.0274.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: meteorological drought; effective drought index; bangladesh; frequency of drought
Online: 24 September 2019 (12:17:36 CEST)
This study aims to assess the spatiotemporal characteristics of meteorological droughts in Bangladesh during 1981–2015 using the Effective Drought Index (EDI). Monthly precipitation data for 36 years (1980-2015) obtained from 27 metrological stations, were used in this study. The EDI performance was evaluated for four sub-regions over the country through comparisons with historical drought records identified at the regional scale. Analysis at a regional level showed that EDI could reasonably detect the drought years/events during the study period. The study also revealed that the overall drought severity had increased during the past 35 y; the most significant increasing trend was observed in the central region. The characteristics (severity and duration) of drought were also analysed in terms of spatiotemporal evolution of the frequency of drought events. It was found that the western and central regions of the country are comparatively more vulnerable to drought. Moreover, the southwestern region is more prone to extreme drought, whereas the central region is more prone to severe droughts. In addition, the central region was more prone to extra-long-term droughts, while the coastal areas in the southwestern as well as in the central and north-western region were more prone to long-term droughts. The frequency of droughts in all categories significantly increased during the last quinquennial period (2011 to 2015). The seasonal analysis showed that the north-western areas were prone to extreme droughts during the Kharif (wet) and Rabi (dry) seasons. The central and northern regions were affected by recurring severe droughts in all cropping seasons. Further, the most significant increasing trend of the drought-affected area was observed within the central region, especially during the pre-monsoon (March-May) season. The results of this study can aid policymakers in the development of drought mitigation strategies in the future.
ARTICLE | doi:10.20944/preprints202105.0262.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: common garden; climate change; silver fir; grand fir; Balkan firs; drought stress; provenance test; resilience; climate transfer distance; adaptation
Online: 12 May 2021 (09:52:25 CEST)
Research Highlights: Data of advanced-age provenance tests were reanalyzed applying a new approach, to directly estimate the growth of populations at their original sites under individually generated future climates. The results reveal surprisingly high resilience potential of fir species. Background and Objectives: The growth and survival of silver fir under future climatic scenarios is insufficiently investigated at the xeric limits. The selective signature of past climate determining the current and projected growth was investigated to analyze the prospects of adaptive silviculture and assisted transfer of silver fir populations, and of the introduction of non-autochthonous species. Materials and Methods: Hargreaves’ climatic moisture deficit was selected to model height responses of adult populations. Climatic transfer distance was used to assess the relative drought stress of populations at the test site, relating these to the past conditions to which the populations had adapted. ClimateEU and ClimateWNA pathway RCP8.5 data served to determine individually past, current, and future moisture deficit conditions. Beside silver fir, other fir species from South Europe and the American Northwest were also tested. Results: Drought tolerance profiles explained the responses of transferred provenances and predicted their future performance and survival. Silver fir displayed significant within-species differentiation regarding drought stress response. Applying the assumed drought tolerance limit of 100mm relative moisture deficit, most of the tested silver fir populations seem to survive their projected climate at their origin until the end of the century. Survival is likely also for transferred Balkan fir species and for grand fir populations, but not for the Mediterranean species. Conclusions: The projections are less dramatic than provided by usual field assessments. Some results contradict generally accepted concepts. The method fills the existing gap between experimentally determined adaptive response and the predictions needed for management decisions. It also underscores the unique potential of provenance tests.
ARTICLE | doi:10.20944/preprints201904.0009.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: SMOS; drought index; summer 2018 drought
Online: 1 April 2019 (10:28:40 CEST)
Mapping drought from space using, e.g., surface soil moisture (SSM), has become viable in the last decade. However, state of the art SSM retrieval products suffer from very poor coverage over northern latitudes. In this study, we propose an innovative drought indicator with a wider spatial and temporal coverage than that obtained from satellite SSM retrievals. We evaluate passive microwave brightness temperature observations from the Soil Moisture and Ocean Salinity (SMOS) satellite as a surrogate drought metric, and introduce a Standardized Brightness Temperature Index (STBI). The STBI is validated against drought indices from a land surface data assimilation system (LDAS-Monde), two satellite dervied SSM indices and a standardized precipitation index. Finally, we evaluate the STBI against the before mentioned drought indices in a case study of the 2018 Nordic drought. The STBI is found to be superior to the drought index created from satellite derived SSM in both spatial and temporal coverage over the Nordic region. Our results indicate that when compared to drought indices from precipitation data and a land data assimilation system, the STBI is able to capture the 2018 drought onset, severity and extent. Thus, the STBI index could provide additional information for drought monitoring in regions where the SSM retrieval problem is difficult.
ARTICLE | doi:10.20944/preprints202307.0578.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: abiotic stress; tolerance; salinity; drought; transcriptome; MYB; NFY; HD-ZIP; HSFF
Online: 10 July 2023 (11:06:03 CEST)
In recent years, many studies have reported that several distinct families of transcription factor (TF) genes play crucial roles in the response of plants to abiotic stress. Although some of these families got systematically studied in many species, little knowledge exists about these genes in oil palm (Elaeis guineensis Jacq.). In this study, 20 genes differentially expressed in the leaves of oil palm plants subjected to salinity or drought stress and encoding TFs belonging to four families of TFs - MYB, HD-ZIP, NF-Y, and HSFF - got selected for further characterization. The genes underwent a structural and functional annotation, besides having their RNA-Seq expression profile validated by the qPCR technique, and a correlation analysis of their response under both stresses got performed. The annotation analysis of the promoter region showed the presence of seven cis-acting elements, all already reported to be involved in plants' response to abiotic stress. The structural and functional characterization of the proteins encoded by the selected genes showed that some groups present patterns of conserved regions and are orthologs to genes already linked to salinity or drought resistance in other plant species. It was possible to confirm the RNA-Seq expression profile of 19 genes, only gene 4 showed the opposite response when using qPCR. Through correlation analysis, it was possible to observe a high level of similarity in the behavior of the 20 genes in response to drought or salinity stress, a behavior already reported in other species. The results presented here shed light on the role of 20 TFs in the leaves of young oil palm plants under severe levels of soil salinity or water deprivation. The high level of similarity in the molecular response to both stresses allowed the identification of genes that might grant strategies aiming to develop oil palm plants with a tolerance to both salinity and drought at once.
Subject: Engineering, Automotive Engineering Keywords: drought; drought indices; South Asia; prediction; projection; teleconnection
Online: 1 March 2021 (17:52:21 CET)
South Asian countries experience frequent drought incidents recently, and due to this reason, many scientific studies were carried to explore the drought in South Asia. In this context, we review scientific studies related to drought in South Asia. The study initially identifies the importance of drought-related studies and discusses drought types for South Asian regions. The representative examples of drought events, severity, frequency, and duration in South Asian countries are identified. The Standardized Precipitation Index (SPI) was mostly adopted in South Asian countries to quantify and monitor droughts. Nevertheless, the absence of drought quantification studies in Bhutan and Maldives is of great concern. Future studies to generate a combined drought severity map for the South Asian region are required. Moreover, the drought prediction and projection in the regions is rarely studied. Further, the teleconnection between drought and large-scale atmospheric circulations in the South Asian area has not been discussed in detail in the most scientific literature. Therefore, as a take-home message, there is an urgent need for scientific studies related to drought quantification for some regions in South Asia, prediction and projection of drought for an individual country (or as a region), and drought teleconnection to atmospheric circulation.
REVIEW | doi:10.20944/preprints201812.0145.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: drought stress; drought models; drought tolerance; oxidative stress; phytohormones; polyethylene glycol (PEG); stress markers
Online: 12 December 2018 (12:19:35 CET)
Drought is one of the major stress factors affecting growth and development of plants. In this context, drought-related losses of crop plant productivity impede sustainable agriculture all over the world. In general, plants responses to water deficit by multiple physiological and metabolic adaptations at the molecular, cellular and organism levels. To understand the underlying mechanisms of drought tolerance, adequate stress models and arrays of reliable stress markers are required. Therefore, in this review we comprehensively address currently available models of drought stress, based on culturing plants in soil, hydroponic or agar culture. These experimental setups give access to different aspects of plant response to drought, like decrease of tissue water potential, reduction of stomata conductance and photosynthesis efficiency, accumulation of low-molecular weight solutes (metabolic adjustment) and drought protective proteins. Till now, this pattern of markers was successfully extended to the methods of enzyme chemistry, molecular biology and omics techniques. Thus, conventional tests can be efficiently complemented by determination of phytohormone and reactive oxygen species (ROS) contents, activities of antioxidant enzymes, as well as comprehensive profiling of transcriptome, proteome and metabolome.
ARTICLE | doi:10.20944/preprints202309.0783.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Meteorological drought; Hydrological drought; Drought risk prediction; future climate and land use land cover change scenarios
Online: 13 September 2023 (02:41:43 CEST)
The assessment and prediction of drought risk under future climate change and land use land cover (LULC) scenarios is critically important for drought prevention and mitigation, as it enables a clearer understanding of potential shifts in drought patterns. The primary aim of this study is to evaluate sub-seasonal and seasonal meteorological and hydrological drought hazards across the Yellow River Basin (YRB) under projected future climate conditions and LULC patterns. The BCC-CSM1-1 climate model projections from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset are utilized to represent future climate for 2025-2060 under RCP 4.5 and 8.5 scenarios. The CA-Markov model is employed to predict future LULC distributions. Meteorological and hydrological drought risks across different YRB zones are evaluated through a copula-based risk assessment approach, based on the joint probability distribution of drought duration and severity. The results indicate that sub-seasonal meteorological and hydrological droughts will likely be the primary concern moving forward. Specifically, the upper YRB (zones A, B, C) exhibits greater vulnerability to sub-seasonal meteorological drought, while the Loess Plateau (zones C, E) shows higher susceptibility to sub-seasonal hydrological drought. Moreover, zone F in the downstream region may experience increased seasonal hydrological drought risk due to projected urban expansion in the middle and lower portions of the YRB.
REVIEW | doi:10.20944/preprints202004.0083.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: drought-tolerance characteristics; maize breeding; maize drought tolerance; molecular markers; phenotype; screening of drought-tolerant plants
Online: 7 April 2020 (10:28:30 CEST)
Drought is among the most important abiotic stressors influencing food-crop production worldwide. Currently, drought-tolerant maize materials are rarely used for actual breeding because corn production primarily focuses on heterosis to generate desired varieties. In this article, we reviewed current work on assessing maize drought tolerance. We suggested that the development of enhanced screening techniques must clearly consider the connection between theory and application. We strongly recommend that agricultural scientists focus on translating the results of laboratory experiments into practical methods for improving crop productivity.
ARTICLE | doi:10.20944/preprints201909.0291.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Effective Drought Index (EDI); meteorological drought; climate change; GCMs under RCP scenarios; future drought projections; Bangladesh
Online: 26 September 2019 (03:49:09 CEST)
The impacts of climate change on precipitation and drought characteristics over Bangladesh were examined by using the daily precipitation outputs from 29 bias-corrected general circulation models (GCMs) under the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. A precipitation-based drought estimator, namely, the Effective Drought Index (EDI), was applied to quantify the characteristics of drought events in terms of the severity and duration. The changes in drought characteristics were assessed for the beginning (2010–2039), middle (2040–2069), and end of this century (2070–2099) relative to the 1976–2005 baseline. The GCMs were limited in regard to forecasting the occurrence of future extreme droughts. Overall, the findings showed that the annual precipitation will increase in the 21st century over Bangladesh; the increasing rate was comparatively higher under the RCP8.5 scenario. The highest increase of rainfall is expected to happen over the drought-prone northern region. The general trends of drought frequency, duration, and intensity are likely to decrease in the 21st century over Bangladesh under both RCP scenarios, except for the maximum drought intensity during the beginning of the century, which is projected to increase over the country. The extreme and medium-term drought events did not show any significant changes in the future under both scenarios except for the medium-term droughts, which decreased by 55% compared to the base period during the 2070s under RCP8.5. However, extreme drought days will likely increase in most of the cropping seasons for the different future periods under both scenarios. The spatial distribution of changes in drought characteristics indicates that the drought-vulnerable areas are expected to shift from the northwestern region to the central and the southern region in the future under both scenarios due to the effects of climate change.
ARTICLE | doi:10.20944/preprints201902.0148.v2
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: drought; wildfire; drought index; fuel moisture; California; Nevada; evaporative demand
Online: 1 March 2019 (09:40:59 CET)
Relationships between drought and fire danger indices are examined to 1) incorporate fire risk information into the National Integrated Drought Information System California-Nevada Drought Early Warning System and 2) provide a baseline analysis for application of drought indices into a fire risk management framework. We analyzed four drought indices that incorporate precipitation and evaporative demand (E0) and three fire indices that reflect fuel moisture and potential fire intensity. Seasonally averaged fire danger indices were most strongly correlated to multi-scalar drought indices that use E0 (the Evaporative Demand Drought Index [EDDI] and Standardized Precipitation Evapotranspiration Index [SPEI]) at approximately annual time scales that reflect buildup of antecedent drought conditions. Results indicate that EDDI and SPEI can inform seasonal fire potential outlooks at the beginning of summer. An E0 decomposition case study of conditions prior to the Tubbs Fire in Northern California indicate high E0 (97th percentile) driven predominantly by low humidity signaled increased fire potential several days before the start of the fire. Initial use of EDDI by fire management groups during summer and fall 2018 highlights several value-added applications, including seasonal fire potential outlooks, funding fire severity level requests, and assessing set-up conditions prior to large, explosive fire cases.
REVIEW | doi:10.20944/preprints202102.0466.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Drought stress; Osmotic regulation; LEA protein; ROS; Signaling; Drought-responsive gene
Online: 22 February 2021 (12:38:05 CET)
With the global climate anomalies and the destruction of ecological balance, water shortage has become a serious ecological problem facing all mankind, and drought has become a key factor restricting the development of agricultural production. Therefore, it is essential to study the drought tolerance of crops. On the basis of previous studies, we reviewed the effects of drought stress on plant morphology and physiology, including the changes of external morphology and internal structure of root, stem and leaf, the effects of drought stress on osmotic regulation sub-stances, drought-induced proteins and active oxygen metabolism of plants. In this paper, the main drought stress signals and signal transduction pathways in plants are described, and the functional genes and regulatory genes related to drought stress are listed respectively. We summarize the above aspects in order to provide valuable background knowledge and theoret-ical basis for future agriculture and forestry breeding and cultivation.
REVIEW | doi:10.20944/preprints202308.0476.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: drought stress; wheat genotypes; drought-resistant cultivars; genotype-dependent responses; wheat diversity
Online: 7 August 2023 (07:33:21 CEST)
Drought stress imposes substantial constraints on the growth and production of wheat (Triticum aestivum L.), a globally important cereal crop that is essential for food security. To mitigate these adverse effects, researchers are intensifying their efforts to comprehend how different genotypes respond to drought stress, aiding in the development of sustainable breeding and management strategies. This review summarized past and recent research on genotype-dependent responses of wheat to drought stress, encompassing morphological, physiological, biochemical, molecular, genetic, and epigenetic reactions in plants. Screening of drought-affected features at early developmental stages can provide valuable insights into the adult growth stages that are closely linked to plant productivity. The review underscores the importance of identifying key traits associated with drought resistance, and the potential of leveraging wheat diversity to select cultivars with desirable agronomic characteristics. It also highlights recent advancements in investigating Bulgarian wheat genotypes with varying levels of drought tolerance, specifically in detecting essential features contributing to drought tolerance. Cultivating drought-resistant wheat genotypes and understanding stress stability determinants could markedly contribute to enhancing wheat production and ensuring stable yields under changing climate conditions.
ARTICLE | doi:10.20944/preprints202301.0574.v1
Subject: Biology And Life Sciences, Horticulture Keywords: Drought; Melatonin; Peroxidase; Photosynthesis; Stress
Online: 31 January 2023 (06:21:55 CET)
Melatonin (MT) controls various physiological functions and enhances plant drought tolerance in response to environmental stressors, including water deficit. This study aimed to evaluate the effect of exogenous MT on the morphophysiological attributes of Ranunculus asiaticus under normal and drought conditions. R. asiaticus seedlings were divided into drought-stress and control groups and subjected to foliar application of MT at various concentrations (0, 50, 100, and 200 μM) four times during the study. The drought-stress group exhibited considerably decreased shoot length, leaf number, leaf area, fresh and dry vegetative weights, total chlorophyll and carotenoid contents, and relative water content; delayed emergence of flower stalks; and increased relative electrolyte leakage compared with well-watered plants. Conversely, foliar application of MT notably increased growth parameters compared with their no-treatment counterparts. Foliar treatment with 200 µM MT resulted in the most significant growth response in R. asiaticus under normal or drought-stress conditions. Moreover, compared with no treatment, exogenously applied MT induced the appearance of flower buds and increased relative water and proline contents as well as peroxidase activity while reducing electrolyte leakage. Regarding tolerance index percentages, higher peroxidase and proline contents indicated their suitability for use as markers for drought tolerance, supporting the effective role of exogenous MT in enhancing the adaptability of Ranunculus to drought stress.
ARTICLE | doi:10.20944/preprints201801.0247.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: drought; diversity; oaks; remote sensing
Online: 26 January 2018 (04:52:27 CET)
Drought periods have an adverse impact on the condition of oak stands. Research on different types of ecosystems has confirmed a correlation between plant species diversity and the adverse effects of droughts. The purpose of this study was to investigate the changes which occurred in an oak stand (Krotoszyn Plateau, Poland) under the impact of the summer drought in 2015. We used a method based on remote sensing indices from satellite images in order to detect changes in the vegetation in 2014 and 2015. A positive difference was interpreted as an improvement, whereas a negative one was treated as a deterioration of the stand condition. The Shannon-Wiener species diversity was estimated using an iterative PCA algorithm based on aerial images. We observed a relationship between the species indices of the individual forest divisions and their response to drought. The highest correlation between the index differences and the Shannon-Wiener indices was found for the GNDVI index (+0.74). In addition, correlations were observed between the mean index difference and the percentage shares in the forest divisions of species such as Pinus sylvestris (+0.67 ± 0.08) and Quercus robur (-0.65 ± 0.10). Our results lead us to infer that forest management based on highly diverse habitats is more suitable to meet the challenges in the context of global climatic changes, characterized by increasingly frequent droughts.
ARTICLE | doi:10.20944/preprints202003.0241.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: North and West Africa; drought; DSI; TVDI; NVSWI; spatial correlation; change trend of drought
Online: 15 March 2020 (12:38:03 CET)
North and West Africa are the most vulnerable regions to drought, due to the high variation in monthly precipitation. An accurate and efficient monitoring of drought is essential. In this study, we use TRMM data with remote sensing tools for effective monitoring of drought. The Drought Severity Index (DSI), Temperature Vegetation Drought Index (TVDI), Normalized Difference Vegetation Index (NDVI), and Normalized Vegetation Supply Water Index (NVSWI) are more useful for monitoring the drought over North and West Africa. To classify the areas affected by drought, we used the TRMM spatial maps to verify the TVDI, DSI and NVSWI indexes derived from MODIS. The DSI, TVDI, NVSWI and Monthly Precipitation Anomaly (NPA) indexes with the employ of MODIS-derived ET/PET and NDVI were chosen for monitoring the drought in the study area. The seasonal spatial correlation between the DSI, NPA, NVWSI, NDVI, TVDI and TCI indicates that NVSWI, NDVI and DSI present an excellent monitor of drought indexes. The change trend of drought from 2002 to 2018 was also characterized. The frequency of drought showed a decrease during this period.
ARTICLE | doi:10.20944/preprints202305.1897.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: GmCAMTA; circadian rhythm; development; drought stress
Online: 26 May 2023 (09:14:59 CEST)
The calmodulin-binding transcription activators (CAMTAs) mediate transcriptional regulation of development, growth, and responses to various environmental stresses in plants. To characterize the biological processes of soybean CAMTA (GmCAMTA) family members in response to abiotic stress, we identified 15 GmCAMTA genes from soybean (Glycine max L.) and investigated their roles in the abiotic stress response. The transcriptions of GmCAMTAs exhibited distinct circadian regulation patterns and were expressed differently in response to salt, drought, and cold stresses, except ABA. Interestingly, the expression levels of GmCAMTA2, GmCAMTA8, and GmCAMTA12 were higher in stem tissue than in other soybean tissues. To determine the roles of GmCAMTAs in the regulation of developmental processes and stress responses, we isolated GmCAMTA2 and GmCAMTA8 cDNAs from soybean and generated Arabidopsis overexpressing transgenic plants. The GmCAMTA2-OX and GmCAMTA8-OX plants showed hypersensitivity to drought stress. The water in the leaves of GmCAMTA2-OX and GmCAMTA8-OX plants was lost faster than that in WT plants under drought stress conditions. In addition, stress-responsive genes in the GmCAMTA2-OX and GmCAMTA8-OX plants were down-regulated under drought stress conditions. Our results suggest that GmCAMTA2 and GmCAMTA8 genes are regulated by circadian rhythms and function as negative regulators in development and drought stress responses.
ARTICLE | doi:10.20944/preprints202304.0487.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: drought; shock; agro-climate; agriculture; precipitation
Online: 18 April 2023 (05:01:00 CEST)
Globally and in Hungary, agriculture is one of the most vulnerable sectors to weather and climate extremes. Intense temperature rises, spatial and temporal variations in precipitation, and significant changes in extreme climatological and weather parameters have contributed to changes in the conditions of cropland, crop losses, and crop quality in recent years. The aim of the research is to describe the transformation of the domestic agricultural sector due to the extreme drought shock of 2022 and to explore the adaptation strategies applied. The studies are based on their own agro-climate database and crop data. The results can help smallholders effectively reduce the adverse impacts, thereby increasing their adaptation to similar shocks.
ARTICLE | doi:10.20944/preprints202208.0168.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: drought; institutions; smallholder farmers; water security
Online: 9 August 2022 (03:49:28 CEST)
Disasters such as the 2015-2018 drought in South Africa usually negatively impact agricultural water, especially in smallholder farming systems. This study assessed the availability of irrigation water, performance of irrigation infrastructure, and water governance systems in Genadendal, Western Cape, with a focus on smallholder farmers. Data for streamflow, dam levels, and rainfall were acquired from water institutions and analysed using Microsoft Excel. The performance of the infrastructure and water governance were assessed based on the perceptions of smallholder farmers and key informants. A questionnaire was administered to eight smallholder farmers, followed by a focus group discussion with 15 smallholder farmers. Interviews were conducted with eight key informants who worked in water-related institutions. Qualitative data from the interviews were analysed using thematic content analysis. The study showed adequate agricultural water resources during the 2015-2018 drought period for the smallholder farmers who relied on water from dams. However, smallholder farmers who relied on the Riviersonderend River experienced severe water shortages during the same period. The findings also showed that there was poor performance of irrigation water infrastructure due to inadequate maintenance. Lack of coordination among institutions, insufficient funding, political interference, fragmentation of roles and responsibilities, lack of human resources, and farmers’ lack of participation and commitment in water resources management contributed to the dysfunctionality of irrigation water governance systems, leading to water insecurity. This study recommends adequate funding for the operation and maintenance of infrastructure. Furthermore, water institutions need to support smallholder farmers with training skills in agricultural water management and infrastructure maintenance. Further studies are recommended to quantify the water lost due to the poor performance of water infrastructure and to develop effective water governance in Genadendal.
ARTICLE | doi:10.20944/preprints202202.0113.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: miR408; conserved; drought; N22; miRNA target
Online: 8 February 2022 (13:17:14 CET)
MicroRNAs act as the cardinal post-transcriptional monitors of gene regulatory networks sculpturing the developmental plasticity and stress responses in plants. Single miRNA target several genes and how the transcriptional regulation of miRNA impacts its pool of targets in different tissues and stress conditions is still elusive. The present study investigated the highly conserved and evolving MIR408 family comprehensively by redefining its evolutionary conservation and diversification in plants followed by detailed functional analysis in rice. MIR408 family comprises three dominant mature forms (21 nt) including a distinct monocot variant. Plant MIR408 family can be divided into six groups. miR408 majorly cleave genes belonging to blue copper protein in addition to several other species-specific targets in plants. Screening of 4726 rice accessions identified 22 sequence variants in 1 Kb upstream (15) and MIR408 region leading to the identification of 8 haplotypes (3: Japonica-specific and 5: Indica-specific). miR408-3p follows flag leaf preferential and drought upregulated expression profile in flag leaf and roots of N22 which seems to be regulated by differential fraction of mCs in the precursor region. The active pool of miR408 regulated targets under control and drought conditions is impacted by the tissue type. Comparative expression analysis of miR408/target module under different sets of conditions features 83 targets exhibiting antagonistic expression in rice. Twelve high confidence targets including 4 plantacyanins (OsUCL6, 7, 9 and 30), pirin, OsLPR1, OsCHUP1, OsDOF12, OsBGLU1, glycine rich cell wall, deoxyuridine 5-triphosphate nucleotidohydrolaseand OsERF7 with antagonistic expression under most conditions. Further, over-expression of osa-MIR408 in drought sensitive rice cultivar leads to the massive enhancement of vegetative growth in rice with improved ETR and Y(II) and enhanced the dehydration stress tolerance at seedling stage.
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: GWAS; drought; rapeseed; water loss ratio
Online: 26 September 2020 (14:20:53 CEST)
Rapeseed (Brassica napus) is one of the most important oil crops in the world; however, drought significantly curtails its growth and productivity. Identifying drought-tolerant germplasm is an efficient and low-cost strategy for addressing water shortages. Using water loss ratio (WLR) as an index of drought tolerance, we screened a panel of 265 B. napus lines. We identified eight low-WLR and six high-WLR accessions, which were regarded as drought-tolerant and drought-sensitive, respectively. Further validated these selected accessions at the seedling stage under drought-stress conditions. The drought-tolerant accessions had significantly greater fresh and dry weights under drought stress than the drought sensitive accessions. Using RT-qPCR, we showed that a set of previously reported drought-adaptive marker genes were expressed at higher levels in the drought-tolerant lines than in the drought-sensitive lines. These results indicated that the drought-tolerant genotypes could be identified from natural populations using WLR. Then, we performed a genome-wide association study to identify loci harboring single nucleotide polymorphisms (SNPs). A total of 139 SNPs were significantly associated with the WLR, of which chromosome A10 harbored the largest number. Furthermore, four putative candidate genes were selected by combining the SNP–WLR association results and transcriptional expression data with the changes in drought tolerance. Thus, we have identified two drought-tolerant B. napus cultivars and uncovered genome-wide variation differentiating B. napus lines related to WLR, in addition to providing insights for further research into WLR-related drought mechanisms.
ARTICLE | doi:10.20944/preprints201805.0064.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: finger millet; mycorrhiza; drought; ROS; antioxidant
Online: 3 May 2018 (09:38:17 CEST)
Under abiotic stress conditions, arbuscular mycorrhizal (AM) fungi help plants by improving nutrient and water uptake. Finger millet is an arid crop having soils with poor water holding capacity. Therefore, it is difficult for the plants to obtain water and mineral nutrients from the soil to sustain life. To understand the role of mycorrhizal symbiosis in water and mineral up-take from the soil, we studied the role of Rhizophagus intraradices colonization and its beneficial role for drought stress tolerance in finger millet seedling. Under severe drought stress condition, AM inoculation led to the significant increase in plant growth (7%), phosphorus, and chlorophyll content (29%). Also, the level of osmolytes including proline and soluble sugars were found in higher quantities in AM inoculated seedlings under drought stress. Under water stress, the lipid peroxidation in leaves of mycorrhized seedlings was reduced by 29%. The flavonoid content of roots in AM colonized seedlings was found 16% higher compared to the control, whereas the leaves were accumulated more phenol. Compared to the control, ascorbate level was found to be 25% higher in leaf tissue of AM inoculated seedlings. Moreover, glutathione (GSH) level was increased in mycorrhiza inoculated seedlings with a maximum increment of 182% under severe stress. The results demonstrated that AM provided drought tolerance to the finger millet seedlings through a stronger root system, greater photosynthetic efficiency, a more efficient antioxidant system and improved osmoregulation.
ARTICLE | doi:10.20944/preprints201801.0029.v1
Subject: Engineering, Civil Engineering Keywords: drought; copula; Bayesian network; inflow; reservoir
Online: 5 January 2018 (05:01:45 CET)
Especially for drought periods, the higher the accuracy of reservoir inflow forecasting, the more reliable the water supply from a dam. The article focuses on probabilistic forecasting of seasonal inflow to reservoirs and determines estimates from the probabilistic seasonal inflow according to drought forecast results. The probabilistic seasonal inflow was forecasted by a copula-based Bayesian network employing a Gaussian copula function. Drought forecasting was performed by calculation of the standardized streamflow index value. The calendar year is divided into four seasons; the total inflow volume of water to a reservoir for a season is referred to as the seasonal inflow. Seasonal inflow forecasting curves conforming to drought stages produce estimates of probabilistic seasonal inflow according to the drought forecast results. The forecasted estimates of seasonal inflow were calculated by using the inflow records of Soyanggang and Andong dams in the Republic of Korea. Under the threshold probability of drought occurrence ranging from 50 to 55 %, the forecasted seasonal inflows reasonably matched critical drought records. Combining the drought forecasting with the seasonal inflow forecasting may produce reasonable estimates of drought inflow from the probabilistic forecasting of seasonal inflow to a reservoir.
ARTICLE | doi:10.20944/preprints202306.2042.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: drought; Moran's I index; Mann-Kendall test; urban droughts; standardized precipitation evapotranspiration index; drought characterization; evapotranspiration, GPCC.
Online: 28 June 2023 (13:30:37 CEST)
Against the backdrop of global climate change, the frequency of drought events is increasing, leading to significant impacts on human society and development. Therefore, it is crucial to study the propagation patterns and trends of drought characteristics over a long-time scale. The main objective of this study is to delineate the dynamics of drought characteristics by examining their propagation patterns in China from 1951 to 2020. In this study, precipitation data from meteorological stations across mainland China were used. A comprehensive dataset consisting of 700 stations over the past 70 years was collected and analyzed. To ensure data accuracy, the GPCC database was employed for data correction and gap filling. Long-term drought evolution was assessed using both the SPI-12 and SPEI-12 indices to detect drought characteristics. Two Moran indices were applied to identify propagation patterns, and the MK analysis method along with the Theil-Sen slope estimator were utilized to track historical trends of these indices. The findings of this study reveal the following key results: (i) Based on the SPI-12, the main areas of China that are prone to drought are mostly concentrated around the Hu Huanyong Line. Indicating a tendency towards drying based on the decadal change analysis. (ii) The distribution of drought-prone areas in China, as indicated by the SPEI-12, is extensive and broadly distributed, with a correlation to urbanization and population density. These drought-prone areas are gradually expanding. (iii) Between 2010 and 2011, China experienced the most severe drought event in nearly 70 years, affecting nearly 50% of the country's area with a high degree of severity. This event may be attributed to atmospheric circulation variability, exacerbated by the impact of urbanization on precipitation and drought. (iv) The frequency of drought occurrence in China gradually decreases from south to north, with the northeast and northern regions being less affected. However, areas with less frequent droughts experience longer and more severe drought durations. In conclusion, this study provides valuable insights into the characteristics and propagation patterns of drought in China, offering essential information for the development of effective strategies to mitigate the impacts of drought events.
ARTICLE | doi:10.20944/preprints202309.1030.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Drought; cotton; Root; Shoot; tolerance; water scarcity
Online: 15 September 2023 (05:34:50 CEST)
Cotton is an important plant since it provides raw materials for various in-dustry bracnhes. Even though cotton is generally tolerant of drought, it is af-fected negatively by long-term drought stress. This experiment was conduct-ed according to a completed randomized plots trial design with 3 replications to determine the upland cotton genotype’s reactions against drought under controlled conditions in the 2022 year. All genotypes were watered with 80 mL-1 of water (100% irrigation, Field capacity) until three true leaves ap-peared. After this period water stress was applied at limited irrigation of 75% (60 mL-1), 50% (40 mL-1), and 25% (20 mL-1) of field capacity. After the trial terminated at 52. Days, the cv. G56, elit line G44, G5, and commercial variety G86 genotype, respectively resulted in the highest Root Length (RL), and the G76 genotype resulted in the lowest RL followed by G41 and G35 elite lines. G1 cultivar showed the highest Root Fresh Weight (RFW), followed by G56, G44, G86, G51, and G88, respectively. The lowest RFW was also obtained in elite lines G76 and G41. The third drought morphological marker, the Num-ber of Lateral Roots (NLRs), was the highest in G44, followed by G86, Cv. G56, elite lines G13 and G5 genotype. The lowest NLRs value was obtained in genotype G47 and G76. The highest RDW means was obtained in elite line G5, followed by Cv. G56, elite line G44, G75 and cv. G90, while the lowes RDW mean obtained in elite line G76, G35, and local varieties G20 and G61. In the SL marker, the highest averages were recorded for genotypes G35, G15, G26, G67, and G56, respectively. In the SFW marker, the highest averages were observed in genotypes G15, G52, G60, G31, and G68, respectively. The lowest SL values were observed in genotypes G91, G72, G32, and G22. Simi-larly, the lowest SFW values were found in genotypes G83, G2, G75, and G91. In another shoot drought marker, Shoot Dry Weight (SDW), the highest val-ues were obtained in genotypes G35, G52, G57, G41, and G60, respectively. Conversely, the lowest SDW values were observed in genotypes G65, G91, G4, G20, and G22. In conclusion, the commercial varieties with high averages in roots, namely G86, G56, G88, and G90, and the genotypes G67, G20, G60, and G57 showing tolerance in shoots, are suggested to be potential parent plants for developing cotton varieties resistant to drought. Using the culti-vars found tolerant in the current study as parents in a drought-tolerant vari-ety development Marker-assisted selection (MAS) plant breeding program will increase the chance of success in reaching the target after genetic diversi-ty analyses are performed. It is highly recommended to continue the plant breeding program with the G44, G30, G19, G1, G5, G75, G35, G15, G52, G29, and G76 genotypes which show high tolerance in both root and shoot sys-tems.
ARTICLE | doi:10.20944/preprints202308.1960.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Water use efficiency; Gene expression; Senescence; Drought
Online: 29 August 2023 (13:35:02 CEST)
Water deficit greatly affects global crop growth and productivity, particularly in water-limited environments like upland rice cultivation, leading to reduced grain yield. Plants activate various defense mechanisms during water deficit, involving numerous genes and complex metabolic pathways. Exploring orthologous genes, linked to enhanced drought tolerance, can aid functional validation in target species using genomic data from model organisms. Here, we studied the OsCPK5 gene in upland rice, an AtCPK6 ortholog from A. thaliana, by overexpressing it in the BRSMG Curinga cultivar. Transformants were assessed under two conditions: water deficit applied 79 days after seeding, lasting 14 days, followed by 7 days of irrigation at 80% field capacity. Physiological data and samples were collected at R3, R6, and R8 stages. GM plants consistently exhibited higher OsCPK5 gene expression across stages, peaking during grain filling. During this phase, GM plants displayed reduced stomatal conductance, photosynthetic rate, and increased water use efficiency compared to non-GM plants under drought. GM plants also exhibited higher filled grain percentage in both irrigation conditions. Their drought susceptibility index was 0.9 times lower than NGM plants, and they maintained a higher chlorophyll a/b index, indicating sustained photosynthesis. NGM plants under water deficit exhibited more leaf senescence, while OsCPK5-overexpressing plants retained green leaves. Overall, OsCPK5 overexpression induced diverse drought tolerance mechanisms, hinting at potential for future development of more drought-tolerant rice cultivars.
ARTICLE | doi:10.20944/preprints202307.1848.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: bZIP transcription factor; Hypericum perforatum; Drought stress
Online: 28 July 2023 (10:31:09 CEST)
bZIP transcription factors, basic leucine zipper, play significant roles in plants’ growth and development processes, as well as in response to biological and abiotic stress. Hypericum perforatum is one of the world's top three best-selling herbal medicines, mainly used to treat depression. However, there is no systematic identification or functional analysis of the bZIP gene family in H. perforatum. In this study, 79 HpbZIP genes were identified. Based on phylogenetic analysis, the HpbZIP gene family was divided into ten groups, designated A-I, and S. The physicochemical properties, gene structures, protein conserved motifs, and Gene Ontology enrichments of all HpbZIPs were systematically analyzed. The expression patterns of all genes in different tissues of H. perforatum (root, stem, leaf, and flower) were analyzed by qRT-PCR, revealing the different expression patterns of HpbZIP under abiotic stresses. HpbZIP69 protein is localized in the nucleus. According to the results of the yeast one-hybrid (Y1H) assays, HpbZIP69 can bind to the HpASMT2 (N-Acetylserotonin O-methyltransferase) gene promoter ( G-box cis-element ) to activate its activity. Overexpressing HpbZIP69 transgenic Arabidopsis lines enhanced tolerance to drought. The content of MDA and H2O2 content was significantly decreased, and the activity of superoxide dismutase (SOD) was considerably increased under the drought stress. These results may aid in additional functional studies of HpbZIP transcription factors and cultivating drought-resistant medicinal plants.
ARTICLE | doi:10.20944/preprints202304.0371.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Drought; Gibberellins; HvGAMYB; Light Deprivation; Pollen Development
Online: 17 April 2023 (02:30:16 CEST)
Drought stress inducing pollen sterility can reduce crop yield worldwide. The regulatory crosstalk associated with the effects of drought on pollen formation at the cellular level have not been explored in detail so far. In this study, we performed morphological and cytoembryological analysis of anther perturbations and examined pollen development in two spring barley genotypes that differ in earliness and drought tolerance. The Syrian breeding line CamB (drought-tolerant) and the European cultivar Lubuski (drought-sensitive) were used as experimental materials to analyze the drought-induced changes in yield performance, chlorophyll fluorescence kinetics, the pollen grain micromorphology and ultrastructure during critical stages of plant development. In addition, fluctuations in HvGAMYB expression were studied, as this transcription factor is closely associated with the anthers development. In the experiments, the studied plants were affected by drought, as was confirmed by the analyses of yield performance and chlorophyll fluorescence kinetics. However, contrary to our expectations, the pollen development of plants grown under specific conditions was not severely affected. The results also suggest that growth modification, as well as the perturbation in light distribution, can affect the HvGAMYB expression. This study showed that the duration of the vegetation period can influence plant drought responses and, as a consequence, the processes associated with pollen development as every growth modification changes the dynamics of drought effects as well as the duration of plant exposition to drought.
ARTICLE | doi:10.20944/preprints202207.0403.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Climate Projection; Downscaling; Drought; Runoff; Snow; Wildfire
Online: 26 July 2022 (10:42:21 CEST)
Snowpack loss in midlatitude mountains is ubiquitously projected by Earth system models, though the magnitudes, persistence and time horizons of decline vary. Using daily downscaled hydroclimate and snow projections we examine changes in snow seasonality across the U.S. Pacific Southwest region during a simulated severe 20-year dry spell in the 21st century (2051–2070) developed as part of the 4th California Climate Change Assessment to provide a "stress test" for water resources. Across California’s mountains, substantial declines (30–100% loss) in median peak annual snow water equivalent accompany changes in snow seasonality throughout the region compared to the historic period. We find 80% of historic seasonal snowpacks transition to ephemeral conditions. Subsetting empirical-statistical wildfire projections for California by snow seasonality transition regions indicates a two-to-four-fold increase in burned area, consistent with recent observations of high elevation wildfires following extended drought conditions. By analyzing six of the major California snow-fed river systems we demonstrate snowpack reductions and seasonality transitions result in concomitant declines in annual runoff (47-58% of historic values). The negative impacts to statewide water supply reliability by the projected dry spell will likely be magnified by changes in snowpack seasonality and increased wildfire activity.
REVIEW | doi:10.20944/preprints202202.0014.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: drought stress; reactive oxygen species; climate change
Online: 1 February 2022 (12:53:40 CET)
Each year, the global population and agriculture suffer critical agricultural output losses as a result of severe drought devastation. Physiological drought occurs when plants are unable to extract water from the soil, even though it is available in the root zone. Apart from having a significant effect on plant physiology, drought stress has the effect of reducing crop yield. Drought stress influences plant metabolism both directly and indirectly. Drought stress alters the morpho-anatomical, physiological, and biochemical composition of plants, thereby decreasing transpiration water loss and increasing the efficiency with which plants use their water. Constant water loss through transpiration, combined with previously lost water, results in leaf water deficits. Nonetheless, drought stress has a wide variety of effects, ranging from lesions to confusion. Plant health is harmed when their ability to absorb water and nutrients, interact with their environment, and breathe is harmed. Apart from oxidative damage to plants, it may also result in cell death, which can occur under certain conditions when cells are exposed to their environment. Drought induces a plethora of physiological and molecular changes in plants, the majority of which assist them in adapting to the harsh environment. To mitigate drought's adverse effects, we must first gain a better understanding of how drought affects plant physiology. The purpose of this research is to better understand how drought affects plant development by examining the causes and effects of drought stress.
ARTICLE | doi:10.20944/preprints202201.0337.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Co-composted biochar; drought; NUE; PUE; salinity
Online: 24 January 2022 (09:41:10 CET)
This pot-based study investigated the influence of co-composted wood-derived biochar on lettuce growth performance under salinity and drought stress conditions. Biochar of two particle sizes; > 2 mm and < 1 mm were co-composted with the mixture (1:1 ratio of dry weight) of cow and poultry manures. Co-composted biochars were applied at 5% and 7% rates in soil. Control treatments included the amendment of mixture of biochar with manure in soil. Pots were subjected to slight drought (48-55% water filled pore space (WFPS) of soil) and non-drought conditions (60% WFPS) and under 0 and 1.3 dS m-1 salinity. Results revealed that plants growth performance was significantly better under treatments of co-composted biochar and no salt stress conditions, than when mixture of biochar and manure was applied to soil as non-composted fertilizer. Under no stress condition, small particle-sized co-composted biochar increased root biomass by 786.2% than the large particle-sized co-composted biochar at same application rate. As compared to large-sized co-composted biochar, small sized co-composted biochar at high application rates increased root biomass by 167 – 245% but not leaf biomass under both stress conditions. Small particle-sized co-composted biochar amendment also increased the phosphorus use efficiency (PUE) of lettuce leaves than large particle-sized co-composted biochar under no stress condition. The amendment of small-sized co-composted biochar also increased significantly the concentration of Olsen phosphorus in soil than the amendment of large-particle-sized co-composted biochar. In conclusion, amendment of small particle-sized co-composted biochar has the potential of attenuating salinity and drought stress in lettuce and promoting P cycling in soil.
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Drought; SPEI; Pluvial; Severity; Frequency; Duration; Kenya
Online: 4 February 2020 (15:56:58 CET)
This work examines drought and wet events based on Standardized Precipitation-Evapotranspiration Index (SPEI) over Kenya from 1981 to 2016. Spatiotemporal analysis of dry and wet events is conducted for 3 and 12-month SPEI. The drought incidences were observed during the period 1984, 1987, 2000, 2006, 2009, 2015, and 2016 for SPEI-3 whilst the SPEI-12 demonstrated the manifestation of drought during the year 2000 and 2006. SPEI clearly shows that the wettest period, 1997 and 1998 that coincide with the El Nino event in both time steps. SPEI -3 shows a reduction in moderate drought events while severe and extreme cases were on increase towards the end of the twentieth century. Conversely, SPEI-12 depicts an overall increase in severe drought occurrence over the study location with observed intensity of -1.54 and cumulative frequency of 64 months during the study period. The trend of wet events is upwards in the western and central highlands while the rest of the regions show increase in dry events during the study period. Moreover, moderate dry/wet events predominate whilst extreme events occur least frequent across all grid cells. It is apparent that the study area experiences mild extreme dry events in both categories although moderately severe dry events dominate most parts of the study area. High intensity and frequency of drought is noted in SPEI-3 while least occurrences of extreme events are recorded in SPEI-12. Although drought event prevails across the study area, there is evidence of extreme flood conditions over the recent decades. These findings form a good basis for next step of research that will look at projection of droughts over the study area based on regional climate models.
ARTICLE | doi:10.20944/preprints201702.0085.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: alfalfa; drought; microRNA; small RNA; differential expression
Online: 23 February 2017 (09:50:07 CET)
Alfalfa, an important legume forage, is an ideal crop for sustainable agriculture and a potential bioenergy plant. Drought, one of the most common environmental stresses, substantially affects plants’ growth, development and productivity. MicroRNAs (miRNAs) are newly discovered gene expression regulators that have been linked to several plant stress responses. To elucidate the role of miRNAs in drought stress regulation of alfalfa, a high-throughput sequencing approach was used to analyze 12 small RNA libraries comprising of 4 samples, each with 3 biological replicates. We identified 348 known miRNAs, belonging to 80 miRNA families, from the 12 libraries and 281 novel miRNAs using Mireap software. 18 known miRNAs in roots and 12 known miRNAs in leaves were screened out as drought-responsive miRNAs. Except for miR319d and miR157a which were upregulated under drought stress, the expression pattern of drought-responsive miRNAs were different between roots and leaves in alfalfa. This is the first study discovering miR157a, miR1507, miR3512, miR3630, miR5213, miR5294, miR5368 and miR6173 are drought-responsive miRNAs. Target transcripts of drought-responsive miRNAs were computationally predicted. All 447 target genes for the known miRNAs were predicted using an online tool. This study provides a significant insight on understanding drought-responsive mechanisms of alfalfa.
ARTICLE | doi:10.20944/preprints201610.0013.v1
Subject: Engineering, Civil Engineering Keywords: drought; SPEI; evapotranspiration; Thornthwaite; FAO Penman-Monteith
Online: 6 October 2016 (13:04:49 CEST)
The aim of this study is to analyze the characteristics of drought such as intensity, cumulative curves and trends, based on SPEI (Standardized Precipitation Evapotranspiration Index) at 8 stations in Korea from 1981 to 2010. The traditional SPEI is based on Thornthwaite equation for estimating evapotranspiration; SPEI_th. However, a standard of agricultural water management in Korea suggests FAO Penman-Monteith equation; SPEI_pm. In this study, we analyzed the intensity and trends of drought using SPEI_th and SPEI_pm, respectively, and analyzed the relationship between them. Both of central and southern region, the SPEIs were below -1.0 (moderated drought) for the periods May-August in the representative drought year such as 1988, 2001, and 2008-09. The frequency of drought was higher in southern region than central region. In addition, SPEI_pm showed slightly more intensive drought rather than SPEI_th except for Chuncheon and Gwangju. In 5 stations except for Cheoncheon, Gwangju and Jinju, the cumulative probability that SPEI_pm is below -1.5 was significantly increased from 1981-1995 to 1996-2010. As the results of drought trends, the increasing trend of SPEIs was shown on fall season, and the cumulative probability that SPEI_pm is below -1.5 was also significantly increased.
ARTICLE | doi:10.20944/preprints201811.0476.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: remotely sensed drought indices (RSDIs); Standardized Precipitation Evapotranspiration Index (SPEI); meteorological drought; Skill Score (SS); Yellow River basin (YRB)
Online: 19 November 2018 (17:26:37 CET)
Due to the advantages of wide coverage and continuity, remotely sensed data are widely used for large-scale drought monitoring to compensate the deficiency and discontinuity of meteorological data. However, few researches have focused on the capability of various remotely sensed drought indices (RSDIs) for representing the spatio-temporal variations of the meteorological droughts. In this study, five RSDIs, namely Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI), Modified Temperature Vegetation Dryness Index (MTVDI) and Normalized Vegetation Supply Water Index (NVSWI) were calculated using Moderate Resolution Imaging Spectroradiometer (MODIS) monthly NDVI and LST. The monthly NDVI and LST data were filtered by Savitzky-Golay (S-G) filtering method. Meteorological station-based drought index represented by Standardized Precipitation Evapotranspiration Index (SPEI) was compared with RSDIs. And the dimensionless Skill Score (SS) method was adopted to identify the spatiotemporally optimal RSDIs for presenting the meteorological droughts in the Yellow River basin (YRB) from 2000 to 2015. The results indicated that (1) RSDIs revealed a decreasing trend to the overall YRB consistent with SPEI except for in winter, and different variations of seasonal trends spatially; (2) the optimal RSDIs in spring, summer, autumn and winter were VHI, TCI, MTVDI and VCI, respectively, and the average correlation coefficient between the RSDIs and SPEI was 0.577 (=0.05); (3) different RSDIs have a 0–3 months’ time-lags compared with meteorological drought index.
ARTICLE | doi:10.20944/preprints202306.1859.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Brassica napus; exogenous proline; recovered growth; simulated drought
Online: 27 June 2023 (09:40:28 CEST)
This study was carried out to evaluate the effect of exogenous proline on growth, biochemical responses, and plant recovery of drought-stressed oilseed rape plants after renewed irrigation. The experiment was conducted under controlled laboratory conditions. After 21 days of cultivation, 3-4 leaf stage seedlings were sprayed with proline (1 mM), then subjected to prolonged drought stress for 8 days to achieve a severe water deficit, then irrigation was resumed and recovery was assessed after 4 days. The results show that exogenous application of proline reduced drought-induced growth inhibition of seedlings while maintaining relative water content (RWC) and growth parameters closer to those of irrigated plants. Proline had a positive effect on chlorophyll accumulation and membrane permeability while decreasing ethylene, H2O2, and MDA levels. Moreover, after 4 days of recovery, the H2O2 content of the proline-treated plants was significantly lower (2-fold) and the MDA content was close to that of continuously irrigated plants. Thus, all these biochemical reactions influenced plant survival: after drought + proline treatment, the number of surviving plants was 2 times higher than that of drought-treated plants. The findings show that exogenous proline has antioxidant, osmotic, and growth-promoting properties that improve the drought tolerance of winter oilseed rape plants and is, therefore, beneficial for drought adaptation in oilseed rape.
ARTICLE | doi:10.20944/preprints202306.0986.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: drought; satellite data; Sentinel-2; grassland; mountain; insurance
Online: 14 June 2023 (04:53:50 CEST)
This work estimates yield losses due to drought events in mountain grasslands in north-eastern Italy, laying the groundwork for index-based insurance. Given the high correlation between Leaf Area Index (LAI) and grassland yield, we exploit LAI as a proxy for yield. We estimate LAI by the Sentinel-2 biophysical processor and we compare different gap-filling methods, including time-series interpolation and fusion with Sentinel-1 SAR data. We derive a Forage Production Index (FPI) as the growing season cumulate of the daily product between LAI and a meteorological water stress coefficient. Finally, we calculate the drought index as the anomaly of FPI. The validation of Sentinel-2 LAI with ground measurements showed RMSE of 0.92 [m2 m-2] and R2 of 0.81, on average over all the measurement sites. The comparison between FPI and yield showed R2 of 0.56 at the pixel scale and R2 of 0.74 at the parcel scale. The developed prototype FPI index was used at the end of the growing season of the year 2022 for calculating the payments of an experimental insurance scheme that was proposed to a group of farmers in Trentino-South Tyrol.
REVIEW | doi:10.20944/preprints202212.0210.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Maize; drought; landrace; climate-change; crop genetic resources
Online: 13 December 2022 (01:07:51 CET)
To meet an ever global population's food demand, crop yields must be sustained and increased. Drought, which is getting harsher as a result of global warming, is largely impeding the agricultural productivity. Maize is widely used as food and animal feed in many regions of the world, but its yields are largely effected by drought and heat stress. Historical data on climate change predicts that drought and heat stress becoming major threat for maize cultivation in coming years, which will have huge impact on food security of the world especially in Africa and Asia. Thus there is an immense necessary to develop drought tolerant and climate resilient maize to feed the predicted population of the world. Availability and accessibility of crop genetic resources plays a huge role in development of drought-tolerant maize cultivars. A huge genetic resources of maize, including its landraces and crop wild relatives (CWR) have been reported naturally and many of them have stored in National and International gene banks globally. Conventional breeding methods have been tremendously increased maize yields, but these methods frequently fall short of achieving the demand for improved drought stress resistance. In this article, we have briefly discussed about impact of climate variability on crop production, maize yield losses due to drought, drought tolerance in maize landraces and CWR, and origin and evolution of Mexican landraces. This information may help in utilization of these potential resources in various pre-breeding programs.
ARTICLE | doi:10.20944/preprints202207.0257.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: remote sensing; vegetation coverage; drought; meteorological conditions; Afghanistan
Online: 18 July 2022 (10:04:50 CEST)
The vulnerability of vegetation in the Middle East to meteorological conditions and climate change, especially those leading to drought, is high. Despite the importance of the Amu Darya and Kabul River Basins (ADB and KRB) as a region in which more than 15 million people live, and its vulnerability to global warming, only several studies addressed the issue of the linkage of meteorological parameters on vegetation for the eastern basins of Afghanistan. In this study, data from the Moderate Resolution Imaging Spectroradiometer (MODIS), Global Precipitation Measurement Mission (GPM), and Land Data Assimilation System (GLDAS) to examine the impact of meteorological parameters on vegetation for the eastern basins of Afghanistan for the period from 2000 to 2021. The study utilized several indices, such as Precipitation Condition Index (PCI), Temperature Condition Index (TCI), Soil Moisture Condition Index (SMCI), and Microwave Integrated Drought Index (MIDI). The relationships between meteorological quantities, drought conditions, and vegetation variations were examined by analyzing the anomalies and using regression methods. The results showed that the years 2000, 2001, and 2008 had the lowest vegetation coverage (VC) (56, 56, and 55% of the study area, respectively). On the other hand, the years 2010, 2013, 2016, and 2020 had the highest VC (71, 71, 72, and 72% of the study area, respectively). The trend of the VC for the eastern basins of Afghanistan for the period from 2000 to 2021 was upward. High correlations between VC and soil moisture (R = 0.70, p = 0.0004), and precipitation (R = 0.5, p = 0.008) were found, whereas no significant correlation was found between VC and drought index MIDI. It was revealed that soil moisture, precipitation, land surface temperature, and area under meteorological drought conditions explained 45% of annual VC variability.
ARTICLE | doi:10.20944/preprints202109.0224.v1
Subject: Biology And Life Sciences, Forestry Keywords: Drought; Norway spruce; Heterobasidion; RNA-seq; qRT-PCR
Online: 14 September 2021 (08:19:04 CEST)
The major threats to the sustainable supply of forest tree products are adverse climate, pests and diseases. Climate change, exemplified by increased drought, poses a unique threat to global forest health. This is attributed to the unpredictable behavior of forest pathosystems, which can favor fungal pathogens over the host under persistent drought stress conditions in the future. Currently, the effects of drought on tree resistance against pathogens are hypothetical, thus research is needed to identify these correlations. Norway spruce (Picea abies) is one of the most economically important tree species in Europe, and is considered highly vulnerable to changes in climate. Dedicated experiments to investigate how disturbances will affect the Norway spruce - Heterobasidion sp. pathosystem are important, in order to develop different strategies to limit the spread of H. annosum s.l. under the predicted climate change. Here, we report a transcriptional study to compare Norway spruce gene expressions to evaluate the effects of water availability and the infection of Heterobasidion parviporum. We performed inoculation studies of three-year-old saplings in a greenhouse (purchased from a nursery). Norway spruce saplings were treated in either high (+) or low (-) water groups: high water group received double the water amount than the low water group. RNA was extracted and sequenced. Similarly, we quantified gene expression levels of candidate genes in biotic stress and jasmonic acid (JA) signaling pathways using qRT-PCR, through which we discovered a unique preferential defense response of H. parviporum-infected Norway spruce under drought stress at the molecular level. Disturbances related to water availability, especially low water conditions can have negative effects on the tree host and benefit the infection ability of the pathogens in the host. From our RNA-seq analysis, 114 differentially expressed gene regions were identified between high (+) and low (-) water groups under pathogen attack. None of these gene pathways were identified to be differentially expressed from both non-treated and mock-control treatments between high (+) and low (-) water groups. Finally, only four genes were found to be associated with drought in all treatments.
ARTICLE | doi:10.20944/preprints202109.0096.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Central Asia; GRACE; drought; vegetation; water storage; groundwater
Online: 6 September 2021 (13:15:03 CEST)
With the influences of climate change and human activities, the resources and environment of “One Belt and One Road” are facing severe problems and challenges. This study aims to analyze the temporal and spatial dynamics of the drought environment and the response of vegetation cover to the drought by using drought indicators. Gravity Recovery and Climate Experiment (GRACE) drought severity index (GRACE-DSI) and GRACE water storage deficit index (GRACE-WSDI), were calculated to present hydrological drought. Moreover, based on GRACE, Water-Global Assessment and Prognosis (WaterGAP) model, and Global Land Data Assimilation System (GLDAS) data, the groundwater in Central Asia was retrieved to calculate the groundwater drought index called the GRACE Standardized Groundwater Level Index (GRACE-SGI). The results show that the annual precipitation in Central Asia increased slightly at a rate of 0.39 mm/year (p = 0.82) since 2000, while the temperature increased slightly at a rate of 0.05 ℃/year (p = 0.10). The water storage decreased significantly at -0.59 mm/year (p <0.01) and experienced a decrease-increase-decrease process. During the study period, the arid situation in Central Asia deteriorated, especially in the eastern coast of the Caspian Sea and the Aral Sea basin. From 2007 to 2015, the Central Asian environment was generally arid and suffered from different du-rations and degrees of hydrological and groundwater droughts. The drought indicators (i.e., GRACE-DSI, GRACE-WSDI) and the NDVI showed a significantly positive correlation during the growing season. However, the NDVI of cultivated land and grassland distribution areas in Central Asia showed a strong negative correlation with GRACE-SGI. It is concluded that the drought environment in Central Asia affected the growth of vegetation. The continued deterioration of the arid situation may further stress the ecological system in Central Asia.
ARTICLE | doi:10.20944/preprints202108.0483.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Spatio-temporal; Drought; Climate Change; SPI; RCP; Rakai
Online: 25 August 2021 (10:45:01 CEST)
Drought occurrences in Rakai district take a strange model and it has been rampantly increasing causing reduced income levels for farmers, reduced farm yields, increased food insecurity and migration, wetland degradation, illness and loss of livestock. The purpose of this study was to investigate past and future characteristics of drought due to climate change in Rakai district. Datasets used include dynamically downscaled daily precipitation and temperature data from Coordinated Regional Climate Downscaling Experiment (CORDEX) at 0.44°×0.44° resolution over the Africa domain. R software (Climpact2 package), was used to generate SPI values, Mann Kendall trend test and Inverse Distance Weighting methods were used to examine temporal and spatial drought characteristics respectively. Results depicted more extreme and severe drought conditions for SPI12 under historical compared to SPI3,Kakuto, Kibanda and Lwanda sub counties were the most drought hot spot areas, positive trends of drought patterns for both time scales were observed, though only significant under SPI12. Projected results revealed extreme and severe drought conditions will be observed under RCP8.5 SPI12, and the least will be under RCP8.5 SPI3 and SPI12. Results further reveal that Kakuto, Kibanda, Kiziba, Kacheera, Kyalulangira, Ddwaniro and Lwanda sub counties will be the most drought hot spot sub counties across all time scales. Generally projected results reveals that the district will experience more drought conditions under RCP8.5 compared to RCP4.5 for time scale SPI12 and therefore urgent actions are needed.
Subject: Biology And Life Sciences, Plant Sciences Keywords: untargeted approach; metabolites; drought stress; mulberry, LC-MS
Online: 6 July 2021 (17:23:32 CEST)
Mulberry is an economically significant crop for the sericulture industry worldwide. Stresses such as drought exposure have a significant influence on plant survival. Metabolome directly reflects plant physiological status; thus, a way to assess this impact is to perform a global metabolomic analysis. This study investigated the effect of drought stress on mulberry Yu-711 metabolic balance using a liquid chromatography-mass spectrometry (LC-MS) based on an untargeted metabolomic approach. For this objective, Yu-711 leaves were subjected to two weeks of drought stress treatment and control without drought stress. Multivariate and univariate statistical analyses highlighted numerous differentially-accumulated metabolic elements as a function of time and treatment. Drought stress led to a more differentiated metabolites response than the control. We found that the levels of total lipids and galactolipids, and phospholipids (PC, PA, PE) were significantly altered, producing 48% of the total differentially expressed metabolites. Fatty acyls were the most abundant lipids expressed and decreased considerably by 73.6%. Prenol lipids class of lipids increased in drought leaves. Other classes of metabolites, including polyphenols( flavonoids and cinnamic acid), organic acid (amino acids), carbohydrates, benzenoids, and organoheterocyclic, all had a dynamic trend in response to the drought stress. However, their levels under drought stress generally decreased significantly compared to the control. These results provide an overview of the metabolic profile of the mulberry plant through differentially-accumulated compounds and provide a better understanding of global plant metabolic changes in defense mechanisms.
ARTICLE | doi:10.20944/preprints202010.0001.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Association mapping; chromosomes; drought tolerance; markers, structure; traits
Online: 1 October 2020 (08:40:47 CEST)
The objective of this study were to conduct association mapping for drought tolerance at the seedling stage and yield-related traits. 60 cowpea accessions were used in the study. Single-nucleotide polymorphisms (SNPs) discovered through genotyping by sequencing (GBS) were used for genotyping. Association mapping was conducted using single-marker regression (SMR) in Q Gene, and general linear model (GLM) and mixed linear model (MLM) built in TASSEL. The population of the cowpea accessions were analysed using STRUCTURE 2.3.4 and the peak of delta K in the greenhouse showed seven population types, whereas the peak of delta K in the glasshouse indicated the presence of six population types. One SNP marker, 14083649|F|0-9 was associated with NP with a p value <0.001. Fifty SNP markers were associated with PWT at p <0.001. Four SNP markers, 14074781|F|0-16, 100047392|F|0-36, 14083801|F|0-28 and 100051488|F|0-49 were associated with AVSPD at p <0.001. SNP markers, 14074781|F|0-16, 14083801|F|0-28 and 100051488|F|0-49 were associated with PL at P <0.001. Five SNP markers, 100047392|F|0-36, 14083801|F|0-28, 100072738|F|0-34, 14076881|F|0-49 and 14076881|F|0-49 were associated with PWDTH at p <0.001. The 65 SNP markers identified can be used in cowpea molecular breeding to select for AVSPD, NP, PL, PWDTH, PWT, and RR through marker assisted selection (MAS).
REVIEW | doi:10.20944/preprints202001.0364.v2
Subject: Medicine And Pharmacology, Epidemiology And Infectious Diseases Keywords: 2019-nCoV; SARS-CoV; drought; bat; green light
Online: 4 February 2020 (10:31:47 CET)
The new coronavirus (2019-nCoV) in Wuhan has caused virus outbreaks in many provinces and cities in China, and several neighboring countries were also affected. In recent years, coronavirus several outbreaks around the world were reported, however researchers could not predict its onset. Coincidentally, the birthplace of another coronavirus (SARS-CoV) that causes serious public health problems is also in China. This review compares and analyzes the external environment, natural hosts, intermediate hosts, and susceptible populations when these two coronaviruses occurred. Based on the analysis results, we found that the 2019-nCov virus outbreak in Wuhan was not an accidental phenomenon, but a result of a combination of factors. At the same time, through the conclusions of these analyses, we will be able to get a glimpse of the trajectories of new coronaviruses and curb the virus outbreak in future.
ARTICLE | doi:10.20944/preprints201906.0103.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: chalcone synthase; drought stress; flavonoids; transgenic tobacco; overexpression
Online: 12 June 2019 (05:39:29 CEST)
Flavonoids are major secondary metabolites in plants, which play important roles in maintaining the cellular redox balance in cells. Chalcone synthase (CHS) is the key enzyme in the flavonoids biosynthesis pathway, and has been proved to monitor the changes to drought stress tolerance. In this work, we overexpressed a CHS gene in tobacco (Nicotiana tabacum). The transgenic tobacco plants were more tolerant than the control plants to drought stress. The transcription levels of the key genes involved in the flavonoids pathway and the contents of seven flavonoids were also significantly raised in the transgenic tobacco plants. In addition, overexpression of the CHS gene lead to a lower concentration of the oxidative stress product malondialdehyde. Overall, the NtCHS gene studied in this work was considered as a candidate gene for genetic engineering to enhance drought tolerance of plants and improve response to oxidative stress.
ARTICLE | doi:10.20944/preprints201702.0081.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: reference evapotranspiration; climatic change; drought/wet; Songnen Grassland
Online: 22 February 2017 (16:46:01 CET)
Reference evapotranspiration (ET0) plays an irreplaceable role in regional dry/wet conditions under the background of climate change. Based on the FAO Penman-Monteith method and daily climate variables, ET0 was calculated for 22 stations in and around Songnen Grassland, northeast China, during 1960-2014. The temporal and spatial variations of ET0 and precipitation (P) were comprehensively analyzed at different time scales by using the Mann-Kendall test, Sen’s slope estimator, and linear regression coupling with break trend analysis. Sensitivity analysis was used to detect the key climate parameter attributed to ET0 change. Then, the role of ET0 in regional dry/wet conditions was discussed by analyzing the relationship between ET0, P and aridity index (AI). Results shown a higher ET0 in the southwest and a lower in the northeast, but P was opposite to that of ET0. Evidently decreasing trend of ET0 at different time scales was detected in almost the entire region, and the significant trend mainly distributed in the eastern, northeastern and central. For the whole region, sensitivity analysis indicated decreasing trend of ET0 was primarily attributed to relative humidity and maximum air temperature. The positive contribution of increasing temperature rising to ET0 was offset by the effect of significantly decreasing relative humidity, wind speed and sunshine duration. In addition, the value of ET0 shown higher in drought years and lower in wet years.
ARTICLE | doi:10.20944/preprints202309.0286.v1
Subject: Biology And Life Sciences, Horticulture Keywords: essential oil; enzymatic antioxidants; drought; glutathione; lipid peroxidation; proline
Online: 6 September 2023 (04:25:57 CEST)
As abiotic stress, drought limits plant growth and minimizes productivity. The increased request for valuable essential oil extracted from geranium (Pelargonium graveolens L.) is mainly associated with plant growth, which is adversely affected by drought. Melatonin (MT) has been used to enhance plant growth under abiotic stress, however, its impact to overcome drought stress of aromatic plants including geranium is poorly investigated. In the current investigation, MT application at 100 µM was applied under 100 % (well-watered) or 50 % (drought stress) of FC to verify this role. Drought stress markedly reduced growth parameters, herb yield, and total chlorophyll; however, MT alleviated these effects. In contrast, drought enhanced the essential oil percentage in geranium leaves. Despite the reduction in oil yield caused by drought, MT application mitigated this reduction and improved both oil yield and oil components. Besides, MT treatment enhanced the accumulation of total phenols, glutathione, and proline and improved the activity of ascorbate peroxidase, catalase, and glutathione reductase with possible alleviation of drought-induced oxidative damage. Therefore, it reduced both H2O2 and malondialdehyde accumulation, and finally maintained membrane integrity. Overall, this is the first report that reveals that MT application can improve geranium resistance to drought by enhancing the antioxidant potential and protecting the cell membrane from oxidative damage.
ARTICLE | doi:10.20944/preprints202308.0514.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: abiotic stress; nanoparticles; drought; strawberry; silicon dioxide; tissue culture
Online: 8 August 2023 (05:31:31 CEST)
Drought is an important factor seriously affects agricultural production worldwide. Agricultural practices that can increase resistance to drought are gaining importance. In this study the role of nano-silicon dioxide (NaSiO2) in countering drought stress in invitro strawberry plantlets were investigated. In the experiment, the effects of PEG 6000 concentrations (0, 4, 8%) and NaSiO2 concentrations (0, 50, 100 mg L-1) on invitro strawberry plants were determined. Plantlets treated with PEG 6000 showed reduced vegetative growth parameters, but this decrease was reduced with NaSiO2 application. NaSiO2 at 50 mg L−1 induced the maximum shoot and root fresh weight (1.20 g, 1.24 g, respectively) and length (40.09 mm, 34.26 mm, respectively), leaves number (16.67 pieces/plant) and SPAD index 53.57 among 4% and 8% PEG applications. When the SOD and CAT activities were examined, the results showed that application of NaSiO2 enhancement drought stress tolerance by promoted certain antioxidant response by increasing SOD and catalase (CAT) activities under drought stress. According to the results NaSiO2, limited the devastating impact of drought stress and markedly enhanced all the examined parameters.
ARTICLE | doi:10.20944/preprints202307.0373.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: statistical downscaling; CMIP6; precipitation; drought; climate change; South America
Online: 6 July 2023 (07:42:17 CEST)
Drought events are evident effects of climate change around the globe and yield several socio-economic impacts. Such effects are even more relevant for South America (SA) since different activities essential for the continent, like agriculture and energy generation, depend highly on water resources. Thus, this study aimed to evaluate future changes in precipitation and hydro-logical droughts occurrence in SA through climate projections from eight global climate models (GCMs) of CMIP6. To this end, statistical downscaling was applied to the projections with the Quantile Delta Mapping technique, and the method proved to be efficient in reducing systematic biases and preserving GCMs’ trends. For the following decades, the results show considerable and statistically significant reductions in precipitation over most of SA, especially during the austral spring, with the most intense signal under the SSP5-8.5 forcing scenario. Furthermore, GCMs showed mixed signals about projections of the frequency and intensity of drought events. Still, they indicated agreement regarding the increase in duration and severity of events over all of SA and a substantial proportion of moderate and severe events over most of Brazil during the 21st century. These results can be helpful for better management of water resources by deci-sion-makers and energy planners.
ARTICLE | doi:10.20944/preprints202307.0275.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Crop residues; animal feed; drought; Secale cereale L.; Fertilization
Online: 5 July 2023 (08:45:52 CEST)
The rye (Secale cereale L.) crop shows a high potential to collaborate in the sustainability of high Andean livestock because it supports the agroclimatic conditions and acid soils in the Peruvian Andes. The production of green forage, hay, and grain of the rye crop in acid soils was studied with the use of different levels of phosphorus and potassium fertilization in four local rye ecotypes (CBI-001, CSM-001, CJS-001, and CCE-001). The green forage yield (FV) ranged from 32.35 to 53.62 t ha-1, dry matter from 6.05 to 8.56 t ha-1, and hay from 7.0 to 10.36 t ha-1; nutritional levels ranged from 9.02 % to 13.56 % protein and 6.50 to 7.75 % ash levels, mainly with differences between ecotypes (p<0.05). No differences existed between fertilization levels for the number of stems per plant, and flowering stems per plant, and grains per ear (p>0.05). Also, CBI-001 and CCE-001 were superior with 1868.4 and 1797.8 kg ha-1 of grain, respectively (p=0.0072); the use of 60 kg ha of Nitrogen, 120 kg ha-1 of P2O5 and 80 kg ha-1 of K2O gave higher grain and residue yields. The high nutritional value and yield of the rye ecotypes studied in acid soil conditions and without irrigation can be an alternative for livestock feeding and grain production in the rainy season in the Andes as a dual-purpose crop.
REVIEW | doi:10.20944/preprints202302.0134.v1
Subject: Biology And Life Sciences, Forestry Keywords: planting depth; drought; freeze injury; herbivory; mortality; survival; insects
Online: 7 February 2023 (14:01:52 CET)
Artificial regeneration is successful when high performing seedlings are transported with care to the planting site, stored for a short period in an environment without desiccation or fungal growth, and are planted in a deep hole so roots are in contact with moist soil. One of the requirements for success is the ability to avoid common planting mistakes. Due, in part, to use of container stock plus an increase in rainfall, average 1st year survival of pine seedlings (89%) in the southern United States is about 15% greater now than 45 years ago. However, when survival is less than 50% six months after planting, some landowners seek reimbursement for their loss. Some assume poor seedling quality was the cause without realizing that anaerobic soils or sudden freeze events or shallow planting holes or pruning roots, a lack of rain, or underground insects can kill pines. With a focus on pines planted in the southern United States, we list non-nursery factors that have killed seedlings in North America, Africa and Europe.
ARTICLE | doi:10.20944/preprints202203.0291.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: climate change; drought analysis; statistical corrections; ensemble of scenarios
Online: 22 March 2022 (02:53:39 CET)
Climate change is expected to increase the occurrence of droughts with the hydrology in alpine systems being largely determined by snow dynamics. In this paper we propose a methodology to assess the impact of climate change on both meteorological and hydrological droughts taking into account the dynamics of the snow cover area (SCA). We will also analyse the correlation between these types of droughts. We have generated ensembles of local climate scenarios based on regional climate models (RCMs) representative of potential future conditions. We have considered several sources of uncertainty: different historical climate databases, simulations obtained with several RCMs, and some statistical downscaling techniques. We then used a stochastic weather generator (SWG) to generate multiple climatic series preserving the characteristics of the ensemble scenario. These were simulated within a cellular automata (CA) model to generate multiple SCA future series. They were used to calculate multiple series of meteorological drought indices, the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI)) and a novel hydrological drought index (Standardized Snow Cover Index (SSCI)). A linear correlation analysis was applied to both types of drought to analyse how they propagate and the time delay between them. We applied the proposed methodology to the Sierra Nevada (southern Spain) where we estimated a general increase in meteorological and hydrological drought magnitude and duration for the horizon 2071-2100 under the RCP 8.5 emission scenario. The SCA droughts also revealed a significant increase in drought intensity. The meteorological drought propagation to SCA droughts is reflected in an immediate or short time (1 month), obtaining significant correlations in lower accumulation periods of drought indices (3 and 6 months). This will allow us to obtain information about meteorological drought from SCA deficits and vice versa.
ARTICLE | doi:10.20944/preprints202110.0393.v1
Subject: Physical Sciences, Applied Physics Keywords: Drought indices; SPI; RDI; Climate variables; DrinC; Potwar; Pakistan
Online: 26 October 2021 (15:39:16 CEST)
Drought is treated as a key natural disaster that affects numerous segments of the natural environment and economy throughout the world. Drought indices (DIs) were computed for Potwar region (PR) in Punjab-Pakistan, using DrinC software which are deciles, Standard Precipitation Index (SPI) and Reconnaissance Drought Index (RDI). Drought situation of 12, 9, 6 and 3 months was estimated on temporal basis. DIs obtained by deciles technique showed that for the last 39 years, 8-years are with drought severity in a cycle and are occurring every 2 to 7-years just the once repetitively. The RDI and SPI index showed the analogous trends as of deciles. Though, for RDI and SPI, the extremely dry and severely dry class was merely two years and rest of the drought affected years with respect to deciles were normally and intermediately dry. SPI is better as compared to deciles as the severity is better understood in the context of SPI. Regression analysis revealed that the RDI and SPI indices are mutually interrelated and if first 3 month precipitation is obtainable one can forecast yearly RDI. This investigation is valuable to devise future development plans to contest vulnerable drought incidents, its mitigation and impacts on socio-economic sectors.
ARTICLE | doi:10.20944/preprints202107.0450.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Drought; NDVI; Soil moisture; moisture recycling; land-atmosphere interactions
Online: 20 July 2021 (12:12:28 CEST)
The 2018 summer drought in Europe was particularly extreme in terms of intensity and impact due to the combination of low rainfall and high temperatures. However, it remains unclear how this drought developed in time and space in such an extreme way. In this study we aimed to get a better understanding of the role of land-atmosphere interactions. More specifically, we investigated whether there was a change in water vapor originating from land, if that caused a reduction in rainfall, and by this mechanism possibly the propagation and intensification of the drought in Europe. Our first step was to use remote sensing products for soil moisture content (SMC) and the normalized difference vegetation index (NDVI) to see where the 2018 drought started and how it developed in time and space. Our SMC and NDVI analysis showed that the 2018 drought started to impact the soil and vegetation state in June in Scandinavia and the British Isles. After that it moved towards the West of Europe where it intensified in July and August. In September, it started to decay. In October, drought was observed in southeast Europe as well. Based on the observed patterns we divided Europe into six regions of similar spatiotemporal characteristics of SMC and NDVI. Then, we used a global gridded dataset of the fate of land evaporation (i.e., where it ends up as precipitation) to investigate whether the drought intensification and propagation was impacted by the reduction in water vapor transported from the regions that first experienced the drought. This impact was investigated by identifying the anomalies in the water vapor originating from land recycling, imports and exports within Europe during the spring, summer, and autumn seasons. From these regions we identified four drought regions and investigated the changes in water vapor originating from source regions on the development of drought in those regions. It was found that during the onset phase of the 2018 drought in Europe that the water vapor originating from land played an important role in mitigating the precipitation anomalies as, for example, the share of land evaporation contributing to precipitation increased from 27% (normal years) to 38% (2018) during July in West of Europe. Land evaporation played a minor role in amplifying it during the intensification phase of the drought as the share of land evaporation contribution to precipitation decreased from 23% (normal years) to 21% (2018) during August in West of Europe. These findings are somewhat in contrast to similar studies in other continents that found the land surface to play a strong amplifying role for drought development. Subsequently, we found that the relative increase in the amount of land water vapor originating from eastern half of Europe played a role in delaying the onset and accelerating the decay of the 2018 drought in West of Europe.
ARTICLE | doi:10.20944/preprints202106.0612.v1
Subject: Business, Economics And Management, Accounting And Taxation Keywords: Migration; Northern Triangle of Central America; climate change; drought
Online: 25 June 2021 (09:23:22 CEST)
The worldwide number of migrants has had a rapid increase during the last fifteen years. Despite the extensive research studies that elucidate the increase in migrants' recipient countries, we know little about the relationship between the climate factors and human mobility in the countries of origin. Hence, this study focuses on the effects of weather and the propensity of individuals to leave a territory by measuring the importance of rain precipitation or the lack of it in one of the critical food corridors of Central America, formed by El Salvador, Honduras, and Guatemala. To study the mobility process, we develop a stochastic frontier model; the main result shows a greater propensity to migrate when there is a significant drought event in the place of origin. Some other factors that motivate people to leave their homeland are the effect of other climate events measured through the control system (ENSO), homicide levels, economic performance, and exchange rate. The findings allow differentiating between drought and excess precipitation on a population and mobility to other territories. In addition, these results permit us to derive observable implications of the different effects of flooding and drought and create public policies of prevention, mitigation, and resilience.
ARTICLE | doi:10.20944/preprints202008.0224.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: biomass allocation; drought; irrigation; leaf anatomy; mRNA level; proline
Online: 9 August 2020 (21:53:38 CEST)
Recent climatic changes have resulted in an increased frequency and prolonged periods of drought and strained water resources affecting plant production. We explored the possibility of reducing irrigation in a container nursery and studied the growth response of seedlings of economically important forest trees: broadleaf deciduous angiosperms Fagus sylvatica, Quercus petraea and evergreen conifers Abies alba and Pinus sylvestris. We also studied markers of water stress including modifications of biomass allocation, leaf anatomy, proline accumulation and expression of selected genes. Growth of the broadleaved deciduous species was more sensitive to the reduced water supply than that of conifers. Remarkably, growth of the shade tolerant Abies was not affected. Adjustment of biomass allocations was strongest in P. sylvestris, with a remarkable increase in allocation to roots. In response to water deficit both deciduous species accumulated proline in leaves and produced leaves with shorter palisade cells, reduced vascular tissues and smaller conduit diameters, but not conifers. Relative transcript abundance of a gene encoding a Zn-finger protein in Q. petraea and a gene encoding a pore calcium channel protein 1 in A. alba increased as water deficit increased. These findings suggest that in container nursery, the genetic selection can be initiated by water deficit. Our study shows major differences between functional groups in response to irrigation, with seedlings of evergreen conifers having higher tolerance than the deciduous species. This suggests that major water savings could be achieved by adjusting irrigation regime to functional group or species requirements.
ARTICLE | doi:10.20944/preprints202002.0272.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Bread wheat; terminal drought; GWAS; grain yield; kernel abortion
Online: 19 February 2020 (10:48:02 CET)
Bread wheat (Triticum aestivum L.) is one of the most important cereal crops for food security. Of all the stresses that curtail wheat productivity, drought has the most detrimental effects. Especially terminal drought stress i.e. at the time of flowering imposes a big challenge to sustain grain production. In the current study, 339 pre-breeding lines derived from three-way crosses of exotics x elite lines were evaluated in the irrigated and drought stress environments at Obregon, Mexico for the year 2016 and 2018. Drought significantly reduced yield (Y), spike length (SL), number of grains per spikes (NGS) and thousand kernel weight (TKW) by 46.4, 19.2, 23.5 and 25.9%, respectively in comparison to irrigated conditions. Kernel abortion (KA), highly correlated with Y, increased significantly (11.6%) under drought stress environment. Population structure analysis in this panel revealed three sub-populations and a genome wide linkage disequilibrium (LD) decay was at 2.5 cM. Single marker and haplotypes-based genome wide association study (GWAS) revealed significant associations on three chromosomes; 4A (HB10.7), 2D (HB6.10) and 3B (HB8.12) with Y, SL and TKW, respectively. Likewise, associations on chromosomes 6B (HB17.1) and 3A (HB7.11) were identified for NGS and on 3A (HB7.12) for KA. Five traits i.e. normalized difference vegetation index (NDVI), canopy temperature depression (CTD) days to heading (DTH), NGS, KA were associated at chromosome 3A both under irrigated and drought conditions however, different haplotypes were estimated. Twenty-six SNPs were part of 10 haplotype blocks associated with Y, SL, TKW, NGS and KA. In silico analysis of the associated SNPs/haplotypes showed hits with candidate genes known to confer abiotic stress resistance in model species and crops. Potential candidate genes include those coding for sulfite exporter TauE/SafE family in Arabidopsis thaliana, TBC domain containing protein in Oryza sativa subsp. Japonica and heat shock proteins in Aegilops tauschii subsp. tauschii were revealed. The SNPs linked to the promising genes identified in the study can be used for marker-assisted selection.
ARTICLE | doi:10.20944/preprints201902.0154.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Access, availability, climate change, deforestation, drought, food security, SSA
Online: 18 February 2019 (10:16:03 CET)
Like the rest of the globe, Forests in Sub-Saharan Africa (SSA) continue to play a vital role when it comes to food security from the perspective of forest function of climate regulation, water provision, and soil protection. Nevertheless, most of the recent deforestation practices in various countries indicate that the region could face severe food insecurity in the near future since there are already signs of shortage in food production. This study, therefore, examines deforestation, climate change, and food security nexus in SSA while exploring a wide range of examples of food insecurity in the region. Content analysis and a synthetic literature study were conducted using data from scientific data banks. The study links deforestation, climate change to food security while citing examples from various SSA countries such as Cameroon, Nigeria, Kenya to mention but a few. More so, the study investigates how deforestation contributes to climate change, and how such change directly affects agricultural output and hence food security. Lastly, the study discusses the various implication of deforestation in relation to food security.
ARTICLE | doi:10.20944/preprints201811.0340.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: damaged area; direct economic loss; disaster; drought; extreme precipitation
Online: 15 November 2018 (04:26:41 CET)
Understanding the distribution in drought and floods plays an important role in disaster risk management. The present study aims to explore the trends in the standardized precipitation index and extreme precipitation days in China, as well as to estimate the economic losses they cause. We found that in the Northeast China, northern of North China and northeast of Northwest China were severely affected by drought disasters (average damaged areas were 6.44 million hectares) and the most severe drought trend was located in West China. However, in the north of East China and Central China, the northeastern of the Southwest China was severely affected by flood disasters (average damaged areas were 3.97 million hectares) and the extreme precipitation trend is increasing in the northeastern of the Southwest China. In the Yangtze River basin, there were increasing trends in terms of drought and extreme precipitation, especially in the northeastern of the Southwest China, where accompanied by severe disaster losses. By combining the trends in drought and extreme precipitation days with the distribution of damaged areas, we found that the increasing trend in droughts shifted gradually from north to south, especially in the Southwest China, and the increasing trend in extreme precipitation gradually shifted from south to north.
ARTICLE | doi:10.20944/preprints201612.0074.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: AmRosea1 gene; transcriptome analysis; drought tolerance; salt tolerance; rice
Online: 14 December 2016 (09:16:50 CET)
Ectopic expression of the MYB transcription factor of AmROSEA1 from Antirrhinum majus has been reported to change anthocyanin and other metabolites in several species. In this study, we found that overexpression of AmRosea1 significantly improved the tolerance of transgenic rice to drought and salinity stress. Transcriptome analysis revealed that a considerable amount of stress-related genes were affected by exogenous AmRosea1 during both drought and salinity stress treatments. These affected genes are involved in stress signal transduction, the hormone signal pathway, ion homeostasis and the enzymes that remove peroxides. This work suggests that the AmRosea1 gene is a potential candidate for genetic engineering of crops.
ARTICLE | doi:10.20944/preprints202107.0301.v1
Subject: Engineering, Automotive Engineering Keywords: Deficit volume; drought intensity; drought magnitude; extreme number theorem; Markov chain; moving average smoothing; standardized hydrological index; sequent peak algorithm; reservoir volume.
Online: 13 July 2021 (11:25:59 CEST)
The traditional sequent peak algorithm (SPA) was used to assess the reservoir volume (VR) for comparison with deficit volume, DT, (subscript T representing the return period) obtained from the drought magnitude (DM) based method with draft level set at the mean annual flow on 15 rivers across Canada. At an annual scale, the SPA based estimates were found to be larger with an average of nearly 70% compared to DM based estimates. To ramp up DM based estimates to be in parity with SPA based values, the analysis was carried out through the counting and the analytical procedures involving only the annual SHI (standardized hydrological index, i.e. standardized values of annual flows) sequences. It was found that MA2 or MA3 (moving average of 2 or 3 consecutive values) of SHI sequences were required to match the counted values of DT to VR. Further, the inclusion of mean, as well as the variance of the drought intensity in the analytical procedure, with aforesaid smoothing led DT comparable to VR. The distinctive point in the DM based method is that no assumption is necessary such as the reservoir being full at the beginning of the analysis - as is the case with SPA.
REVIEW | doi:10.20944/preprints202309.1519.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: colchicine; drought stress; legumes; morphological traits; physiological traits; induced polyploidy
Online: 22 September 2023 (06:15:52 CEST)
Legumes play a significant role in the alleviation of food insecurity, maintaining soil fertility and achieving sustainable crop production under adverse environmental conditions. The increased demand in legume production contemplates that attention on the genetic improvement of these crops through various means such as genetic engineering and mutation breeding should take a centre stage in global agriculture. Therefore, this paper provides succinct analysis of currently available literature on morphological and physiological traits in polyploidised leguminous plants to counter the adverse effects of drought stress. The effects of colchicine on various morphological and physiological traits of polyploidised legumes compared to their diploid counterparts were examined. Numerous reports revealed variations in these traits such as improved root and shoot growth, plant biomass, chloroplastidic content, protein, RNA and DNA. The differences observed were also associated with the strong relationship between plant ploidy-induction and colchicine application. Furthermore, the analysis indicated that polyploidisation remains dose-dependent, and may be achievable at a shorter space of time as this antimitotic chemical interferes with chromosome separations in somatic plant cells. The efficiency of this process also depends on the advancement of treatment conditions (in vitro, in vivo or ex vitro) and successful regeneration of polyploidised plants for adaptation under drought stress conditions. As such, the improvement in metabolite profile and other essential growth characteristics serves as a clear indication that induced polyploidy needs to be further explored to confer resilience to environmental stress, and improve crop yield under drought stress conditions in leguminous plants.
ARTICLE | doi:10.20944/preprints202309.1197.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Automation; Triticum aestivum; gas exchange; drought tolerance; high-throughput; Cerrado
Online: 19 September 2023 (05:47:28 CEST)
Selecting drought-tolerant and more water-efficient wheat genotypes is a research priority, spe-cifically in regions with irregular rainfall or areas where climate change is expected to result in reduced water availability. The objective of this work was to use high-throughput measurements with morphophysiological traits to characterize wheat genotypes in relation to water stress. Field experiments were conducted from May to September 2018 and 2019, using a sprinkler bar irriga-tion system to control water availability to eighteen wheat genotypes: BRS 254; BRS 264; CPAC 01019; CPAC 01047; CPAC 07258; CPAC 08318; CPAC 9110; BRS 394 (irrigated biotypes) and Aliança; BR 18_Terena; BRS 404; MGS Brilhante; PF 020037; PF 020062; PF 120337; PF 100368; PF 080492; TBIO Sintonia (rainfed biotypes). The water regimes varied from 22 to 100% of the crop evapotranspiration replacement. Water stress negatively affected gas exchange, vegetation indices and grain yield. High throughput variables TCARI, NDVI, OSAVI, SAVI, PRI, NDRE and GNDVI had higher correlation with yield and morphophysiological measurements. The drought re-sistance index indicated that genotypes Aliança BRS 254, BRS 404, CPAC 01019, PF 020062, and PF 080492 were more drought tolerant.
ARTICLE | doi:10.20944/preprints202308.0236.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Climate Change, Water Resources, SPI, SGI, WEAP, Ziz watershed, Drought
Online: 2 August 2023 (14:42:28 CEST)
water resources in Morocco have been severely influenced by climate change (CC) and pro-longed drought, particularly, in the pre-Saharan zone. The Tafilalet region faces increasing pres-sure due to high demographic growth, increased demand for water, excessive groundwater con-sumption, and investment in agriculture. Using the Water Evaluation and Planning System (WEAP), this study assessed land cover and elevation and created future scenarios using the Standard Precipitation Index (SPI) and Standard Groundwater Level Index (SGI) to monitor hy-droclimate drought conditions in the Ziz watershed from 1989 to 2022. Results show decreasing precipitation, particularly from 2010-2020, with the last four years being the most challenging (SPI<-2). SPI and SGI have a high correlation, suggesting precipitation impacts groundwater in-dicators. Future scenarios predict a high risk of CC, with a 30% decrease in annual precipitation accumulation by 2100 under the optimistic scenario SSP126. Minimum temperature is expected to increase by 1.08°C (SSP126) and 2.61°C (SSP585), and maximum temperature by 1.05°C (SSP126) and 2.93°C (SSP585). Keywords: Climate Change, Water Resources, SPI, SGI, WEAP, Ziz watershed, Drought
ARTICLE | doi:10.20944/preprints202307.0178.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: wild barley; (Hordeum spontaneum L.),; drought and salinity; transcriptome analysis
Online: 4 July 2023 (09:52:45 CEST)
Drought and salinity are among the most important abiotic stress factors that limit the productivity in economically important plants. Although genes from wild relatives or unadapted germplasm have often been used for stress tolerance breeding, only few studies have examined wild relatives to understand the genetic and molecular basis of stress tolerance. In this study, we monitored the changes in gene expression profiles of leaf and root tissues of two wild barleys (Hordeum spontaneum L.) accessions from Israel after treatment with salt (NaCl) and drought (PEG) stress. We identified a total of 641 differentially expressed genes across 24 conditions (2 accessions, 2 stress conditions, 2 tissues and 3 time points). Our gene expression analyses revealed large numbers of differentially expressed genes in different accessions by different stress treatments. In addition, the number of genes altered in the leaves of stress-exposed plants of both genotypes was higher than those altered in the roots. Interestingly, there was a relatively little overlap between the leaf and the root stress-responsive gene expression patterns, suggesting that different stress-associated processes might be operating in these tissues during stress adaptation. Overall, our results revealed a number of candidate genes and plant processes associated with stress tolerance in wild barley. Wild barley would be a useful source of new genetic variation for drought and salt stress tolerance. Our results could provide new insights into the mechanisms of drought and salt stress tolerance in wild barley and should be useful for genetic improvement of salt-drought tolerance in cultivated barley.
ARTICLE | doi:10.20944/preprints202306.0274.v1
Subject: Social Sciences, Geography, Planning And Development Keywords: participative policy; drought; floods; risk-management; climate change; resilience; Mexico
Online: 5 June 2023 (08:37:57 CEST)
Abstract: Floods can be defined as one of the most frequent and destructive disasters, that cause significant damage to people, while droughts present significant challenges in first place to most vulnerable communities. In consequence, state public policies are essential to manage the risk in the face of both phenomena and contribute to the construction of resilient communities. As a request of the National Water Commission of Mexico (CONAGUA) for the Regional Water Plan (PHR), we designed and applied a methodology based on virtual consultation fora in conjunction with digital survey tools to understand the population's perception of these phenomena. The workshops were organized in the five municipalities of Baja California Sur. Then, we performed an interdisciplinary analysis that combines hydrological considerations with the most critical social, economic, environmental, and law components, applying the PESTEL analysis. The results indicate that there is a clear and widespread awareness that floods and droughts increase the risk to the livelihoods of the population; however, there are deficiencies in different areas, which complicates risk management. Timely information and the inclusion of communities in mitigation and adaptation proposals would allow for achieving more successful cases with the efforts to minimize vulnerabilities and increase the resilience of the population in the face of a changing climate. This must be a collaborative work of the entire society, governmental, social, and private stakeholders.
ARTICLE | doi:10.20944/preprints202305.2167.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: biochar; salinity; drought; tomato; water; irrigation; growth; fruit; yield; photosynthesis.
Online: 31 May 2023 (03:51:43 CEST)
The use of saline water under drought conditions is critical for sustainable agricultural development in arid regions. Biochar used as a soil amendment to enhance soil properties such as water-holding capacity and the source of nutrition elements of plants. Therefore, the experiment was conducted to evaluate the effects of biochar application on the morpho-physiological traits and yield of tomatoes under combined salinity and drought stress into greenhouses. There were 16 treatments consist two water quality fresh and saline (0.9 and 2.3 dS m-1), three deficit irrigation levels (DI) 80, 60, and 40% addition 100% of ETc, and biochar application by rate 5% (BC5%) (w/w) and untreated soil (BC0%). The results indicated that the salinity and water deficit negatively affected morphological, physiological, and yield traits. In contrast, the application of biochar improved all traits. The interaction between biochar and saline water leads to decreased vegetative growth indices, leaf gas exchange, relative water content of leaves (LRWC), photosynthetic pigments, and yield, especially with the water supply deficit (60 and 40% ETc), where the yield decreased by 42.48% under the highest water deficit at 40% ETc compared to the control. The addition of biochar with freshwater led to significantly increased of vegetative growth, physiological, yield, WUE, and less proline content under all various water treatments compared to untreated soil. In general, biochar combined with DI and freshwater could be improve morpho-physiological attributes, to sustain the growth of tomato plants, and increase productivity in arid and semi-arid regions.
ARTICLE | doi:10.20944/preprints202110.0154.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: arid and semi-arid; afforestation; desertification; drought effects; compost fertilizer
Online: 11 October 2021 (10:49:33 CEST)
Desertification is impeding the implementation of reforestation efforts in Mongolia. Many of these efforts have been unsuccessful due to lack of technical knowledge on water and nutrient management strategies, limited financial support, and short-lived rainfall events. We investigated the effects of irrigation and fertilization on the morpho-physiological traits of Populus sibirica Hort. Ex Tausch and Ulmus pumila L. and to suggest irrigation and fertilization strategies for reforestation. Different irrigation and fertilizer treatments were applied: no irrigation, 2 L h-1, 4 L h-1 and 8 L h-1 of water; no fertilizer, 2 L h-1 + NPK, 4 L h-1 + NPK, and 8 L h-1 + NPK; and no compost, 2 L h-1 + compost, 4 L h-1 + compost, and 8 L h-1 + compost. The leaf area (LA) and specific leaf area (SLA) of both species responded positively to 4 L h-1 and/or 8 L h-1. Results also showed that the addition of either NPK or compost to 4 L h-1 and/or 8 L h-1 irrigation resulted in a higher LA, SLA, and leaf biomass (LB). Total chlorophyll content decreased with irrigation in both species. The same pattern was detected when a higher amount of irrigation was combined with fertilizers. Lastly, we found that both diurnal and seasonal leaf water potential of plants grown in 4 L h-1 and/or 8 L h-1 were significantly higher than in control plots. Therefore, 4 L h-1 and/or 8 L h-1 with either NPK or compost has shown to be the optimal irrigation and fertilization strategy for the species in an arid and semi-arid region of Mongolia. Results should provide us with a better understanding of tree responses to varying amounts of irrigation with or without fertilizer in pursuit of sustainable forest management in arid and semi-arid ecosystems.
ARTICLE | doi:10.20944/preprints202110.0062.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Bioinformatics analysis; Drought stress; Gene expression; Physiological parameters; Tomato; Transcriptome.
Online: 4 October 2021 (15:01:07 CEST)
Identification of the differentially-expressed genes is important for clarification of the complex molecular mechanisms under drought conditions. In this experiment, transcriptome profiles of sensitive and tolerant tomato genotypes under drought stress were analyzed. Three up-regulated genes were selected, included CAB3 (Chlorophyll a-b binding protein3), SAMDC (S-adenosylmethionine decarboxylase proenzyme), and ACS9 (1-aminocyclopropane-1-carboxylate synthase 9). After bioinformatics analysis, tomato genotypes were subjected to drought stress and gene expression was determined using Real-Time-PCR. Physiological parameters of genotypes were also measured by spectrophotometer-based methods. According to the results, these three genes play a key role in stress tolerance. Expression of the CAB3 gene in both sensitive and tolerant genotypes was not significantly different compared to the control, but the SAMDC gene decreased in both genotypes and the ACS9 gene decreased in sensitive genotype and increased in tolerant genotype. The physiological analysis also showed that under stress conditions, the photosynthetic system of the plant was disrupted and the chlorophyll content was reduced, but, proline content and antioxidant enzymes activity increased, in which their quantity in the tolerant genotype was significantly higher than sensitive. Under drought stress, due to damage to the lipid membrane, Malondialdehyde content also increased, in which the sensitive genotype was more affected.
ARTICLE | doi:10.20944/preprints202103.0102.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: Al Zaytun, Climate change, Drought, Islamic perspective, Plant species, Reservoir
Online: 2 March 2021 (15:58:41 CET)
The drought is one of all phenomena at local to a global scale that caused climate change impacts, alongside it also the human activities related, which were deforested and land use changed that caused to ecological disturbance, which one is hydrological changes. Hence, it’s a lot of lost productivity, chiefly to farming land aspects and the other, so the land restoration by reforestation is needed in framework to water cycle (hydrology) process kindly. The aim of this research has identified and analyzed ecological restoration to ecosystem services, chiefly in wastewater management (treatment) to conservation, especially in Al Zaytun areas (Pesantren), so observing and in-depth individual interview (with some of personage and pesantren of boards) is one method that used to data collected, alongside land survey management to classified type development in Al Zaytun areas. The result of this research revealed that Al Zaytun successfully in water management to conservation by wastewater treated management by Eichhornia crassipes (Enceng gondok), afterward to the reservoir as water saved development. Those conservation types considered capability in reviving to ecological systems to ecosystem services increased kindly, alongside to land restoration by some of the plant species or trees to grow and developed in which Tectona grandis L. f is more dominantly and it's favorite because of investment economic that advantage based on ecological perspective. These were type management that did by Al Zaytun, alongside its able in coping to both drought and climate change impacts kindly and adaptively, and of course, it’s part of an obligation as the follower’s Islam religion in preserving and maintaining natural resources, chiefly to water resources.
ARTICLE | doi:10.20944/preprints201906.0054.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Groundwater; Climate resilience; Deep wells, Deep aquifers, Drought, Somali, Ethiopia
Online: 7 June 2019 (12:03:05 CEST)
Groundwater is the most extracted raw material in the world with global annual withdrawal rates of 800–1500 km3/year. In East and Southern Africa, 70 % of the population are reliant on shallow groundwater as their primary drinking water source. With increased population growth, intensification of agriculture and industrialization, conflicting demands on groundwater present a challenge to achieve the Sustainable Development Goals (6,3,11,12,15). Between 2015 and 2018, the Horn of Africa was affected by a series of climatic induced events, namely El Nino, La Nina and the Indian Ocean Diopole. These events modified the variability of rainfall patterns and resulted in long periods of low rainfall, low recharge and high evapotranspiration. As a result, shallow aquifers in alluvial deposits of Somali region have low yields and produce brackish and saline water. That situation prompted humanitarian water professionals to finance the transportation of water from selected locations with high groundwater potential through water trucks to areas facing groundwater depletion and drought. To address this challenge, UNICEF explored alternative, sustainable deeper groundwater sources that could be extracted using solar water pumping technology for multi water use. This paper describes a three-phase methodology of deep groundwater development of wells in the Ogaden Jesoma sandstone aquifers of the Somali region of the Horn of Africa to a depth of 600 meters below ground level. The results concluded that the deep sandstone aquifer of Jesoma can provide fresh water with yields of 15 l/s to the local population of Somali region. to the study provided insights into deep groundwater identification and development as well as adaptive deep boreholes drilling as a source for climate resilient water supplies.
ARTICLE | doi:10.20944/preprints201801.0276.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: dehydrins; 2D PAGE; drought; mitochondrial biogenesis; mitochondrial proteome; plant transcriptome
Online: 30 January 2018 (04:17:44 CET)
The early generative phase of cauliflower (Brassica oleracea var. botrytis) curd ripening is sensitive to the water deficit. Mitochondrial responses under drought within Brassica genus are poorly understood. The main goal of this study was to investigate the mitochondrial biogenesis of three cauliflower cultivars varying with drought tolerance. Diverse quantitative changes (down-regulations mostly) in the mitochondrial proteome were assayed by 2D PAGE coupled with LC-MS/MS. Respiratory (e.g. CII, CIV and ATP synthase subunits), transporter (including diverse porin isoforms) and matrix multifunctional proteins (e.g. components of RNA editing machinery) appeared diversely affected in their abundance under two drought levels. Western immunoassays showed also cultivar-specific responses of selected mitochondrial proteins. Dehydrin-related tryptic peptides found in few 2D spots that appeared immunopositive with dehydrin-specific antisera highlighted the relevance of mitochondrial dehydrin-like proteins for the drought response. The level of selected messengers participating in drought response was also determined. We conclude that the mitochondrial biogenesis was strongly, but diversely affected in various cauliflower cultivars and associated with drought tolerance on the proteomic and functional levels. However, transcriptomic and proteomic regulations were largely uncoordinated due to the suggested altered availability of messengers for translation, mRNA/ribosome interactions and/or miRNA impact on transcript abundance and translation.
ARTICLE | doi:10.20944/preprints202308.0181.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: rice (Oryza sativa L.); drought stress; Osdsm3; genetic analysis; fine mapping
Online: 2 August 2023 (07:58:40 CEST)
Drought poses a significant constraint on rice production, and in this study, we have discovered a novel drought-sensitive mutant, designated as dsm3, arising from the progenies of indica rice variety Zhonghui8015 treated with EMS. Under drought stress conditions, dsm3 exhibited characteristic withered leaf tips, accompanied by increased levels of MDA and H2O2, reduced Pn, and decreased activity of POD and SOD. Genetic analysis revealed that the withered leaf tip phenotype was governed by a single recessive gene, designated as Osdsm3.To begin with, Osdsm3 was initially mapped to the short arm of chromosome 1 through a cross involving dsm3 and 02428. Subsequently, utilizing a population of 2591 F2 individuals, we narrowed down the location of Osdsm3 to a 78Kb interval, encompassing 13 open reading frames (ORFs). Sequencing analysis unveiled a mutation (1275G→A) in the exon of the candidate gene (LOC_Os01g10680), leading to premature translation termination. Moreover, a quantitative RT-PCR assay demonstrated high expression of OsDSM3 in the panicle and sheath, with a significant upregulation of drought stress-related genes under drought conditions. Phylogenetic analyses indicated that Osdsm3 shares evolutionary homology with UNE1, an intracellular transport protein found in Arabidopsis thaliana. Subcellular studies further confirmed that OsDSM3 resides in the cytoplasm. In conclusion, the forthcoming cloning of Osdsm3 holds promise for delving deeper into the molecular mechanisms governing rice drought resistance.
ARTICLE | doi:10.20944/preprints202307.1046.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: ABA-related genes; drought stress; epigenetics; euchromatic histone modifications; Hordeum vulgare
Online: 17 July 2023 (04:07:59 CEST)
Plants respond to drought by major reprogramming of gene expression enabling the plant to survive this threatening environmental condition. One major upstream signal inducing this multifaceted process is the phytohormone abscisic acid (ABA). In this report, we investigate the drought response in barley plants (Hordeum vulgare, cv. Morex) at both epigenome and transcriptome levels. Leaves of barley plants after 10 days of drought treatment, when soil water content was decreased by about 40%, were compared to well-watered controls. Due to the drought treatment, chlorophyll content and photosystem II-efficiency were decreased by about 10% and some known drought-related genes were already induced. Global ChIPseq analyses were used to identify genes where histones 3 associated with promoter or gene body were modified with euchromatic K4 trimethylation or K9 acetylation during drought. Using stringent exclusion criteria, 129 genes loaded with H3K4me3 and 2008 genes loaded with H3K9ac in response to drought were identified, indicating that H3K9 acetylation reacts to drought more sensitive than H3K4 trimethylation. Comparison with differentially expressed genes enabled to identify those genes, which are loaded with the euchromatic marks and are induced in response to the drought treatment. The results show that a major part of these genes is involved in ABA-signaling and related pathways. Intriguingly, two members of the protein phosphatase 2C family (PP2Cs), which are involved in the central regulatory machinery of ABA signaling, were also identified by this approach.
ARTICLE | doi:10.20944/preprints202303.0229.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: rice; variety; selection; mutagenesis; gamma rays; fast neutrons; salinity; drought tolerance
Online: 13 March 2023 (10:28:52 CET)
The article presents research results of the γ-ray and fast neutrons impact on various rice species, in order to obtain mutant forms resistant to salinity (NaCl) and drought factors (sorbitol. They are going to be used as initial forms in synthetic selection when creating varieties, adapted to the stressful conditions of, both, soil and climate in the Kazakhstan Aral Sea. The average lethal doses (LD50) of γ-rays and fast neutrons, as well as the average NaCl and sorbitol lethal concentrations were established. Such environment is best suited for clear manifestation of the mutagenic effect of ionizing radiation and the resistance of rice plants to salinity and drought. A distinct dependence in the effect of ionizing radiation and stress factors on the number of induced resistant mutant forms has been related to the initial rice sort. The largest number of mutant forms was obtained from the local variety Syr Suluy, followed by Leader and AyKerim varieties. From all varieties, the number of mutants obtained from exposure to γ-rays was 43 pieces out of 4500 grains, and from the impact of fast neutrons - 115 pieces out of 2700 grains. M1 mutant plants significantly differ from the initial forms in terms of morphological features – plant height, panicle length, grain size Most plants are characterized by short growth and even dwarfism (˂80 cm). They are lodging tolerant, have short and highly sterile panicles, indicating that they are mutants and resistant to salinity, drought, or both.
ARTICLE | doi:10.20944/preprints202101.0357.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: GRACE; GRACE-FO; TWS; hydroclimatic; drought; flooding; Nile River Basin; Africa
Online: 18 January 2021 (15:14:32 CET)
This research assesses the changes in the total water storage (TWS) during the twentieth century and their future projections in the Nile River Basin (NRB) via TWSA (TWS anomalies) records from GRACE (Gravity Recovery and Climate Experiment), GRACE-FO (Follow-On), data-driven-reanalysis TWSA and land surface model (LSM), in association with precipitation, temperature records, and standard drought indicators. The analytical approach incorporates the development of 100+ yearlong TWSA records using a probabilistic conditional distribution fitting approach by the GAMLSS (Generalized Additive Model for Location, Scale, and Shape) model. The drought and flooding severity, duration, magnitude, frequencies, and recurrence were assessed during the studied period. The results showed, 1- The NRB between 2002 to 2020 has transited to substantial wetter conditions. 2- The TWSA reanalysis records between 1901 to 2002 revealed that the NRB had experienced a positive increase in TWS during the wet and dry seasons. 3- The projected TWSA between 2021 to 2050 indicated slight positive changes in TWSA during the rainy seasons. The analysis of drought and flooding frequencies between 1901 to 2050 indicated the NRB has ~64 dry-years compared to ~86 wet-years. The 100+ yearlong TWSA records assured that the NRB transited to wetter conditions relative to few dry spells. These TWSA trajectories call for further water resources planning in the region especially during flood seasons. This research contributes to the ongoing efforts to improve the TWSA assessment and its associated dynamics for transboundary river basins. It also demonstrates how an extended TWSA record provides unique insights for water resources management in the NRB and similar regions.
REVIEW | doi:10.20944/preprints202101.0213.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: crop diversification; C3 xerophtyes; food security; underutilized crops; drought adaptation strategies
Online: 12 January 2021 (10:19:08 CET)
Citron watermelon (Citrullus lanatus var. citroides) is an underexploited and under-researched crop species with potential to contribute to crop diversification in sub-Saharan Africa and beyond. The species is commonly cultivated in the drier parts of Southern Africa, mainly by smallholder farmers who maintain a wide range of landraces. Understanding the molecular and morpho-physiological basis for drought adaptation of Citron watermelon in these dry environments can aid in screening local germplasm, identification of suitable traits for crop improvement and improving food system resilience among smallholder farmers by adding to crop diversification. This paper reviews literature on drought adaptation of C. lanatus spp. (C3 xerophytes), using the systematic review approach. The review discusses; (i) the potential role of citron watermelon in adding to crop diversification, (ii) alternative food uses and potential by-products that can be processed from citron watermelon and (iii) the role of Sub-Saharan farmers as key actors in conserving citron watermelon germplasm and biodiversity. Finally, the review provides a summary of significant findings and identifies critical knowledge gaps for further research.
ARTICLE | doi:10.20944/preprints202012.0362.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: combined stresses; drought stress; heat stress; maize; root morphology; root types
Online: 15 December 2020 (09:39:56 CET)
Plants are continually exposed to multiple stresses, which co-occur in nature and the net effects are frequently more non-additive (i.e., synergistic or antagonistic) suggesting ‘unique’ responses respect to that of the individual stress. Further, plant stress responses are not uniforms showing a high spatial and temporal variability among and along the different organs. In this respect, the present work investigated the morphological responses of different root types (seminal, seminal lateral, primary, primary lateral) of maize plants exposed to single (drought and heat) and combined stress (drought + heat). Data were evaluated by a specific root image analysis system (WinRHIZO) and analyzed by uni- and multi-variate statistical analysis. The results indicated that primary root and their laterals were the types more sensitive to the single and combined stresses while the seminal laterals specifically responded to the combined only. Further, antagonistic and synergistic effects were observed for the specific traits in the primary and their laterals and in the seminal lateral roots in response to the combined stress. These results suggested that maize root system modified specific root types and traits to face with different stressful environmental conditions highlighting that the adaptation strategy to the combined stress may be different from that of the individual ones. The knowledge of “unique or shared” responses of plant to multiple stress can be utilized to develop varieties with broad spectrum stress tolerance.
ARTICLE | doi:10.20944/preprints202009.0673.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: forest monitoring; drought; time series satellite data; Bowen ratio; carbon flux
Online: 27 September 2020 (10:25:33 CEST)
Monitoring drought impacts in forest ecosystems is a complex process, because forest ecosystems are composed of different species with heterogeneous structural compositions. Even though forest drought status is a key control on the carbon cycle, very few indices exist to monitor and predict forest drought stress. The Forest Drought Indicator (ForDRI) is a new monitoring tool developed by the National Drought Mitigation Center (NDMC) to identify forest drought stress. ForDRI integrates 12 types of data, including satellite, climate, evaporative demand, ground water, and soil moisture, into a single hybrid index to estimate tree stress. The model uses Principal Component Analysis (PCA) to determine the contribution of each input variable based on its covariance in the historical records (2003–2017). A 15-year time series of 780 ForDRI maps at a weekly interval were produced. The ForDRI values at a 12.5km spatial resolution were compared with normalized weekly Bowen ratio data, a biophysically based indicator of stress, from nine AmeriFlux sites. There were strong and significant correlations between Bowen ratio data and ForDRI at sites that had experienced intense drought. In addition, tree ring annual increment data at eight sites in four eastern U.S. national parks were compared with ForDRI values at the corresponding sites. The correlation between ForDRI and tree ring increments at the selected eight sites during the summer season ranged between 0.46 and 0.75. Generally, the correlation between the ForDRI and normalized Bowen ratio or tree ring increment are reasonably good and indicate the usefulness of the ForDRI model for estimating drought stress and providing decision support on forest drought management.
REVIEW | doi:10.20944/preprints202008.0359.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Abiotic stress; Melatonin; Water stress; Drought; Waterlogging; Antioxidants; Stress signalling, phytohormones
Online: 17 August 2020 (10:19:52 CEST)
Water stress (drought and waterlogging) is drastic abiotic stress to plant growth and development. Melatonin, bioactive plant hormone, has been widely tested in drought situations in diverse plant species, while a few studies on the role of melatonin in waterlogging stress conditions have been published. In the current review, we analyze the bio-stimulatory functions of melatonin on plants under both drought and waterlogging stress. Melatonin controls the levels of reactive oxygen and nitrogen species and positively changes the molecular defense to improve plant tolerance against drought and waterlogging stress. Moreover, the crosstalk of melatonin and other phytohormones is a key element on plant survival under drought stress, while this relationship needs further investigation under waterlogging stress. In this review, we draw the complete story of water stress on both sides: drought and waterlogging through discussing the previous critical studies under both conditions. Moreover, we suggest several research directions, especially for waterlogging, which remains a big vague piece of melatonin and water stress puzzle.
Subject: Biology And Life Sciences, Plant Sciences Keywords: drought stress; osmotic stress; rice; transcription factors; stress signaling; qtl; breeding
Online: 24 December 2019 (11:39:50 CET)
Many studies were done in the development of drought stress-tolerant transgenic plants, including crop plants. Rice is considered to be a vital crop target for improving drought stress tolerance. Much transgenic rice showed improved drought stress tolerance was reported to date. They are genetically engineered plants that are developed by using genes that encode proteins involved in drought stress regulatory networks. These proteins include protein kinases, transcription factors, enzymes related to osmoprotectant or plant hormone synthesis, receptor-like kinase. Of the drought stress-tolerant transgenic rice plants described in this review, most of them display retarded plant growth. In crop crops, plant health is a fundamental agronomic trait that can directly affect yield. By understanding the regulatory mechanisms of retarded plant growth under drought stress, conditions are necessary precursors to developing genetically modified plants that result in high yields.
ARTICLE | doi:10.20944/preprints201907.0083.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: unmanned aerial vehicles; vegetation water status; drought; NDVI; NDRE; Baccharis pilularis
Online: 4 July 2019 (17:42:29 CEST)
Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study, we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush), at the Blue Oak Ranch Reserve (BORR) near San Jose, California. We recorded multispectral data from the plants at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI and NDRE, and plant water content and water potential, as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit in plants and distinguish them from control and watered plants; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of plant water content than NDRE. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope) and found that PlanetScope data was able to capture the overall trend in treatments but was not able to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.
ARTICLE | doi:10.20944/preprints202307.1202.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Amorpha fruticose, WRKY transcription factor, drought stress, tobacco genetic transformation, stress resistance
Online: 18 July 2023 (11:06:04 CEST)
The WRKY gene family in plants regulates the plant's response to drought through regulatory networks and hormone signaling. AfWRKY20 (MT859405) was cloned from A. fruticosa (Amorpha fruticosa,A. fruticosa) seedlings using RT-PCR. The binding properties of the AfWRKY20 protein and the W-box (a DNA cis-acting element) were verified both in vivo and in vitro using EMSA and Dual-Luciferase activity assays. RT-qPCR detected that the total expression level of AfWRKY20 in leaves and roots was 22 times higher in the 30% PEG6000 simulated drought treatment compared to the untreated group. Under the simulated drought stress treatments of sorbitol and ABA (abscisic acid,ABA), the transgenic tobacco with the AfWRKY20 gene showed enhanced drought resistance at the germination stage, with significantly increased germination rate, green leaf rate, fresh weight, and root length compared to the WT (wild type,WT) tobacco. In addition, the SOD (superoxide dismutase,SOD)activity, chlorophyll content, and Fv/Fm ratio of AfWRKY20 transgenic tobacco were significantly higher than those of the WT tobacco under natural drought stress, while the MDA (malondialdehyde,MDA) content and DAB (3,3'-diaminobenzidine,DAB) and NBT (nitroblue tetrazolium,NBT) staining levels were lower. The expression levels of oxidation kinase genes (NbSOD, NbPOD, and NbCAT) in transgenic tobacco under drought stress were significantly higher than those in WT tobacco. This enhancement in gene expression improved the ability of transgenic tobacco to detoxify ROS (reactive oxygen species,ROS). The survival rate of transgenic tobacco after natural drought rehydration was four times higher than that of WT tobacco. In summary, this study revealed the regulatory mechanism of AfWRKY20 in response to drought stress-induced ABA signaling, particularly in relation to the ROS. This finding provides a theoretical basis for understanding the pathways of WRKY20 involved in drought stress, and offers genetic resources for molecular plant breeding aimed at enhancing drought resistance.
ARTICLE | doi:10.20944/preprints202306.2191.v1
Subject: Environmental And Earth Sciences, Geography Keywords: groundwater; hydro-meteorological conditions; Łeba Barrier; Southern Baltic coast; monitoring, drought; hazard
Online: 30 June 2023 (09:01:09 CEST)
The Baltic Sea coast is one of the geographical areas of Europe most threatened by the current climate change. This issue concerns erosional processes, groundwater flows affecting sea-shore settings. Long term hydrological investigations within the western sector of the Łeba Barrier, northern Poland, based on a network of monitoring stations, coupled with the meteorology records of the past 12 years, revealed significant fluctuations in ground water fluxes from the Baltic Sea on the adjoining mainland. Groundwater resources are negatively affected by sea-level drops in the coastal areas along the southern Baltic coast. The low sea levels strengthen the effects of low precipitation and high temperatures, causing altogether the occurrence of hydrogeological drought in the coastal sandbar areas. Drought periods are characterized by lowering of water-tables in the Slowinski National Park. The obtained results have direct relevance to a long-term assessment of water resources, environmental protection of the climatically most susceptible ecosystems, as well as the tourism management of this popular visitors’ destination.
ARTICLE | doi:10.20944/preprints202306.1510.v1
Subject: Biology And Life Sciences, Forestry Keywords: Betula pendula; Betula pubescens; drought; growth decline; land use; peatland; Toledo Mountains
Online: 21 June 2023 (09:50:13 CEST)
South rear-edge populations of widely distributed temperate and boreal tree species such as birches (Betula pubescens and B. pendula) are considered particularly vulnerable to climate warming, and at the same time they constitute genetic reservoirs of drought-adapted ecotypes. Here, we compared radial growth patterns and responses to climate, river or dam flows and a drought index of rear-edge (southernmost) populations (Toledo Mountains, central-southern Spain) with populations located in northern Spain of B. pubescens and B. pendula. Then, we per-formed a comparative analysis across Europe of B. pendula populations. The main climatic con-straint of birch growth was high summer water deficit, although the effect of local hydrological conditions was particularly important in rear-edge populations. We found declining growth trends in rear-edge stands since the early 21st century, related to decreasing water availability and increasing aridity. Our results also suggested distinct growth patterns and climate-growth associations of B. pendula across Europe that show how populations further south and in warmer locations were more sensitive to the drought. In conclusion, drought-induced growth decline can be exacerbated by local human land uses leading to reduced river inflow, thus endangering birch populations at their southern distribution limit. Protection of endangered rear-edge birch populations requires adequate management of local water resources.
ARTICLE | doi:10.20944/preprints202304.0590.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: rice; variety; selection; mutagenesis; gamma rays; fast neutrons; salinity; drought tolerance; LD50
Online: 19 April 2023 (10:53:56 CEST)
The article presents the results of the γ-ray and fast neutrons impact on various rice species, in order to obtain mutant forms resistant to salinity (NaCl) and drought factors (sorbite). They are going to be used as initial forms in synthetic selection when creating varieties, adapted to the stressful conditions of, both, soil and climate in the Kazakhstan Aral Sea. The average lethal doses (LD50) of γ-rays and fast neutrons, as well as, the average NaCl and sorbite lethal concentrations were established. A distinct dependence on the effect of ionizing radiation and stress factors on the number of induced resistant mutant forms has been related to the initial rice variety. The largest number of mutant forms was obtained from the local variety Syr Suluy, followed by Leader and Aikerim varieties. Out of all varieties, only 1% of the initially irradiated by γ-rays seeds survived, while after fast neutron irradiation – 4,3%. M1 mutant plants significantly differ from the initial forms in terms of morphological features – plant height, panicle length, and grain size. They are tolerant to lodging, and have short and highly sterile panicles, indicating that they are mutants.
ARTICLE | doi:10.20944/preprints202101.0164.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Arbutus unedo L. Artificial Pollination, Breeding, Drought stress, Microscopy, Pollen, Physiological performance
Online: 8 January 2021 (14:08:49 CET)
Arbutus unedo L. is a small Ericaceae tree with a circum-Mediterranean distribution. It has a huge ecological impact on southern Europe forests and a great economic importance, as a source of phytochemicals with bioactive properties and for fruit production. On the foreseen climate change context, breeding towards drought tolerance is necessary in order to ameliorate plant performance. The aim of this work was therefore to study the reproduction mechanisms of strawberry tree, obtain new genetic combinations by hybridization and select genotypes more tolerant to drought stress. A morphological analysis of flowers and pollen was carried out, and controlled pollinations performed both in vitro and ex vitro. The very first approach on strawberry tree breeding by means of hybridization is also presented. Several physiological parameters were evaluated on 26 genotypes submitted to a water deficit regime. Plant behavior under drought greatly varied among genotypes, which showed a high phenotype plasticity. Three genotypes that were able to cope with water restriction without compromising net CO2 assimilation were identified as highly tolerant to drought stress. The results obtained elucidate the reproduction mechanisms of strawberry tree and open the way for a long-term breeding program based on the selection of drought tolerant plants.
ARTICLE | doi:10.20944/preprints202011.0550.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Basmati rice; QTL introgression; near isogenic lines; yield under drought; climate resilience
Online: 20 November 2020 (20:45:02 CET)
Drought stress at the reproductive stage in rice is one of the most important cause for yield reduction, affecting both productivity and quality. All Basmati rice varieties, including the popular cultivar ‘Pusa Basmati 1 (PB1)’ is highly sensitive to reproductive stage drought stress (RSDS). We report for the first time, improvement of a Basmati cultivar for RSDS tolerance, with the introgression of a major quantitative trait locus (QTL), ‘qDTY1.1’ into PB1. The QTL donor was sourced from an aus variety, Nagina 22 (N22). A QTL linked microsatellite (SSR) marker ‘RM 431’ was employed for foreground selection for qDTY1.1 in the marker assisted backcross breeding process. A set of 113 SSR markers polymorphic between N22 and PB1 were utilized for background selection to ensure higher genome recovery. After three backcrosses followed by five generations of selfing, eighteen near isogenic lines (NILs) were developed, through combinatory selection for agro-morphological, grain and cooking superiority traits. The NILs were evaluated for three consecutive Kharif seasons, 2017, 2018 and 2019 under well-watered and drought stress conditions. RSDS tolerance and yield stability indicated that NIL3, NIL5, NIL6, NIL7, NIL12, NIL15 and NIL17 were best in terms of overall agronomic and grain quality under RSDS. Additionally, NILs exhibited high yield potential under normal condition as well. The RSDS tolerant Basmati NILs with high resilience to water stress, is a valuable resource for sustaining Basmati rice production under water limiting production environments.
ARTICLE | doi:10.20944/preprints202008.0684.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Chlorophyll Fluorescence; SIF; Drought; Spectral Vegetation Indices; GOME-2; Abiotic Stress; Caatinga
Online: 30 August 2020 (18:24:28 CEST)
Sun-Induced chlorophyll Fluorescence (SIF) relates directly to photosynthesis yield and stress but there are still uncertainties in its interpretation. Most of these uncertainties concern the influences of the emitting vegetation’s structure (e.g., leaf angles, leaf clumping) and biochemistry (e.g., chlorophyll content, other pigments) on the radiative transfer of fluorescent photons. The Caatinga is a large region at northeast Brazil of semiarid climate and heterogeneous vegetation, where such biochemical and structural characteristics can vary greatly even within a single hectare. With this study we aimed to characterize eleven years of SIF seasonal variation from Caatinga vegetation (2007 to 2017) and to study its responses to a major drought in 2012. Orbital SIF data from the instrument GOME-2 was used along with MODIS MAIAC EVI and NDVI. Environmental data included precipitation rate (TRMM), surface temperature (MODIS) and soil moisture (ESA CCI). To support the interpretation of SIF responses we have used red and far-red SIF adjusted by the Sun’s zenith angle (SIF-SZA) and by daily Photosynthetically Active Radiation (dSIF). Furthermore, we have also adjusted SIF through two contrasting formulations using NDVI data as proxy for structure and biochemistry, based on previous leaf-level and landscape level studies: SIF-Yield and SIF-Prod. Data was tested with time-series decomposition, rank correlation, spatial correlation and Linear Mixed Models (LMM). Results show that GOME-2 SIF and adjusted SIF formulations responded consistently to the observed environmental variation and showed a marked decrease in SIF emissions in response to a 2012 drought, that was generally larger than the corresponding NDVI and EVI decreases. Drought sensitivity of SIF, as inferred from LMM slopes, was correlated to land cover at different regions of the Caatinga. This is the first study to show correlation between landscape-level SIF and an emergent property of ecosystems (i.e., resilience), showcasing the value of remotely sensed fluorescence for ecological studies.
ARTICLE | doi:10.20944/preprints202004.0164.v2
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: drought; climate variability; resilience; resistance; estuary; fish; extreme events; Delta Smelt; Chinook Salmon; Largemouth Bass
Online: 23 July 2020 (10:30:03 CEST)
Many estuarine ecosystems and the fish communities that inhabit them have undergone substantial changes in the past several decades, largely due to multiple interacting stressors that are often of anthropogenic origin. Few are more impactful than droughts, which are predicted to increase in both frequency and severity with climate change. In this study, we examined over five decades of fish monitoring data from the San Francisco Estuary, California, U.S.A, to evaluate the resistance and resilience of fish communities to disturbance from prolonged drought events. High resistance was defined by the lack of decline in species occurrence from a wet to a subsequent drought period, while high resilience was defined by the increase in species occurrence from a drought to a subsequent wet period. We found some unifying themes connecting the multiple drought events over the fifty-year period. Pelagic fishes consistently declined during droughts (low resistance), but exhibit a considerable amount of resiliency and often rebound in the subsequent wet years. However, full recovery does not occur in all wet years following droughts, leading to permanently lower baseline numbers for some pelagic fishes over time. In contrast, littoral fishes seem to be more resistant to drought and may even increase in occurrence during dry years. Based on the consistent detrimental effects of drought on pelagic fishes within the San Francisco Estuary and the inability of these fish populations to recover in some years, we conclude that freshwater flow remains a crucial but not sufficient management tool for the conservation of estuarine biodiversity.
ARTICLE | doi:10.20944/preprints201812.0139.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: drought; water management; thermal remote sensing; habitats protection; land surface temperature; CWSI
Online: 12 December 2018 (05:27:14 CET)
The research carried out concerned the laboratory assessment of the applicability of the Crop Water Stress Index (CWSI) as a practical tool for assessing the risk of desiccation for selected wetland habitats: transition mires and quaking bogs as well as alkaline fens. The analysis was carried out on 3 soil samples with a vegetation cover (with the dimensions of 40×40×30 cm) collected during the full vegetation season for each mentioned habitat, with a characteristic species composition. Experimental research was carried out between 17th May 2018 and 19th June 2018. Thermal, RGB and multispectral images, chlorophyll content, volumetric soil moisture, air temperature and relative humidity measurements were taken for each sample every two days. The obtained results clearly indicate the dependence between CWSI and plant condition parameters in the first phase of desiccation. At the same time, as a result of the observations taken, thresholds have been set, indicating different desiccation phases.
ARTICLE | doi:10.20944/preprints201811.0282.v1
Subject: Biology And Life Sciences, Forestry Keywords: adaptive forestry; dendroecology; diffuse–porous wood; drought years; vessel traits; wood anatomy
Online: 12 November 2018 (10:31:23 CET)
The distribution of Mexican Magnolia species´ occur under restricted climatic conditions. As many other tree species from the tropical montane cloud forests (TMCF), Magnolia species appear to be sensitive to drought. Through the use of dendrochronological techniques, this study aims to determine the climate influence on the vessel traits of M. vovidesii and M. schiedeana which are endangered tree species that are endemic to the Sierra Madre Oriental in eastern Mexico. Because most of the tree species in TMCFs are sensitive to climate fluctuations, it is necessary to investigate the differences in the climatic adaptability of the vessel architecture of these trees. This could allow us to further understand the potential peril of climate change on TMCFs. We compared vessel frequency, length and diameter in drought and non–drought years in two Mexican Magnolia species. We used tree–rings width and vessel traits to assess the drought effects on Magnolias’ diffuse–porous wood back to the year 1929. We obtained independent chronologies for M. vovidesii with a span of 75 years (1941–2016), while for M. schiedeana we obtained a span of 319 years (1697–2016). We found that temperature and precipitation are strongly associated with differences in tree–ring width (TRW) between drought and non–drought years. Our results showed anatomical differences in vessel trait response between these two Magnolia species to climatic variation. We suggest that our approach of combining dendroclimatic and anatomical techniques is a powerful tool to analyse anatomic wood plasticity to climatic variation in Magnolia species.
ARTICLE | doi:10.20944/preprints201810.0518.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Korean fir; hierarchical regression model; climate change; seedling survival; dwarf bamboo; drought
Online: 23 October 2018 (05:00:38 CEST)
Regional declines of the Korean fir (Abies koreana) have been observed since the 1980s on the subalpine region. To explain this decline, it is fundamental to investigate the degree to which environmental factors have contributed to plant distributions on diverse spatial scales. We applied a hierarchical regression model to determine quantitatively the relationship between the abundance of Korean fir (seedlings) and diverse environmental factors across two different ecological scales. We measured Korean fir density and the occurrence of its seedlings in 102 (84) plots nested at five sites and collected a range of environmental factors at the same plots. Our model included hierarchical explanatory variables at both site-level (weather conditions) and plot-level (micro-topographic factors, soil properties, and competing species). The occurrence of Korean fir seedlings was positively associated with moss cover and rock cover but negatively related to dwarf bamboo cover. On site-level, winter precipitation was significantly positively related to the occurrence of seedlings. A hierarchical Poisson regression model revealed that Korean fir density were negatively associated with slope aspect, topographic position index, Quercus mongolica cover, and mean summer temperature. Our results suggest that drought and competition with other species are factors which halt the survival of Korean fir. We can predict that the population of Korean fir will continue to decline on the Korean Peninsula due to rising temperatures and seasonal drought, and only a few Korean fir will survive on northern slopes or valleys where competition with dwarf bamboo and Q. mongolica can be avoided.
ARTICLE | doi:10.20944/preprints201806.0426.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: rice, abiotic stress, high temperature, drought, physiological responses, molecular mechanisms, systems biology
Online: 26 June 2018 (15:30:20 CEST)
Rice production, owing to its high-water requirement for cultivation, is very vulnerable to the threat of changing climate, particularly prolonged drought and high temperature. Such threats heighten the need for abiotic stress-resilient rice varieties with better yield potential. This review examines the physiological and molecular mechanisms of rice varieties to cope with stress conditions of drought (DS), high temperature (HTS) and their combination (DS-HTS). It appraises research studies in rice about its various phenotypic traits, genetic loci and response mechanisms to stress conditions to help craft new breeding strategies for rice varieties with improved resilience to abiotic stresses. This review consolidates available information on promising rice cultivars with desirable traits as well as advocates synergistic and complementary approaches in molecular and systems biology to develop new rice breeds that favorably respond to climate-induced abiotic stresses. The development of new breeding and cultivation strategies for climate-resilient rice varieties is a challenging task. It requires a comprehensive understanding of the various morphological, biochemical, physiological, and molecular components governing yield under drought and high temperature, but possible by implementing cohesive approaches involving molecular and systems biology approaches in genomics and molecular breeding, including genetic engineering.