Water Stress Conditions Research Articles

Growth and antioxidant responses to water stress in eggplant MAGIC population parents, F1 hybrids and a subset of recombinant inbred lines

BackgroundThe generation of new eggplant (Solanum melongena L.) cultivars with drought tolerance is a main challenge in the current context of climate change. In this study, the eight parents (seven of S. melongena and one of the wild relative S. incanum L.) of the first eggplant MAGIC (Multiparent Advanced Generation Intercrossing) population, together with four F1 hybrids amongst them, five S5 MAGIC recombinant inbred lines selected for their genetic diversity, and one commercial hybrid were evaluated in young plant stage under water stress conditions (30% field capacity; FC) and control conditions (100% FC). After a 21-day treatment period, growth and biomass traits, photosynthetic pigments, oxidative stress markers, antioxidant compounds, and proline content were evaluated.ResultsSignificant effects (p < 0.05) were observed for genotype, water treatments and their interaction in most of the traits analyzed. The eight MAGIC population parental genotypes displayed a wide variation in their responses to water stress, with some of them exhibiting enhanced root development and reduced foliar biomass. The commercial hybrid had greater aerial growth compared to root growth. The four F1 hybrids among MAGIC parents differed in their performance, with some having significant positive or negative heterosis in several traits. The subset of five MAGIC lines displayed a wide diversity in their response to water stress.ConclusionThe results show that a large diversity for tolerance to drought is available among the eggplant MAGIC materials, which can contribute to developing drought-tolerant eggplant cultivars.

Performance of ACCase-Resistant and ACCase-Susceptible Phenotypes of Sterile Oat Avena sterilis subsp. ludoviciana (Durieu) Nyman under Drought Conditions in the Greenhouse

Climate change might benefit water-stress-adapted weeds, further impairing their management. To evaluate the impact of soil moisture regimes on the growth and reproductive behaviour of ACCase-resistant and ACCase-susceptible phenotypes of sterile oat (Avena sterilis subsp. ludoviciana (Durieu) Nyman), a greenhouse experiment was carried out in 2020 and 2021. The factors were soil moisture regimes (100% field capacity (FC) as well-watered, 75% FC, 50% FC, and 25% FC) and ACCase-resistant and ACCase-susceptible phenotypes of sterile oat. Increased drought stress conditions reduced the number of tillers per plant by 34, 55, and 83% and the number of seeds per plant by 36, 61, and 89% in the 75% FC, 50% FC, and 25% FC conditions, respectively, compared to the well-watered treatment. Notably, both phenotypes reacted similarly to water stress, with no interactions between the two factors. Regardless of water stress, the resistant phenotypes produced fewer seeds per plant, indicating fitness costs. However, due to their high plasticity, both phenotypes will still produce seeds even when facing severe water stress conditions. Thus, sterile oat is expected to continue infesting crop fields in the near future, but with ACCase-resistant phenotypes being less successful than susceptible ones in the absence of herbicide application.

Amelioration of the Detrimental Effects of Water Deficit Stress on Lentil (Lens culinaris Medik) Through the Utilization of Poultry Litter-Based Compost

It is critical that Bangladesh faces water scarcity during the dry season, affecting lentil (Lens culinaris Medik.) yield and some yield components during seedling and flowering stages. Thus, a two-factorial pot experiments (The experiment comprises Factor A: three fertilization levels i.e. F1 = Control [inorganic], F2 = poultry litter-based compost [20 ton/ha], F3 = poultry litter-based compost [30 ton/ha]; Factor B: two irrigation levels such as W1 = 100% field capacity [FC] and W2 = 70% FC) were designed at Hajee Mohammad Danesh Science and Technology University, Dinajpur, from November 2018 to April 2019. And it was investigated how the poultry litter-based composts affected the morpho-physiology, yield and yield components of the lentil (BARI Masur-4) variety under different irrigation stress levels. Obtained results revealed that the tallest plant (30.7 cm at 75 DAS) and maximum branch number per plant (14.1 at 65 DAS), leaf chlorophyll a (0.30 mg/g), highest RLWC (70.28%), lowest proline content (1.57 µ moles g-1 FW), maximum number of pods per plant (39.4 at 75 DAS) and total grain yield (3.62 kg/m2) were recorded from compost F3 (poultry litter-based compost 30 tons/ha) with W1 (100% FC). Results also showed that the yield contributing attributes and yield of lentils were drastically reduced by water stress conditions with different rates of fertilization. In drought conditions (W2 = 70% FC), F3 (30 ton/ha poultry litter-based compost) fertilization produced the highest plant height (30.20 cm at 75 DAS), number of branches (11.5 at 65 DAS), stem dry weight (0.35 g), lowest proline (3.88 µ moles g-1 FW), highest pod number per plant (33.1), weight of 100-seed (2.36 g), total grain weight (2.77 kg/m2), harvest index (58.84%) compared to other fertilizations (F1 and F2). In summary, F3 (30 tons), a compost made from poultry litter, provides better soil conditions under drought conditions compared to F1 and F2 in the year of 2018-19 at the 0 and 20 tons/ha, respectively under the field conditions.

Does late water deficit induce root growth or senescence in wheat?

In crops like wheat, terminal drought is one of the principal stress factors limiting productivity in rain-fed systems. However, little is known about root development after heading, when water uptake can be critical to wheat crops. The impact of water-stress on root growth was investigated in two wheat cultivars, Scout and Mace, under well-watered and post-anthesis water stress in three experiments. Plants were grown outside in 1.5-m long pots at a density similar to local recommended farming practice. Differences in root development were observed between genotypes, especially for water stress conditions under which Scout developed and maintained a larger root system than Mace. While under well-watered conditions both genotypes had shallow roots that appeared to senesce after heading, a moderate water stress stimulated shallow-root growth in Scout but accelerated senescence in Mace. For deep roots, post-heading biomass growth was observed for both genotypes in well-watered conditions, while under moderate water stress, only Scout maintained net growth as Mace deep roots senesced. Water stress of severe intensity affected both genotypes similarly, with root senescence at all depths. Senescence was also observed above ground. Under well-watered conditions, Scout retained leaf greenness (i.e. stay-green phenotype) for slightly longer than Mace. The difference between genotypes accentuated under moderate water stress, with rapid post-anthesis leaf senescence in Mace while Scout leaf greenness was affected little if at all by the stress. As an overall result, grain biomass per plant ('yield') was similar in the two genotypes under well-watered conditions, but more affected by a moderate stress in Mace than Scout. The findings from this study will assist improvement in modelling root systems of crop models, development of relevant phenotyping methods and selection of cultivars with better adaptation to drought.

Germination Performance of Physalis peruviana L. Seeds under Thermal and Water Stress Conditions

Physalis peruviana holds significant economic value, making it crucial to determine optimal cultivation conditions, particularly concerning seed germination under varying water and temperature conditions. Therefore, this study aimed to assess the impacts of heat and water stress on the germination and vigor of P. peruviana seeds. The study was divided into two trials: the first examined the effect of constant temperatures of 10, 15, 20, 25, 30, 35, and 40 °C and alternating temperatures of 20 °C during the dark period and 30 °C during the light period (control) on seed germination and vigor. The second trial investigated germination and vigor under different water and thermal conditions using various osmotic potentials (0; −0.3; −0.6; and −0.9 MPa) and two temperatures (constant 30 °C and alternating 20 °C during the dark period and 30 °C during the light period). Both trials used a 16 h photoperiod. The germination tests revealed optimal (30 °C), moderate (20/30 °C), minimal (20 °C), and inhibited (40 °C) temperatures for the species’ germination. It was found that the first germination count could be conducted on the seventh day after sowing. Low water availability had negative effects on seed germination and vigor, especially at osmotic potentials below −0.45 and −0.61 MPa, combined with temperatures of 30 and 20/30 °C, respectively. Severe water stress, with osmotic potentials equal to or below −0.9 MPa, completely inhibited seed germination and vigor. Reduction in water potential and increased temperature resulted in a significant decrease in the percentage, speed, and quality of P. peruviana germination. These findings indicate that the species does not tolerate extreme temperatures, whether low (less than 15 °C) or high (greater than 35 °C), nor water stress with osmotic potentials lower than −0.45 MPa, much less the combination of these factors.

Growth and morpho-physiological assessments of Indonesian red chili cultivars on early vegetative stage under water stress conditions: A comparison of waterlogging and drought

Growth and morpho-physiological assessments of Indonesian red chili cultivars on early vegetative stage under water stress conditions: A comparison of waterlogging and drought

Effects of Magnetized, Chelated Iron Foliage Treatments, and Metal Halide Lamps on Plant Water Structure, Water Vapor Dynamics, and Resilience for Legumes under Water Stress

A greenhouse study was conducted to determine the effects of foliar applications of magnetized, chelated liquid iron fertilizer for increasing the drought tolerance of two legumes. The study objectives were to determine the drought tolerance effects of four treatments on foliar gas exchange, soil moisture, and plant growth for soybean (Glycine max) and velvet bean (Mucuna pruriens) plants. The plant treatments included applications with chelated liquid iron fertilizer (2.5 and 5%) with a conventional boom sprayer, with and without magnets in the spray lines, and metal halide lamps. Three gas exchange measurements were collected before applying the foliage treatments and after two water stress treatments. A foliage and metal halide lamp treatment deactivated or unlinked nine interconnected gas exchange parameters that are correlated with plant defense activities during water stress conditions. The deactivation of interconnected regulatory gas exchange functions improved metabolic efficiency, reduced stress levels, and boosted plant resilience to abiotic stressors. Also, the study findings suggest that the study treatments maintained or increased the level of biologically structured water in plant tissues and vascular systems.

A New Remote Sensing Index for Forest Dryness Monitoring Using Multi-Spectral Satellite Imagery

Canopy water content is a fundamental indicator for assessing the level of plant water stress. The correlation between changes in water content and the spectral reflectance of plant leaves at near-infrared (NIR) and short-wave infrared (SWIR) wavelengths forms the foundation for developing a new remote sensing index, the Infrared Canopy Dryness Index (ICDI), to monitor forest dryness that can be used to predict the consequences of water stress. This study introduces the index, that uses spectral reflectance analysis at near-infrared wavelengths, encapsulated by the Normalized Difference Infrared Index (NDII), in conjunction with specific canopy conditions as depicted by the widely recognized Normalized Difference Vegetation Index (NDVI). Development of the ICDI commenced with the construction of an NDII/NDVI feature space, inspired by a conceptual trapezoid model. This feature space was then parameterized, and the spatial region indicative of water stress conditions, referred to as the dry edge, was identified based on the analysis of 10,000 random observations. The ICDI was produced from the combination of the vertical distance (i.e., under consistent NDVI conditions) from an examined observation to the dry edge. Comparisons between data from drought-affected and non-drought-affected control plots in the Australian Northern Jarrah Forest affirmed that the ICDI effectively depicted forest dryness. Moreover, the index was able to detect incipient water stress several months before damage from an extended drought and heatwave. Using freely available satellite data, the index has potential for broad application in monitoring the onset of forest dryness. This will require validation of the ICDI in diverse forest systems to quantify the efficacy of the index.

Integration of Horse Manure Vermicompost Doses and Arbuscular Mycorrhizal Fungi to Improve Fruit Quality, and Soil Fertility in Tomato Field Facing Drought Stress.

Climate change poses major challenges for agriculture in arid and semi-arid regions, with drought conditions severely affecting water-intensive crops such as tomatoes. This study evaluates the efficacy of organic amendments, derived from horse manure, and arbuscular mycorrhizal fungi (AMF) on enhancing tomato (Solanum lycopersicum L.) fruit quality and soil health under semi-arid field conditions. The experimental design included two irrigation regimes (well-watered and drought stress) and two levels of vermicompost application (C1 5 t ha-1 and C2 10 t ha-1), applied individually or in combination with AMF. The results indicate that drought stress reduced tomato fruit growth and yield, while osmoprotectant accumulation, antioxidant enzyme activity, and bioactive compound levels increased, and the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of tomato fruit also increased. Notably, the biostimulants application, especially (C1+AMF), counteracted the adverse effects of drought, compared to the control, by significantly enhancing fruit yields (60%), as well as increasing ascorbic acid levels (59%) and free amino acids content (90%). These treatments also improved the activity of bioactive compounds and nutrient uptake in the fruit. Furthermore, biostimulant application positively affected the physicochemical properties of soil. The results obtained confirm that the application of biostimulants can be suitable for improving crop sustainability and adaptability under conditions of water stress in semi-arid field regions.

Proline Metabolism in Response to Climate Extremes in Hairgrass

Hairgrass (Deschampsia caespitosa), a widely distributed grass species considered promising in the ecological restoration of degraded grassland in the Qinghai-Xizang Plateau, is likely to be subjected to frequent drought and waterlogging stress due to ongoing climate change, further aggravating the degradation of grassland in this region. However, whether it would acclimate to water stresses resulting from extreme climates remains unknown. Proline accumulation is a crucial metabolic response of plants to challenging environmental conditions. This study aims to investigate the changes in proline accumulation and key enzymes in hairgrass shoot and root tissues in response to distinct climate extremes including moderate drought, moderate waterlogging, and dry–wet variations over 28 days using a completely randomized block design. The proline accumulation, contribution of the glutamate and ornithine pathways, and key enzyme activities related to proline metabolism in shoot and root tissues were examined. The results showed that water stress led to proline accumulation in both shoot and root tissues of hairgrass, highlighting the importance of this osmoprotectant in mitigating the effects of environmental challenges. The differential accumulation of proline in shoots compared to roots suggests a strategic allocation of resources by the plant to cope with osmotic stress. Enzymatic activities related to proline metabolism, such as Δ1-pyrroline-5-carboxylate synthetase, ornithine aminotransferase, Δ1-pyrroline-5-carboxylate reductase, Δ1-pyrroline-5-carboxylate dehydrogenase, and proline dehydrogenase, further emphasize the dynamic regulation of proline levels in hairgrass under water stress conditions. These findings support the potential for enhancing the stress resistance of hairgrass through the genetic manipulation of proline biosynthesis and catabolism pathways.

Genomic loci associated with grain yield under well-watered and water-stressed conditions in multiple bi-parental maize populations

Smallholder maize farming systems in sub-Saharan Africa (SSA) are vulnerable to drought-induced yield losses, which significantly impact food security and livelihoods within these communities. Mapping and characterizing genomic regions associated with water stress tolerance in tropical maize is essential for future breeding initiatives targeting this region. In this study, three biparental F3 populations composed of 753 families were evaluated in Kenya and Zimbabwe and genotyped with high-density single nucleotide polymorphism (SNP) markers. Quantitative trait loci maping was performed on these genotypes to dissect the genetic architecture for grain yield (GY), plant height (PH), ear height (EH) and anthesis-silking interval (ASI) under well-watered (WW) and water-stressed (WS) conditions. Across the studied maize populations, mean GY exhibited a range of 4.55–8.55 t/ha under WW and 1.29–5.59 t/ha under WS, reflecting a 31–59% reduction range under WS conditions. Genotypic and genotype-by-environment (G × E) variances were significant for all traits except ASI. Overall broad sense heritabilities for GY were low to high (0.25–0.60). For GY, these genetic parameters were decreased under WS conditions. Linkage mapping revealed a significant difference in the number of QTLs detected, with 93 identified under WW conditions and 41 under WS conditions. These QTLs were distributed across all maize chromosomes. For GY, eight and two major effect QTLs (&amp;gt;10% phenotypic variation explained) were detected under WW and WS conditions, respectively. Under WS conditions, Joint Linkage Association Mapping (JLAM) identified several QTLs with minor effects for GY and revealed genomic region overlaps in the studied populations. Across the studied water regimes, five-fold cross-validation showed moderate to high prediction accuracies (−0.15–0.90) for GY and other agronomic traits. Our findings demonstrate the polygenic nature of WS tolerance and highlights the immense potential of using genomic selection in improving genetic gain in maize breeding.

Physiological quality of sunflower seeds under water stressed conditions

Water is one of the factors that most influences the seed germination process; however, its excess can cause injuries to cell membranes due to rapid imbibition. On the other hand, water restriction limits seed germination, promoting a reduction in cell water potential that disrupts physiological and metabolic reactions. Thus, the objective of this study was to evaluate the physiological quality of sunflower seeds subjected to water stress induced by polyethylene glycol 6000 (PEG 6000). The experimental design used was completely randomized, consisting of six treatments consisting of osmotic potentials (0; -0.3; -0.6; -0.9; -1.2; and -1.5 MPa) simulated with aqueous solutions of PEG 6000. Germination, radicle protrusion, first count, germination speed index, abnormal seedlings, shoot length, and root length were evaluated. Water stress induced by PEG 6000 solutions affects the physiological quality of sunflower seeds, being proportional to the reduction of osmotic potential. Germination and seed vigor decrease under water stress conditions from an osmotic potential of -0.4 MPa, with the most negative potentials (-1.2 and -1.5 MPa) preventing seed germination.

Water flow in two Cactaceae species: standardization of the method and test under different drought conditions

AbstractInvestigating water flow in the vascular system of plants is important to identify the water path and conduction capacity of different plant species, mainly in succulent species living in dry regions. This study aimed to standardize a method to track water flow in the xylem of Mammillaria bocasana and Echinocereus reichenbachii var. fitchii (Cactaceae) and test it under different drought conditions. The plants were kept under greenhouse conditions to perform the split root method, water flow tracing, and different drought treatments. The plants of each species were separated into three treatments: constant irrigation, drought with water and dye, and drought with dye. Plants were cut 24 h after staining, total and lumen diameters were taken, and the relative theoretical hydraulic conductivity was calculated. The absorption method was adequate for the tracing of water flow, and it worked in all the treatments of the drought experiment. Conducting elements, including wide-band tracheids, were stained violet and were located near the vascular cambium. In Mammillaria bocasana, half of the vascular cylinder was stained, while in Echinocereus reichenbachii var. fitchii, the entire cylinder was stained due to the cortical bundles. M. bocasana had a higher lumen diameter and relative theoretical hydraulic conductivity than E. reichenbachii var. fitchii. With the absorption staining method, the flow of water was traced, and differences in conduction under water stress conditions between the two species of cacti were detected. These results suggest that cacti species living under water stress solve the water movement in different ways.

Response of tropical forest productivity to seasonal drought mediated by potassium and phosphorus availability

Tropical forest productivity is increasingly reported to be nutrient limited, which may affect its response to seasonal droughts. Yet experimental evidence on nutrient limitation from Afrotropical forests remains rare. We conducted an ecosystem-scale, full factorial nitrogen (N)–phosphorus (P)–potassium (K) addition experiment in a moist forest in Uganda to investigate nutrient controls on fine litter production and foliar chemistry. The eight factorial treatments were replicated four times in 32 plots of 40 × 40 m each. During the three-year nutrient additions, we found K and P limitations on leaf litter production, exhibiting strong links to ecosystem responses to seasonal drought. Specifically, leaf litterfall consistently decreased in dry seasons with K additions, whereas P additions caused a reduction only during prolonged drought in the first year. Leaf litterfall was not significantly affected by N additions. Furthermore, K additions delayed the timing of leaf litterfall peak, underscoring the crucial role of K in regulating stomatal aperture and signalling during water-stress conditions and suggesting a prolonged leaf lifespan. Foliar N increased with N and P additions whereas K was the most resorbed nutrient. We conclude that the productivity and resilience of tropical forests, particularly under drier conditions, may depend on terrestrial K and P availability.

Effect of potassium humate spray on some biochemical characteristics in potato leaves Solanum tuberosum under water stress conditions

نفذت الدراسة في محطة بحوث الهنادي التابعة لمركز البحوث العلمية الزراعية في اللاذقية خلال العروة الربيعية لموسم 2020 وذلك لدراسة تأثير الرش الورقي بتراكيز متباينة من هيومات البوتاسيوم 1500,1000,500 ppm على نباتات البطاطا صنف سبونتا عند مستويي ري 40و80 % من السعة الحقلية . استخدم في تصميم التجربة نظام العشوائية الكاملة ضمن القطع المنشقة. شملت التجربة 4 معاملات و3 مكررات لكل معاملة عند كل مستوى رطوبة. تم رش النباتات بالهيوماتHA بعد 35 يوم من الزراعة لثلاثة مرات، بفاصل عشرة أيام بين الرشة والأخرى. أظهرت النتائج زيادة محتوى السكريات الذائبة الكلية ومحتوى البرولين وفعالية الكاتالاز في أوراق البطاطا المجهدة في حين انخفض محتواها من الكلوروفيل .كما حسنت المعاملة بهيومات البوتاسيوم الصفات المدروسة عند المستوى 40 % ، وأعطت معاملة الهيومات بتركيز1000 ppm أعلى محتوى من الكلوروفيل الكلي 0.142مليمول / مغ ، والسكريات الذائبة الكلية1.67ملغ/غ . بينما أعطت معاملة الهيومات بتركيز 1500 ppm أعلى محتوى للبرولين 45.65 ppm و زادت فعالية الكاتالاز 0.04 مغ/غ عند المستوى 40 %. و عند المستوى 80 % تميزت معاملة الهيومات 1000ppm بأعلى محتوى للكلوروفيل الكلي في أوراق البطاطا 0.140 مليمول /مغ وأعلى محتوى من البرولين 11.63 ppm. وبالتالي يمكن تطبيق هيومات البوتاسيوم بالتركيز1000 و ppm 1500 لرفع كفاءة تحمل نبات البطاطا صنف سبونتا تحت ظروف نقص الماء.

Glutathione‐induced hydrogen sulfide enhances drought tolerance in sweet pepper (Capsicum annuum L.)

AbstractGlutathione (GSH) has been studied for its potential to enhance stress tolerance in plant systems, but the role of hydrogen sulfide (H2S) in GSH‐induced water stress tolerance in sweet pepper (Capsicum annuum L.) is still under investigation. This study explores how H2S and GSH modulate water stress tolerance in pepper plants, addressing a research gap. The joint effect of sodium hydrosulfide (NaHS), a donor of H2S, and GSH on water stress tolerance was determined through pre‐treatment with the H2S scavenger 0.1 mM hypotaurine (HT). Pepper seedlings were sprayed with 1.0 mM GSH or GSH + 0.2 mM NaHS once a week, with soil moisture content set at 80% and 40% for full irrigation and water stress conditions for a duration of 2 weeks. The results showed that water stress significantly reduced total plant dry weight, chlorophyll a and b content, Fv/Fm, leaf water potential, and relative water content by 50%, 56%, 33%, 27%, 52%, and 34%, while increasing hydrogen peroxide (H2O2), proline, and H2S levels by 152%, 134%, and77%, respectively. Treatment with GSH and NaHS reduced water stress‐induced H2O2 production and improved plant growth, photosynthetic traits, proline, and the activity of L‐cysteine desulfhydrase (L‐DES), leading to the generation of H2S content. GSH reduced NADPH oxidase (NOX), superoxide dismutase (SOD), and H2O2 but increased glutathione peroxidase (GPX) activities. The interaction of NaHS and GSH led to further reductions in NOX, SOD, and H2O2 values but increased GPX activity. The combined GSH and NaHS treatment increased nitric oxide (NO) production but decreased the activity of S‐nitrosoglutathione reductase (GSNOR), potentially accelerating S‐nitrosylation. Hypotaurine negated the positive impacts of GSH on water stress tolerance by reducing H2S concentration in pepper plants, but this was corrected by the concurrent application of NaHS and GSH + HT. Therefore, water stress tolerance requires H2S.

Effect of ethyl methane sulphonate on growth, yield and some physiological parameters of Bambara groundnut (Vigna subterranea (L.) verdc) in non - water stressed and water stressed conditions

Bambara groundnut (Vigna subterranea (L.) Verdc.) is a legume cultivatd majorly for it’s seeds and commonly grown by subsistence farmers in sub-Saharan Africa. In order to determine the effect of ethyl methane sulphonate (EMS) mutagen on the growth, yield and some physiological parameters of non-water stressed (NWS) and water stressed (WS) bambara groundnut. It’s seeds were treated with five concentrations (0.00 (control), 0.25, 0.50, 0.75 and 1.00% v/v) Ethyl methane sulphonate and were grown under two conditions: non-water stressed and water stressed. Analysis of variance (ANOVA) revealed significant differences (P ≤ 0.50) in the emergence percentage (6 DAS), germination percentage (7 DAS), plant height (PH), number of leaves per plant (NL), leaf length (LL), leaf width, (LW), relative water content (RWC), chlorophyll a, b and total chlorophyll contents in the non-water stressed and water stressed plants. After rewatering at 8 WAS, highest number of leaves in NWS and WS conditions were observed in 0.75% EMS concentration (229, 189), highest leaf length in NWS and WS plants were observed in 0.50% EMS concentration (9.47cm, 9.13cm). Highest leaf width in NWS and WS plants was observed in 0.25% EMS concentration (4cm, 3.63cm). Highest number of pods per plant (NP) and weight of pods per plant (WP) were observed in 0.75% EMS concentration only in NWS plants. Highest chlorophyll a, b and total chlorophyll content was observed in 1.00% EMS concentration. The result form this study showed that Ethyl methane sulphonate (EMS) mutagen concentration increased the growth, yield and physiological parameters of Bambara groundnut in non-water stressed condition at different doses, however there was no positive effect of EMS on yield in the water stressed plants.

Melatonin seed priming improves early establishment and water stress tolerance of peanut

Water stress is a major cause of yield loss in peanut cultivation. Melatonin seed priming has been used to enhance stress tolerance in several crops, but not in peanut. We investigated the impact of seed priming with melatonin on the growth, development, and drought tolerance of two peanut cultivars, TUFRunner™ ‘511’, a drought tolerant cultivar, and New Mexico Valencia A, a drought sensitive cultivar. Peanut seed priming tests using variable rates of melatonin (0–200 μM), indicated that 50 μM of melatonin resulted in more uniform seed germination and improved seedling growth in both cultivars under non stress conditions. Seed priming with melatonin also promoted vegetative growth, as evidenced by higher whole-plant transpiration, net CO2 assimilation, and root water uptake under both well-watered and water stress conditions in both cultivars. Higher antioxidant activity and protective osmolyte accumulation, lower reactive oxygen species accumulation and membrane damage were observed in primed compared with non-primed plants. Seed priming with melatonin induced a growth promoting effect that was more evident under well-watered conditions for TUFRunnner™ ‘511’, whereas for New Mexico Valencia A, major differences in physiological responses were observed under water stress conditions. New Mexico Valencia A primed plants exhibited a more sensitized stress response, with faster down-regulation of photosynthesis and transpiration compared with non-primed plants. The results demonstrate that melatonin seed priming has significant potential to improve early establishment and promote growth of peanut under optimal conditions, while also improve stress tolerance during water stress.

Seedling priming with UV-A radiation induces positive responses in tomato and bell pepper plants under water stress

Stimulating crops to cope with various stressful conditions is an increasingly interesting strategy, even more so when this process is done through seed or seedling priming, since it is simpler and cheaper. The use of UV-A radiation for this purpose can be a viable, economical and environmentally friendly alternative. That is why the aim of this study was to evaluate if seedling priming with UV-A radiation is capable to help tomato and bell pepper plants tolerate water stress. For this, an experiment was carried out in both crop plants, where UV-A radiation was applied directly on the seedlings prior to transplanting on a single occasion, and for two hours. The crops were developed both in optimal water conditions and under water stress conditions. The results obtained show that priming with UV-A decreased the negative effects of water stress in tomato, increased fruit yield by 24.5% and root dry biomass by 46% compared to the stressed control. UV-A priming increased the proline content 294% when there was no stress, and 164% under water stress. Moreover, phenolic compounds were increased by UV-A priming under water stress. In bell pepper, priming with UV-A increased root dry biomass 26% compared to stressed control, but there were no differences in fruit yield. UV-A priming increased 68% more MDA when there was no stress, while under water stress increased 34%. In addition, UV-A priming increased chlorophyll content under water stress. Seedling priming with UV-A radiation can be an efficient strategy to induce tolerance to water stress in agricultural crops, with the great advantage that it is an easy-to-apply and environmentally friendly technology.

Drought-induced circular RNAs in maize roots: Separating signal from noise.

Circular RNAs (circRNAs) play an important role in diverse biological processes; however, their origin and functions, especially in plants, remain largely unclear. Here, we used 2 maize (Zea mays) inbred lines, as well as 14 of their derivative recombination inbred lines with different drought sensitivity, to systematically characterize 8,790 circRNAs in maize roots under well-watered (WW) and water-stress (WS) conditions. We found that a diverse set of circRNAs expressed at significantly higher levels under WS. Enhanced expression of circRNAs was associated with longer flanking introns and an enrichment of long interspersed nuclear element retrotransposable elements. The epigenetic marks found at the back-splicing junctions of circRNA-producing genes were markedly different from canonical splicing, characterized by increased levels of H3K36me3/H3K4me1, as well as decreased levels of H3K9Ac/H3K27Ac. We found that genes expressing circRNAs are subject to relaxed selection. The significant enrichment of trait-associated sites along their genic regions suggested that genes giving rise to circRNAs were associated with plant survival rate under drought stress, implying that circRNAs play roles in plant drought responses. Furthermore, we found that overexpression of circMED16, one of the drought-responsive circRNAs, enhances drought tolerance in Arabidopsis (Arabidopsis thaliana). Our results provide a framework for understanding the intricate interplay of epigenetic modifications and how they contribute to the fine-tuning of circRNA expression under drought stress.