Subject: Biology, Agricultural Sciences & Agronomy Keywords: Fitotoxicity; Seedling development; Germination; Micronuclei; Citotoxicity; Genotoxicity.
Online: 23 September 2022 (02:09:04 CEST)
Brazil is the number-one country in pesticide consumption, and corn is the second most cultivated crop in the country. Chemical control of weeds associated with corn cultivation is performed by application of herbicides with pre- and postemergence action, such as S-metolachlor. Currently, the toxicity of herbicides is a task of great concern. In this regard, the present study aimed to evaluate the effects of an S-metolachlor-based herbicide through bioassays with the plant model Lactuca sativa L. (lettuce) and Zea mays L. (maize). The herbicidal test solutions containing 7.5, 15, 30, 60, 120, 240, 360, 480, 600, and 720 mg L-1 of the active ingredient S-metolachlor were prepared from commercial products. Distilled water was used as a negative control, and aluminum was used as a positive control. Macroscopic analyses (germination and growth) were performed for the two species, and microscopic analyses (chromosomal and nuclear changes) were performed for L. sativa. Negative interference of the S-metolachlor-based herbicide on lettuce was observed for all macroscopic and microscopic parameters tested. In maize, there was no significant interference in germination; however, the herbicide interferes negatively in seedling development. In brief, the herbicide based on S-metolachlor has phytotoxic potential, just as discussed.
ARTICLE | doi:10.20944/preprints202003.0441.v1
Online: 31 March 2020 (04:21:07 CEST)
Hymenaea courbaril is an endangered species, promising to reforestation programs and mainly explored as a wood source. The available information concerning long-term storage methods, seed recalcitrance, parental, and substrate influence is scarce. This study focused on the seed behavior according to population origin and during one-year storage, also testing the efficiency of the low-temperature conservation. Variations between the uncertainty indexes were found to the studied populations after long-term storage. There was no significant loss of the germination potential in consequence of the prolonged storage period. Although, older seeds promoted gradually greater delayed germination. Germination speed, synchrony, and uncertainty indexes were substantially different between the -20° conservation and control. H. courbaril seeds are capable of long-term storage without losing their germination potential, indicating an orthodox behavior.
ARTICLE | doi:10.20944/preprints202203.0351.v1
Subject: Engineering, Automotive Engineering Keywords: vegetable; seedling quality; automatic transplanting; substrate improvement; consolidation strength
Online: 25 March 2022 (15:52:36 CET)
Automation of vegetable seedling transplanting has provided opportunities for saving labors and improving productivity. Some changes in seedling agronomy are necessary for efficient transplanting. In this study, the local nursery substrates were added with the herbaceous peat, the sphagnum peat and the coir peat, respectively. Effects of the new compound substrates were investigated on the seedling qualities and the root-substrate strength. In the results, we found that the addition of these horticultural mediums significantly affected the physiochemical properties of the original substrates. Under the same nursery conditions, some appropriate additions could promote the seedling growth. And the deficient or excessive additions were to inhibit the growing development of seedlings and their roots. The corresponding additions would also improve the structural characteristics of the root lumps. Generally, the nursery substrates added with the sphagnum peat were relatively optimized in contribution to the seedling qualities and the root-substrate strength. Especially as the commercial substrate and the sphagnum peat were mixed at the volume ratio of 2:1, the dry matter accumulation of seedlings was 2.18 times more than the original. Their root lumps had the best consolidation strength, which may be an effective application for the necessary qualities of seedlings for automatic transplanting.
REVIEW | doi:10.20944/preprints202001.0243.v1
Subject: Biology, Plant Sciences Keywords: DOF proteins; DELLA proteins; seed germination; seedling development; seed maturation
Online: 21 January 2020 (11:16:52 CET)
The DOF (DNA binding with one finger) family of plant-specific transcription factors (TF) was first identified in maize in 1995. Since then, DOF proteins have been shown to be present in the whole plant kingdom including the unicellular alga Chlamydomonas reinhardtii. The DOF TF family is characterised by a highly conserved DNA binding domain (DOF domain), consisting of a CX2C-X21-CX2C motif which is able to form a zinc finger structure. Early in the study of DOF proteins it became clear their relevance for seed biology. Indeed, the Prolamine Binding Factor (PBF), one of the first DOF proteins characterised, controls the endosperm-specific expression of the zein genes in maize. Subsequently, several DOF proteins from both monocots and dicots have been shown to be primarily involved in seed development, dormancy and germination, as well as in seedling development and other light-mediated processes. In the last two decades the molecular network underlying these processes have been outlined, and the main molecular players and their interactions have been identified. In this review, we will focus on the DOF TFs involved in these molecular networs, and on their interaction with other proteins.
ARTICLE | doi:10.20944/preprints202102.0122.v2
Subject: Biology, Anatomy & Morphology Keywords: tomato; temperature; damage; seedling; plant; root; weight; photosynthesis; proline; electrical conductivity
Online: 20 May 2021 (09:45:18 CEST)
High temperature (HT) significantly affects the crop physiological traits and reduces the 12 productivity in plants. To increase yields as well as survival of crops under HT, developing heat13 tolerant plants is one of the main targets in crop breeding programs. The present study attempted 14 to investigate the linkage of the heat tolerance between the seedling and the reproductive growth 15 stages of tomato cultivars ’Dafnis‘ and ’Minichal’. This research was undertaken to evaluate heat 16 tolerance under two experimental designs such as screening at seedling stage and screening from 17 reproductive traits in greenhouses. Survival rate and physiological responses in seedlings of 18 tomatoes with 4-5 true leaf were estimated under HT (40 °C, RH 70%, day/night, respectively) and 19 under two control and HT greenhouse conditions (day time 28 °C and 40 °C, respectively). Heat 20 stress significantly affected physiological-chemical (photosynthesis, electrolyte conductivity, 21 proline) and vegetative parameters (plant height, shoot fresh weight, root fresh weight) in all 22 tomatoes seedlings. The finding revealed that regardless of tomato cultivars the photosynthesis, 23 chlorophyll, total proline and electrical conductivity parameters were varied in seedlings during the 24 heat stress period. The heat tolerance rate of tomatoes in the seedling stage might not be associated 25 always with reproductive parameters. HT reduced the fruit parameters likeas fruit weight (31.9%), 26 fruit length (14.1%), fruit diameter (19.1%) and fruit hardness (9.1%) in compared to NT under HT 27 in heat susceptible tomato cultivar ‘Dafnis’, while in heat tolerant cultivar ‘Minichal’ fruit length 28 (7.1%) and fruit diameter (12.1%) was decreased by the affect of HT but on the contrary fruit weight 29 (3.6%) and fruit hardness (8.3%) were increased. In conclusion, screening and selection for tomatoes 30 should be evaluated at the vegetative and reproductive stages with consideration of reproductive 31 parameters.
ARTICLE | doi:10.3390/sci1010032
Subject: Keywords: germination; heteromorphism; imbibition; seed color; seedling growth; sodium chloride; <i>Trifolium pratense</i>
Online: 21 June 2019 (00:00:00 CEST)
The seeds of red clover are heteromorphic and two color morphs can be visually recognized, light purple and yellow, resulting from heterozygosity and recessive homozygosity at two loci. Here, we report the responses of seed imbibition, seed germination, and early seedling growth of the two morphs to distilled water, sodium chloride, and complete nutrient solution. The sensitivity of red clover seeds to treatments increased with the stage of development in what seems to be a cumulative process. No differences were found in seed imbibition between morphs or between treatments. In seedling growth, on the contrary, treatments were always effective, but differences between morphs were only observed in seeds that were treated with nutrient solution, whereas in the intermediate stage of seed germination, the effects by treatments were observed together with the appearance of differences between morphs in distilled water and in the treatment by sodium chloride solution. Simultaneously, the superior performance of the yellow morph that was found in germination, which appears to be a trait stable across cultivars of red clover seeds, turned into a superior performance of the light purple morph in seedling growth.
ARTICLE | doi:10.20944/preprints201810.0518.v1
Subject: Earth Sciences, Environmental Sciences 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/preprints201808.0493.v1
Subject: Life Sciences, Genetics Keywords: Weed competitive ability; early seed germination and seedling vigor traits; quantitative trait loci (QTLs); single nucleotide polymorphism; direct seeded rice
Online: 29 August 2018 (10:46:02 CEST)
Weed competitive ability (WCA) is a desirable key trait for the improvement of grain yield under direct-seeded rice (DSR) and the aerobic rice ecosystem. The present study targeted screening of 167 introgression lines (ILs) of a Green Super Rice (GSR) IR2-6 population derived from a cross between Weed Tolerant Rice 1 (WTR1) as the recipient parent and Y134 as the donor parent developed at IRRI for weed competitiveness in screen house conditions (SHC). The ILs were phenotyped for WCA traits such as early seed germination (ESG) and early seedling vigor (ESV) in Petri dishes and pot experiment conditions. The results of phenotypic variance revealed ESG-related traits, especially first germination count (1st GC) that positively correlated with second germination count (2nd GC), germination percentage (GP), total dry weight (TDW), total fresh weight (TFW), and vigor index (VI-1), whereas, in ESV, all the traits were positively correlated with each other except for three traits: root dry weight (RDW), 1st GC, and GP-2. The ESG and ESV traits are vital for weed competitiveness. A 6K SNP array was used to study the genetic association for the WCA traits. Forty-four QTLs for WCA traits were mapped on all chromosomes (except on chromosomes 4 and 8) through single marker analysis (SMA). Out of 44 QTLs, 29 were associated with ESG traits and 15 with ESV traits, with LOD scores of 2.93 to 8.03 and 2.93 to 5.04 and explained phenotypic variance ranging from 7.85% to 19.9% and from 7.85% to 13.2%, respectively. However, 31 QTLs were contributed by a negative additive allele from Y134, whereas a positive additive allele was contributed by WTR1 in 13 QTLs. Among them, two QTL hotspot regions were mapped on chromosome 11 (24.7-27.9 Mb) and chromosome 12 (14.8-17.4 Mb). The majority of the QTLs related to WCA traits were grouped into two QTL hotspots: QTL hotspot-I (qAFW11.1, qFC11.1, qFC11.2, qSC11.1, qGP-111.1, qGP-111.2, qTFGS11.1, qVI-111.1, and qVI-111.2) and QTL hotspot-II (qFC12.1, qFC12.2, qSC12.1, qFC12.2, qGP-112.1, qGP-112.2, qTFGS12.1, qTFGS12.2, qVI-112.1, qIV12.2, qFC12.1, and qGC12.2), and a few of them were co-localized on chromosomes 11 and 12. Further, we fine-tuned in the genomic regions of QTL hotspots and identified a total of 13 putative candidate genes on chromosomes 11 and 12 collectively. The present study is the first report on the genetic basis of WCA-related traits and the co-localized QTLs, which could be highly valuable in future breeding programs aiming to improve WCA in rice.
REVIEW | doi:10.20944/preprints201807.0432.v1
Subject: Biology, Plant Sciences Keywords: Seed coat; pericarps; floral bracts; glumes; dead organs enclosing embryos; seed germination; seedling establishment; hydrolytic enzymes; ROS detoxifying enzymes; cell wall modification enzymes; nutrients; phytohormones; nucleases; chitinases; Brassicaceae; Poaceae
Online: 26 July 2018 (09:53:41 CEST)
Plants have evolved a variety of dispersal units whereby the embryo is enclosed by various dead protective layers derived from maternal organs of the reproductive system including seed coats (integuments), pericarps (ovary wall, e.g., indehiscent dry fruits) as well as floral bracts (e.g. glumes) in grasses. Commonly, dead organs enclosing embryos (DOEEs) are assumed to provide a physical shield for embryo protection and means for dispersal in the ecosystem. In this review article, we will highlight recent studies showing that DOEEs of various species across families also have the capability for long-term storage of various substances including active proteins (hydrolases, ROS detoxifying enzymes), nutrients and metabolites that have the potential to support the embryo during storage in the soil and assist in germination and seedling establishment. We discuss a possible role for DOEEs as natural coatings capable of ‘engineering’ the seed microenvironment for the benefit of the embryo, the seedling and the growing plant.