Biology and Life Sciences

Abstract: Selenium (Se) is an essential micronutrient whose dietary supply varies widely because Se concentrations in plant foods depend on geography, substrate chemistry, crop species, and production practices. Agronomic biofortification can raise Se concentrations in edible tissues, but open-field outcomes are often inconsistent because fertilizer fate and plant uptake are governed by soil properties and weather. Controlled-environment agriculture (CEA) allows Se form, concentration, exposure duration, nutrient interactions, and aerial conditions to be regulated more precisely. This review examines the physiological basis of Se uptake and assimilation, the suitability of CEA platforms for Se delivery, the influence of nutrient-solution and environmental factors, effects on yield and phytochemical quality, food-safety considerations, and priorities for commercial deployment. In hydroponic studies, selenate supplied at roughly 2–16 µM typically raised leaf Se by one to two orders of magnitude with little or no yield penalty, whereas higher concentrations reduced biomass in some cultivars. Responses differ among species, cultivars, Se forms, and experimental systems, so universal application rates cannot yet be recommended. We propose that CEA biofortification be designed around a serving-based target window, and that future work prioritize harmonized fresh- and dry-weight reporting, Se speciation, solution mass balance, batch variability, economic evaluation, and commercial-scale validation.

Abstract: Bougainvillea is among the most economically and horticulturally important flowering shrubs worldwide, yet its genetic improvement is severely constrained by low natural seed-set and frequent embryo abortion. Existing micropropagation protocols rely predominantly on nodal stem segments and thus bypass a totipotent callus phase, limiting their utility for molecular breeding and genetic manipulation. In this study, we systematically evaluated and compared the in vitro morphogenic competence of -young leaf versus seed-derived juvenile hypocotyl explants in B. glabra Choisy 'Light Violet'. Although -young leaf explants readily formed vigorous calli on medium containing 2.0 mg/L 6-benzylaminopurine (6-BA) and 0.2 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), they consistently failed to differentiate into adventitious buds across all tested conditions, indicating an intrinsic morphogenic recalcitrance. In sharp contrast, juvenile hypocotyl explants successfully overcame this developmental block, establishing a complete and highly efficient callus-mediated whole-plant regeneration system. Among six tested combinations of 6-BA, 2,4-D, and kinetin on Murashige and Skoog (MS) medium, the combination of 2.0 mg/L 6-BA and 0.2 mg/L 2,4-D uniquely induced compact, actively dividing callus that spontaneously initiated bud primordia within 25 days, achieving the highest adventitious bud differentiation rate of 90.4 ± 2.5%. Regenerated shoots rooted most effectively on half-strength MS (1/2 MS) medium supplemented with 1.25 mg/L 1-naphthaleneacetic acid (NAA) and 0.75 mg/L indole-3-butyric acid (IBA), reaching a rooting rate of 95.2 ± 0.7%. Crucially, the entire developmental sequence from hypocotyl callus induction and de novo bud organogenesis to shoot elongation was coordinated on a unified single medium (2.0 mg/L 6-BA + 0.2 mg/L 2,4-D), substantially streamlining the operational process and enhancing multiplication efficiency. This robust protocol provides a practical pipeline for high-efficiency mass propagation and establishes an indispensable cellular foundation for future genetic transformation and molecular breeding in Bougainvillea.

Abstract: The Cactaceae represent one of the most diverse and threatened plant families worldwide, with Mexico constituting their principal center of diversity and endemism. Botanical gardens play a fundamental role in the ex situ conservation of this unique flora by maintaining living collections that support research, education, and species preservation. This study presents the first comprehensive taxonomic inventory and conservation assessment of the cactus collection maintained at the Botanical Garden of the Facultad de Estudios Superiores Cuautitlan, Universidad Nacional Autonoma de Mexico (UNAM). Between January 2024 and June 2025, all living specimens were inventoried and taxonomically verified, and their conservation status was evaluated according to the IUCN Red List, NOM-059-SEMARNAT-2010, and the CITES Appendices. The collection comprises 342 taxa belonging to 62 genera, including 259 native species, of which 215 are endemic to Mexico, and 83 exotic taxa. According to the IUCN Red List, most taxa were classified as Least Concern (180), although the collection also includes 106 threatened taxa, comprising 45 Vulnerable, 41 Endangered, and 20 Critically Endangered species. Additionally, 4 taxa are Near Threatened, 6 are Data Deficient, and 46 have not yet been evaluated. Under NOM-059-SEMARNAT, 65 taxa are listed as Endangered (P) and 47 are under Special Protection (Pr), highlighting the high conservation value of the collection at both national and international levels. These findings demonstrate that the FESC Botanical Garden houses an exceptional repository of Mexican cactus diversity and represents an important resource for ex situ conservation, scientific research, environmental education, and the long-term preservation of threatened plant genetic resources.

Abstract: Green compost is a promising peat substitute in container nursery production, but plant responses are often species-specific. This study evaluated three growing media containing 0, 36, and 72% (v/v) green compost, replacing none, half, or all of the peat fraction, combined with three fertilization protocols (unfertilized, organic, and organo-mineral), on growth, biomass, biomass allocation, and leaf macronutrients of Photinia × fraseri ‘Red Robin’ and Trachelospermum jasminoides. Fertilization was the main factor affecting growth in both species, with the organo-mineral protocol giving the highest values, whereas substrate composition did not affect aboveground growth. In Photinia, the highest compost proportion reduced root fresh weight and increased leaf K, Ca, and Mg concentrations, mainly under organic fertilization, without improving growth; unfertilized plants allocated more biomass to roots only in the peat-based substrate. In Star Jasmine, complete peat replacement did not reduce plant dry weight. However, root fresh weight decreased, and unfertilized plants in the peat-free substrate did not differ from fertilized ones. Green compost can therefore partly or fully replace peat for these species, provided that adequate fertilization is supplied. The compost pro-portion is adapted to the species.

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Traditional Brassica crops are valuable sources of bioactive compounds and contribute to the preservation of agricultural biodiversity. This study compared the phytochemical composition of two Apulian Brassica landraces, ‘Cavolo riccio’ (Brassica oleracea var. acephala) and ‘Cima di rapa di febbraio’ (Brassica rapa subsp. sylvestris), and evaluated the effects of boiling and steaming on their nutritional quality. Samples were analyzed in raw, boiled, and steamed forms for dry matter, polyphenols, flavonoids, phytosterols, photosynthetic pigments, anthocyanins, and glucosinolates. The two landraces showed complementary phytochemical profiles. ‘Cavolo riccio’ contained higher levels of dry matter, polyphenols, chlorophylls, carotenoids, and anthocyanins, whereas ‘Cima di rapa di febbraio’ was characterized by a substantially higher glucosinolate content. Phytosterol concentrations were similar in both landraces, averaging about 7 mg 100 g⁻¹ FW. Cooking significantly affected most bioactive compounds. Boiling caused the greatest reductions in dry matter, phenolic compounds, pigments, and glucosinolates, whereas steaming generally ensured higher retention. Total polyphenols decreased by 59% after boiling, while total glucosinolate content declined from 95.6 to 25.9 μmol kg⁻¹ FW. In contrast, steamed samples largely preserved glucosinolates and polyphenols, although reductions in flavonoids, carotenoids, and anthocyanins were still observed. Phytosterols were unaffected by thermal processing. These findings highlight the nutritional complementarity of the two Brassica landraces and identify steaming as the most suitable cooking method for preserving their nutraceutical value while supporting the valorization of local vegetable biodiversity.

Abstract: DNA-binding with One Finger (DOF) transcription factors play crucial roles in modulating plant growth, development, and environmental stress responses. However, the DOF family in flowering Chinese cabbage (Brassica campestris) remains poorly characterized. Here, 67 BcDOF genes were identified in B. campestris, distributed nonuniformly across ten chromosomes and classified into nine subfamilies. Structural analyses revealed that all BcDOF proteins harbor a conserved zinc-finger DOF (zf-DOF) domain, with members within individual subfamilies generally sharing similar motif architectures and exon-intron structures. Evolutionary analyses indicated that whole-genome triplication and segmental duplication were the major drivers of BcDOF family expansion, while purifying selection contributed to the evolutionary conservation of duplicated gene pairs. Promoter analysis revealed abundant cis-acting elements related to hormone signaling and abiotic stress responses. Quantitative real-time PCR (qRT-PCR) further demonstrated that many BcDOF genes responded to heat and drought stresses. Among them, BcDOF56 was markedly induced by both heat and drought and localized to the nucleus. Heterologous overexpression of BcDOF56 in Arabidopsis significantly improved heat and drought tolerance, as indicated by reduced malondialdehyde (MDA) accumulation and elevated superoxide dismutase (SOD) activity relative to wild-type (WT) plants. Collectively, these findings advance our understanding of the evolutionary and functional divergence of the BcDOF family and highlight BcDOF56 as a potential target for improving abiotic stress tolerance in B. campestris.

Abstract: TGA (TGACG motif-binding factor) proteins are plant-specific group D basic leucine zipper (bZIP) transcription factors that bind as-1/TGACG elements. They integrate jasmonic acid (JA) and salicylic acid (SA) signaling with growth, development and stress responses. Tea (Camellia sinensis) and oil tea (Camellia oleifera) are Theaceae crops grown for beverages and edible oil, and anthracnose, drought and chilling reduce their yield and quality. TGA genes had not been characterized in either crop. We therefore identified TGA genes ge-nome-wide in six representative Theaceae species: Camellia chekiangoleosa, C. oleifera, C. sinensis, Camellia crapnelliana, Camellia japonica and Stewartia sinensis. We then examined their phylogeny, gene structure and conserved motifs, codon usage, duplication and col-linearity, and promoter cis-elements. Transcriptome data and qRT-PCR provided expres-sion evidence for C. oleifera TGA (ColeTGA) genes after inoculation with Colletotrichum fruc-ticola. The survey yielded 68 non-redundant TGA genes, 10 to 13 per species, each with in-tact bZIP and DOG1 domains and a predicted nuclear localization. Phylogenetic analysis resolved five groups, and Theaceae members clustered mainly in Groups II and IV, where motif composition and exon–intron structure were conserved. Codon usage bias was weak (effective number of codons 52–54; codon adaptation index 0.77–0.80). The mean Ka/Ks was 0.25, indicating purifying selection. Whole-genome and segmental duplication drove most family expansion (60–91.67%), while tandem duplication was rare. Promoters were enriched in cis-elements responsive to light, JA, SA and abscisic acid (ABA). Expres-sion varied among tissues, and several genes were enriched in fruit and leaves. Salt, drought and cold each induced subsets of TGA genes. After inoculation with C. fructicola, the 12 ColeTGA genes showed four expression patterns. ColeTGA2, ColeTGA3, ColeTGA4, ColeTGA6, ColeTGA10 and ColeTGA12 were strongly activated. Together, these compari-sons clarify how TGA genes have been conserved and how they diverged among Theaceae lineages. They also identify candidates for functional tests of anthracnose resistance and for stress-tolerance breeding in tea and oil tea.

Abstract: In sustainable viticulture, inter-row vegetation management may improve biodiversity and influence grape quality, but the relationship among vegetation, pollinators, and grape quality still remains insufficiently researched. A three-year study was conducted in a vineyard in western Romania, to evaluate bare soil (BS), spontaneous vegetation (SV) and a multispecies cover crop mixture (CC) inter-row management practice, in terms of vegetation traits, pollinator groups, grape yield and quality in four cultivars. Vegetation cover, flower density and plant species richness were recorded; pollinators were sampled using transects and classified into five groups; grape quality parameters, phenolic compounds, and anthocyanins (red cultivars), were measured at harvest time. CC had consistently the highest vegetation cover, flower density and species richness, whereas BS had the lowest values. Plant diversity explained over 92% of the variation in total pollinator abundance, whereas inter-row management accounted for 76% of differences in pollinator group compositions. Multivariate analyses showed a trade-off: BS favoured yield-related traits while CC enhanced phenolic and anthocyanin accumulation. Quality parameters were well described by full-factorial models (R² ranging from 0.799 to 0.996). Cover crop mixtures may serve as multifunctional tools to increase biodiversity and grape quality, but potential competition for resources should be considered. Inter-row vegetation management is a promising approach to reconcile ecological and oenological goals, with cultivar- and season-specific responses warranting further investigation.

Abstract: Diaporthe species are important fungal pathogens associated with canker and dieback diseases of woody plants, but genomic factors underlying differences in pathogenicity among pear-associated species remain poorly understood. In this study, D. amygdali DUCC20226 and D. eres DUCC15256 were isolated from canker-affected Asian pear (Pyrus pyrifolia) in Korea, representing the first reports of both species causing pear canker in the country. Pathogenicity assays showed that D. amygdali caused more severe symptoms than D. eres on pear seedlings. High-quality genome assemblies were generated for D. amygdali (49.82 Mb) and D. eres (61.16 Mb), with BUSCO completeness of 98.9% and 98.7%, respectively. Comparative genomic analysis revealed substantial genomic conservation, although species-specific genes included predicted secreted proteins and candidate ef-fectors. Notably, D. amygdali possessed species-specific putative necrosis-inducing ef-fectors, whereas D. eres contained more carbohydrate-active enzymes (961 vs. 863) and biosynthetic gene clusters (116 vs. 87). Mitochondrial genomes differed markedly in size, measuring 49,922 bp in D. amygdali and 93,346 bp in D. eres, despite conserved core gene composition. Phylogenetic analysis based on 15 mitochondrial protein-coding genes placed both isolates within Diaporthaceae. These results provide genomic resources for pear-associated Diaporthe species and insights into potential genetic factors underlying pathogenic specialization.

Abstract: The demand for year-round production of high-quality crops has increased interest in plant factories with artificial lighting (PFALs). However, artificial lighting is a major energy demand in indoor production. This systematic review synthesizes evidence on the effects of LED spectral composition, photosynthetic photon flux density (PPFD), photoperiod, and daily light integral (DLI) on basil (Ocimum basilicum L.). The review focused on growth, quality, and energy-use efficiency. The review followed PRISMA 2020 guidelines. Sixty peer-reviewed studies were included from Web of Science, Scopus, ScienceDirect, and Google Scholar. Red-blue and broadband spectra supported high biomass production. Blue, ultraviolet, and selected far-red treatments modified phytochemical, essential oil, morphological, and quality traits. These responses varied with cultivar and lighting conditions. DLI influenced biomass and light-use efficiency. However, similar DLI values produced different responses when PPFD and photoperiod differed. Higher light inputs also did not consistently produce proportional gains in biomass or energy-use efficiency. Overall, efficient basil production requires coordinated management of spectrum, PPFD, DLI, photoperiod, cultivar, and production stage. An integrated lighting optimization framework is proposed to balance crop productivity, quality, and energy-use efficiency in PFALs.

Abstract: Grapholita funebrana is an important pest of plum orchards whose seasonal activity is strongly influenced by environmental conditions. This study evaluated adult flight dynamics in a ‘Stanley’ plum orchard in northeastern Romania during 2025–2026 and examined their relationships with temperature and thermal accumulation. Adults were monitored using AtraFUN pheromone traps in two orchard management systems: conventional chemical management and management without chemical insecticide treatments. Seasonal captures differed markedly between years and systems, totaling 1956 adults in 2025 and 1157 in 2026, while the main flight peaks consistently occurred during the first half of June. In 2025, no significant relationships were detected between captures and temperature. In contrast, significant positive associations were observed in 2026, with the strongest Spearman correlations obtained for mean temperature over the five-day period ending on each monitoring date (ρ = 0.765 and 0.774 for the chemical and untreated systems, respectively; p < 0.001). Analysis of cumulative captures against growing degree-days revealed substantial interannual variability in thermal thresholds. These findings indicate that short-term thermal conditions and heat accumulation can complement pheromone monitoring for characterizing local Grapholita funebrana phenology, although multi-year validation is required before their use as operational forecasting thresholds.

Abstract: Hibiscus syriacus L. is a landscape plant with ornamental, economic, and ecological value. However, the low natural fruit-setting rate observed in most cultivars significantly hinders its cross-breeding, germplasm innovation, and large-scale application. In this study, we analysed 20 cultivars to identify the key floral traits associated with H. syriacus fertility. Fifty floral phenotypic and pollen morphological indicators were systematically quantified, fruit-setting and pollen vitality rates were recorded, and insect foraging behaviours were observed to assess the diversity of floral characteristics and their correlation with fertility. The results showed that notable variations in floral phenotype and pollen morphology exist among the studied cultivars. Pollen grains were characterised by spinous ornamentation, with notable differences in grain size, spine morphology, and surface wrinkling. Correlation analysis identified 9 core floral and palynological indicators that are highly associated with H. syriacus fertility. These comprise five floral phenotypic variables, such as pistil length (PL2) and heart length (HL), and four microscopic palynological features, including thorn curvature (TC) and spine number (TN). In this study, we established a phenotypic and palynological framework for understanding fruit-setting in H. syriacus. These 9 core metrics have the potential to serve as morphological markers for the rapid evaluation of hybrid parents, thereby providing a scientific basis for genetic improvement, cultivar breeding, and the industrial expansion of this species.

Abstract: Pea (Pisum sativum L.) is an important grain legume crop with significant nutritional, agronomic and ecological value. Given the rise of salt affected soils and restricted water resources, improving salinity tolerance is becoming increasingly important. This study estimated the impact of increasing soil salinity on plant development and yield-related traits of five pea genotypes cultivated under controlled vertical farming conditions. Plants were exposed to four salinity treatments comprising a non-saline control (0 mM NaCl) and three salinity levels (100, 150 and 200 mM NaCl). The results showed that genotypes were the main source of variation for most observed traits, while salinity treatment also significantly affected several yield-related traits. Moderate salinity levels (100–150 mM NaCl) did not uniformly reduce plant performance and, in several genotype cycle combinations, resulted in numerical increases in yield-related and biomass traits. In contrast, the highest salinity level (200 mM NaCl) caused the most pronounced reductions in the evaluated traits, with maximum decreases of 42.4% in pod length, 73.8% in seed weight per plant, and 71.9% in fresh biomass. Genotype Favorit showed the highest overall stability, genotype Vilo exhibited the strongest decline in yield traits, while genotype Virtus exibited the greatest sensitivity in biomass under severe salinity. These results indicate significant genetic variability in salinity tolerance and identify promising genotypes for breeding programs and production in salinity affected soils and environments. Furthermore, the study confirms that a controlled vertical farming system provides a reliable, reproducible platform for soil salinity impact assessment and genotype evaluation, supporting the development of salt-tolerant pea cultivars.

Abstract: The demand for uniform and high-yielding vegetable varieties has accelerated the erosion of vegetable biodiversity and the marginalisation of local adapted plant genetic resources (PGR) and landraces that do not meet conventional registration standards. This review critically evaluates the European Amateur Varieties (AVs) regime as a regulatory pathway for the conservation and commercialisation of local PGR. Based on the European Common Catalogue (CC), 1,284 AVs were identified (5.5% of all vegeta-ble varieties listed in the CC), with a markedly uneven distribution across countries and maintainers. France accounted for 23.1% of European AVs, followed by Germany (20.2%) and the Netherlands (13.6%). Most AVs (79%) were registered by private maintainers, while the presence of public institutions and third-sector maintainers highlight the regime’s dual function: on the one hand, it supports the commercialisa-tion of low-yielding varieties in niche markets; on the other, it may facilitate the mar-keting and conservation of landraces. A detailed analysis of Italian AVs further clarifies this pattern: of the 85 AVs registered in Italy or by Italian maintainers abroad, 79% were commercial varieties or F1 hybrids, while 21% were local landraces. In addition, 40% of Italian AVs were registered by maintainers based abroad, mainly in Israel, Spain, and Japan. Overall, the AVs regime addresses multiple needs but has limited impact on the European seed market. Greater coordination with the Conservation Va-rieties (CVs) regime could strengthen the conservation, protection, and valorisation of landraces and local PGR.

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This study examines the competitive interactions between common bean (Phaseolus vulgaris L.) and two problematic weed species, Amaranthus palmeri S. Watson (Palmer amaranth) and Ipomoea purpurea L. (common morningglory), using a replacement series design. The analysis evaluates important competition indices namely relative yield (RY), total relative yield (TRY), and key growth parameters, height and biomass produced by the crop and weeds, along with common bean yield components (i.e., pods per plant, seeds per pod, and pod weight) across the varying proportions of crop-to-weed ratios (100:0, 75:25, 50:50, 25:75, and 0:100). Results demonstrate that I. purpurea exerts significantly greater competitive pressure than A. palmeri, with significant suppression of common bean yield at high weed densities. Total relative yield analysis reveals overyielding at the 50:50 proportion, suggesting niche differentiation or competitive equivalence between species. Yield component analysis indicates that weed competition primarily reduces pod number per plant, with secondary effects on seed set and pod biomass. These findings have provided insights into common bean-weed competition while exerting important implications for integrated weed management strategies in bean production systems.

Abstract: Canistel (Pouteria campechiana (Kunth) Baehni) is a tropical evergreen fruit tree native to Mesoamerica and increasingly cultivated in southern China for its high-value, nutrient-dense fruits. Despite growing commercial interest, comprehensive knowledge of this species remains fragmented. This review systematically synthesizes current research on canistel, covering its botanical characteristics, germplasm resources, propagation and cultivation techniques, nutritional composition, phytochemical diversity, pharmacological bioactivities, and food processing applications. The fruit is rich in carbohydrates, carotenoids (particularly lycopene and β-carotene), phenolic compounds (including gallic acid, catechin, and myricitrin), and essential minerals, while the seeds represent an underutilized source of high-amylose starch (up to 68.1%) with superior thermal stability. Pharmacological studies have demonstrated significant antioxidant, anti-inflammatory, hepatoprotective, analgesic, and immunomodulatory activities, largely attributable to its polyphenolic and triterpenoid constituents. Recent advances in encapsulation and oil-based fortification have improved the stability and bioaccessibility of canistel carotenoids, opening new avenues for functional food development. However, critical research gaps remain, including limited germplasm characterization, insufficient molecular breeding tools, narrow product diversification, and a lack of long-term toxicological and clinical data. This review identifies these challenges and proposes future research directions to facilitate the sustainable industrial development of canistel.

Abstract: Common bean (Phaseolus vulgaris L.) is the world’s most widely consumed grain legume and a foundational species for organic and low-input agriculture, yet its agroecological value extends far beyond nitrogen fixation and nutritional provisioning. This review reframes P. vulgaris as a breeding target defined by ecosystem function rather than by yield alone, synthesizing evidence on functional biology, biological nitrogen fixation, rhizosphere microbiome assembly and soil ecosystem engineering to identify the trait complexes that ecosystem-oriented breeding programs must select for. We examine the constraints limiting expression of these traits under organic management, including weed competition, biotic and abiotic stress, nutrient limitation and the scarcity of cultivars and certified seed adapted to low-input environments, and evaluate the agroecological management practices, resource-use efficiency metrics and emerging technologies, spanning precision agriculture, phenomics, molecular breeding, genome editing and microbiome engineering, that can accelerate their genetic improvement. Central to this synthesis is a paradigm shift in breeding objectives: common bean is conceptualized as a holobiont whose performance emerges from coordinated plant-microbiome interaction, requiring breeding programs to select explicitly for nitrogen-fixation efficiency, root system architecture, rhizosphere recruitment capacity, nutrient-use efficiency and multi-stress resilience as heritable, ecosystem-oriented traits. We conclude by outlining priority breeding research directions integrating genomics, phenomics, envirotyping and rhizosphere ecology, positioning common bean breeding as a strategic lever for the transition toward regenerative, climate-smart organic agriculture.

Abstract: This study evaluated deficit irrigation (DI; 55% of crop evapotranspiration (ETc) from BBCH 76 to four days after harvest, followed by rewatering) compared with full irriga-tion (FI; 100% ETc) in ‘Regina’ trees. DI reduced soil water, tree water status, light-saturated photosynthesis (ASAT) and stomatal conductance (gs). However, temporal changes in ASAT were weakly related with leaf water potential (ΨL) and closely related to gs and mesophyll conductance (gm). DI modified non-structural carbon partitioning in leaves, increasing sorbitol concentration by 27% and decreasing sucrose by 57% without affecting total soluble sugars. At the same time, lignin fluorescence decreased under DI whereas leaf mass per area (LMA) and stomatal density remained unaffected. After harvest and rewatering, ΨL increased in both treatments, but leaf gas exchange activity dropped accompanied by increases in lignin fluorescence and LMA. Despite an 8% de-crease in fruit size, fruit yield was maintained, improving water productivity by 67%. Our results indicate that sweet cherry responses to DI are not solely determined by water status, but also involve carbon partitioning, leaf structural traits and source-sink dy-namics, allowing yield to be maintained at the expense of fruit size.

Abstract: Future International Space Station (ISS) mini-gardens must provide fresh produce repeatedly while maintaining water and nutrient conditions within a small, reusable root-zone volume. This study evaluated the operational performance of staggered planting and selective harvesting over four months in a ground-based Utah Reusable Root Module (URRM) simulator operated as a zero-discharge system. Five independent root modules (RMs), providing a total planted area of approximately 0.40 m², were planted with leafy greens, bonsai basil, and dwarf tomato. The system produced 4,299 g of fresh edible biomass, with produce available on 77 of the 100 days within the harvest period. Daily water use remained below approximately 2 L d⁻¹ for most of the trial, and peak demand occurred at different times among RMs. RMs containing established tomato plants behind newly planted leafy greens showed lower water-use peaks and biomass production, suggesting incomplete use of module capacity. Lettuce performed well during the first cycle but was less consistent in subsequent cycles, whereas mizuna and kale provided more consistent production under reused-media conditions. Bulk electrical conductivity (bulk EC) declined during periods of rapid crop growth, indicating that nutrient depletion, rather than salinity accumulation, was the main root-zone risk under zero-discharge operation. These results indicate that ISS mini-garden operations can distribute harvests and water demand over time, but crop calendars should coordinate planting dates, crop architecture, harvest timing, residue management, reused-media constraints, and root-zone nutrient monitoring across independently managed modules.

Abstract: Pholidota chinensis is an orchid with both medicinal and ornamental value. Due to overharvesting and limited natural reproduction, its wild populations have declined sharply. Although aseptic sowing enables large-scale propagation, climate-driven extreme heat poses a threat to seedling production. However, the physiological responses and propagation potential of P. chinensis seedlings under heat stress remain poorly understood. This study examined six-month-old seedlings under four temperatures (34℃, 36℃, 38℃, 40℃) for up to 96 h. Photosynthetic performance was assessed via UV-Vis spectroscopy and chlorophyll fluorescence (Fv/Fm), and propagation potential via stem segment regeneration. Unexpectedly, high-temperature stress induced a non-monotonic and temperature-specificpattern of pigment alteration: 34℃ reduced total chlorophyll to ~40% of initial value, whereas 36℃, 38℃, and 40℃ maintained 70%–95%, revealing that pigment content did not decline monotonically with increasing temperature. Pigment degradation became increasingly synchronized at higher temperatures, with chlorophyll b and carotenoid absorbance strongly correlated with chlorophyll a peaks (r > 0.85–0.90, P < 0.01). In contrast, Fv/Fm declined in a strictly temperature-dependent manner, from 0.74 to 0.50 (34℃), 0.45 (36℃), 0.41 (38℃), and 0.25 (40℃) at 96 h. Notably, 36℃ showed signs of partial PSII recovery, while the 36–38℃ range represented a critical transition zone, with 38℃ showing sustained suppression without clear recovery. Fv/Fm correlated strongly with proliferation coefficient (r > 0.85, P < 0.01), with proliferation severely compromised below Fv/Fm = 0.40 and completely lost at 0.25. These findings demonstrate that pigment content and photosynthetic functionality respond to heat stress through distinct mechanisms in P. chinensis seedlings. The strong Fv/Fm–regenerative capacity correlation supports chlorophyll fluorescence as a rapid, non-destructive indicator for early stress diagnosis and heat-tolerant material screening.