Effects Of Drought Stress Research Articles

Approaches for the amelioration of adverse effects of drought stress on soybean plants: from physiological responses to agronomical, molecular, and cutting-edge technologies

Approaches for the amelioration of adverse effects of drought stress on soybean plants: from physiological responses to agronomical, molecular, and cutting-edge technologies

Utilizing physiologies, transcriptomics, and metabolomics to unravel key genes and metabolites of Salvia miltiorrhiza Bge. seedlings in response to drought stress

Drought stress inhibits Salvia miltiorrhiza Bunge (S. miltiorrhiza) seedling growth and yield. Here, we studied the effects of drought stress on the different parts of S. miltiorrhiza seedlings through physiological, transcriptomic, and metabolomics analyses, and identified key genes and metabolites related to drought tolerance. Physiological analysis showed that drought stress increased the accumulation of hydrogen peroxide (H2O2), enhanced the activity of peroxidase (POD), decreased the activity of catalase (CAT) and the contents of chlorophyll b and total chlorophyll, reduced the degree of photosynthesis, enhanced oxidative damage in S. miltiorrhiza seedlings, and inhibited the growth of S. miltiorrhiza plants. Transcriptome analyses revealed 383 genes encoding transcription factors and 80 genes encoding plant hormones as hypothetical regulators of drought resistance in S. miltiorrhiza plants. Moreover, differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) are involved in a variety of biological processes, such as proline and glycine betaine metabolism, and biosynthesis of tanshinones and phenolic acids. Additionally, it has barely been reported that the AHL gene family may be involved in regulating the neocryptotanshinone biosynthesis. In conclusion, our results suggest that drought stress inhibits S. miltiorrhiza seedling growth by enhancing membrane lipid peroxidation, attenuating the antioxidant system, photosynthesis, and regulating proline and glycine betaine metabolism, transcription factors and plant hormones, and tanshinones and phenolic acid metabolism pathways. This study provides new insights into the complex mechanisms by which S. miltiorrhiza responds to drought stress.

Effect of crude extract and polysaccharides derived from Fucus spiralis on radish plants Raphanus sativus L. agrophysiological traits under drought stress

Drought is a significant environmental stressor that induces changes in the physiological, morphological, biochemical, and molecular traits of plants, ultimately resulting in reduced plant growth and crop productivity. Seaweed extracts are thought to be effective in mitigating the effects of drought stress on plants. In this study, we investigated the impact of crude extract (CE), and polysaccharides (PS) derived from the brown macroalgae Fucus spiralis (Heterokontophyta, Phaeophyceae) applied at 5% (v/v) and 0.1% (w/v) respectively on radish plants Raphanus sativus L. subjected to varying levels of drought stress, specifically 80% of field capacity (FC) for no stress, 60% FC for moderate stress, and 40% FC for severe stress. Our examination of growth parameters, along with physiological and biochemical characteristics, revealed that both CE and PS increased the fresh weight over the control by 47.43% and 64% at 40% FC and 12.5% and 38% at 60% FC respectively. Under stress (40% FC), the application of CE and PS decreased proline content of radish leaves by 23.45% and 6.46% respectively in comparison with the control. Furthermore, PS treatment caused an increase of the alkaline phosphatase and urease activity in the soil by 182.5% and 34.6% respectively. CE and PS treatments led to decreased sugar content and total phenolics levels. Notably, lipid peroxidation was reduced in stressed plants treated with both CE and PS, with PS treatment yielding lower concentrations (3.75 nmol MDA.g− 1 FW at 40% FC). Overall, F. spiralis extracts interacted through several mechanisms using various compounds to mitigate the negative effects of drought stress on radish plants. These results demonstrate that seaweed extracts could be adopted in integrated production systems to boost food productivity under harsh climatic conditions.

Manipulating stomatal aperture by silencing StSLAC1 affects potato plant-herbivore-parasitoid tritrophic interactions under drought stress.

The effects of drought stress on stomatal opening dynamics, plant volatile organic compound (VOC) emissions and plant-insect interactions have been well-documented individually, but how they interact mechanistically remains poorly studied. Here, we studied how drought-triggered stomatal closure affects VOC emission and plant-trophic interactions by combining RNAi silencing, molecular biological and chemical analyses (GC-MS) of a potato-tuber moth-egg parasitoid tritrophic system. Drought stress attenuated stomatal apertures and VOC emissions, which made the potato (Solanum tuberosum L.) plants more attractive to the herbivore but less attractive to the parasitoid. Stomatal aperture manipulations through StSLAC1 gene knockdown and chemicaltreatments (ABA and 5-aminolevulinic acid) consistently affected drought-triggered VOC emissions and plant-herbivore-parasitoid interactions, supporting aperture-dependent VOC emission. RNA-Seq analysis revealed that drought stress did not transcriptionally inhibitVOC biosynthesis. Collectively, our findings are consistent with the stomatal regulation of plant-insect interactions through the modulation of VOC emissions under drought stress. This highlights the intricate interplay between stomatal dynamics, VOC emission and plant-insect interactions.

Impact of arbuscular mycorrhizal fungi on maize rhizosphere microbiome stability under moderate drought conditions.

With an alarming increase in global greenhouse gas emissions, unstable weather conditions are significantly impacting agricultural production. Drought stress is one of the frequent consequences of climate change that affects crop growth and yield. Addressing this issue is critical to ensure stable crop productivity under drought conditions. Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with plants and enhance their resistance to adverse conditions. Effects of arbuscular mycorrhizal associations on the rhizosphere microbiome and root transcriptome under drought conditions have not been explored. Here, we investigated the effects of AMF and drought stress on rhizosphere microorganisms and root transcriptome of maize plants grown in chernozem soil. We used high-throughput sequencing data of bacterial 16S rRNA and fungal internal transcribed spacer regions (ITS) to identify rhizosphere microorganisms. Transcriptomic data were used to assess gene expression in maize plants under different treatments. Our results show that AMF maintains the composition of maize rhizosphere microorganisms under drought stress. In particular, the bacterial and fungal phyla maintained were Actinomycetes and Ascomycota, respectively. Transcriptomic data indicated that AMF influenced gene expression in maize plants under drought stress. Under drought stress, the expression of SWEET13, CHIT3, and RPL23A was significantly higher in the presence of AMF than it was without AMF inoculation, indicating better sugar transport, reduced malondialdehyde accumulation, and improved water use efficiency in AMF-inoculated maize plants. These findings suggest that AMF can enhance the resistance of maize to moderate drought stress by stabilising plant physical traits, which may help maintain the structure of the rhizosphere microbial community. This study provides valuable theoretical insights that should aid the utilization of AMF in sustainable agricultural practices.

Effect of Heat and Drought Stress on the Growth of Selected Grass Species of Pothohar Region

Effect of Heat and Drought Stress on the Growth of Selected Grass Species of Pothohar Region

Assessing the effects of drought stress on photosynthetic performance and physiological resistance in camphor seedling leaves.

The impact of seasonal short-term drought on plant physiology and resilience is crucial for conservation and management strategies. This study investigated drought stress effects on growth, photosynthetic capacity, and physiological responses of Camphor (Cinnamomum camphora) seedlings in Guangxi province, China. Fertilized potted plants underwent continuous drought treatments to assess varying water supply effects. Treatments included normal water supply (CK), light drought (D1), moderate drought (D2), and severe drought (D3). Physiological indicators including net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and intercellular CO2 concentration (Ci) were measured. Additionally, the stomatal limitation value (Ls) was calculated using the formula Ls = 1-Ci/Ca, and water use efficiency (WUE) was computed as Pn/Tr. Furthermore, parameters such as PIABS (Performance Index based on absorbed light energy), WK (the ratio of variable fluorescence FK at the K point to the amplitude FO-FJ), VJ (the ratio of variable fluorescence FJ at the J point to the amplitude FO-FP), ΔI/I0 (the relative amplitude of the 820 nm light absorption curve), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) were measured to evaluate the impact of drought stress on various physiological processes and antioxidant enzyme activities. Results showed significant decreases in base diameter growth (GD) and seedling height growth (GH) with increasing drought stress. Notably, moderate (D2) and severe (D3) drought treatments led to negative GD values. GD decreased by 23.79%, 114.85%, and 175.50% for D1, D2, and D3 treatments, respectively, while reductions of 40.00%, 73.33%, and 90.00% in GD were observed compared to the control (CK). Pn decreased significantly across treatments, with D1<CK<D2<D3 in Ci. Stomatal limit value (Ls) and water use efficiency (WUE) followed the order: D1>CK>D2>D3. Light energy transmission to PSI by the unit reaction center (REo/RC) initially increased then decreased, significantly smaller in D3 compared to D1. Conversely, heat dissipation absorbed by the unit reaction center (DIo/RC) increased notably in D3 compared to D1 and CK. PIABS, WK, VJ, and ΔI/I0 decreased over time, while Rubisco enzyme activity decreased, while proline (Pro) levels increased. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) levels significantly increased during D1 treatment but decreased with D2 and D3 treatments. Overall, drought severity had varying impacts on Cinnamomum camphora growth and photosynthetic structure, with D1 treatment maintaining normal growth and metabolic activities, while D2 and D3 treatments resulted in severe membrane damage, rendering seedlings essentially unable to survive. These findings provide a theoretical basis for implementing water management practices and conservation strategies for camphor seedlings.

Mitigating the adverse effects of drought stress on sunflower plants via foliar application of salicylic acid

Sunflower is the primary oilseed crop of Pakistan, valued for its edible oil and high yield potential under favorable conditions. However, drought stress is a major limiting factor affecting sunflower productivity, causing significant yield reductions. The present study aimed to evaluate the potential role of salicylic acid in enhancing the growth and physiological performance of sunflowers under drought stress. Drought stress was applied 20 days after sowing, with three experimental treatments conducted in five replications: (a) control (normal conditions), (b) drought stress, and (c) drought stress supplemented with 250 mg L? salicylic acid. Key findings revealed that the foliar application of 250 mg L? salicylic acid significantly improved various growth parameters, including shoot length (24.92%), root length (18.97%), fresh shoot weight (15.78%), dry shoot weight (24.15%), fresh root weight (21.32%), and dry root weight (26.72%). Moreover, chlorophyll content increased by 32.90%, stomatal conductance by 19.52%, relative water content by 20.84%, and membrane stability index by 41.79%. Moreover, salicylic acid markedly mitigated oxidative damage, reducing malondialdehyde levels by 32.81% and hydrogen peroxide levels by 17.80% compared to untreated plants. Furthermore, the treatment enhanced the activity of antioxidant enzymes, with superoxide dismutase activity increasing by 17.25%, catalase by 40.05%, and peroxidase by 10.41%. In conclusion, the foliar application of 250 mg L? salicylic acid effectively enhances the growth and physiological parameters of sunflower under drought stress, offering a sustainable and reliable strategy to mitigate the adverse effects of water scarcity on crop production.

Morphophysiological Response of Peranggi Chili (Capsicum annum L. var chinensis) to Drought Stress

Peranggi chili (Capsicum annum L. var chinensis) is a red chili that has a spicy taste. Peranggi chili is not widely known by the community and has not been widely studied. In addition, peranggi chili is very easily exposed to drought so its growth is easily disrupted. This study aimed to determine morphophysiology of peranggi chili with PEG treatment as drought stress with concentrations of 0%, 10%, 20%, and 30%. This research was conducted from June to November 2024. The study used an experimental method with a completely randomized design (CRD) to test the growth of peranggi chili with PEG 6000 treatment as drought stress with concentrations of 0%, 10%, 20%, and 30%. The treatment was given after the chili grew 30 days after transfer (DAT). Measurements were taken at 40, 50, 60, and 70 DAT. The results showed that the morphology of peranggi chili plants was not affected by different concentrations of PEG 6000 except root length which decreased significantly at 70 DAT. The shoot: root fresh and dry weight ratio decreased until 50 DAT and reduce slowly until 70 DAT. Similarly, physiological measurements in the form of chlorophyll a, b, and total content decreased from 50 to 70 DAT, but the treatment level had a different impact. From this study, the effect of drought stress using PEG 6000 0%, 10%, 20%, and 30% began to affect the vegetative growth of peranggi chili peppers at 50 DAT.

Impact of Irrigation Cessation on Physiological, Photosynthetic, and Enzymatic Activities in Wheat (Triticum aestivum L.) at Varying Plant Densities

Drought stress is one of the most critical factors reducing the performance of crop plants in arid and semi-arid regions globally, highlighting the importance of understanding underlying mechanisms to combat such stress. Therefore, this experiment aimed to investigate the effect of drought stress and planting density on the physiological characteristics, photosynthetic pigments, and enzymatic activity of wheat plants. The experiment was conducted in a factorial arrangement based on a completely randomized block design with three replications. The treatments included irrigation cessation at three levels (control, irrigation until flowering (IUF), and irrigation until the roughing (IUD)), and plant density (300, 400, 500, and 600 plants m-2). The results indicated that leaf relative water content, soluble sugars, cell membrane stability index, chlorophyll a, b, and carotenoids were significantly decreased at IUF treatment, while these parameters increased at higher plant densities. Additionally, the interaction of drought stress and plant density significantly affected leaf proline and flavonoid content, total chlorophyll, and catalase activity. The highest leaf proline content (3.88 mg g-1 FW) was observed in the treatment with IUF and a density of 600 plants m-2, representing a 192% increase compared to the control. Additionally, the highest total chlorophyll content (3.66 mg g-1 FW) was recorded at no-stress conditions with a density of 500 plants m-2. Under drought stress conditions, the activity of antioxidant enzymes also increased. Overall, our results indicate that a density of 500 plants m-2 is optimal for maintaining stable growth conditions in wheat. These findings provide valuable insights for policymakers to develop effective agronomic strategies to mitigate drought stress, particularly in arid and semi-arid regions.

The effect of silicon supplementation and drought stress on the deposition of callose and chemical components in the cell walls of the Brassica napus roots.

Silicon has an important role in regulating water management in plants. It is deposited in cell walls and creates a mechanical barrier against external factors. The aim of this study was to determine the role of silicon supplementation in the synthesis and distribution of callose in oilseed rape roots and to characterize the modifications of cell wall structure of these organs after exposure to drought stress. Histological and ultrastructural analyses were performed to determine the changes in the distribution of arabinogalactan proteins, pectins, and extensin in roots of Brassica napus growing under drought and supplemented with silicon. Callose deposition and the accumulation of callose synthase protein were assessed, followed by transcriptional analysis of callose synthase genes. The results showed that silicon supplementation under drought conditions alter the direction of cortex cell differentiation, promoting fiber formation and proliferation of callose-depositing cells in the roots of the tested plants. This was reflected in an increase in the level of callose synthase and a decrease in the transcriptional activity of the gene encoding this enzyme, indicating regulation based on negative feedback under drought stress. The changes in abundance and distribution of investigated arabinogalactan proteins, pectins and extensin in roots of Si supplemented plants growing under drought stress were observed, indicating cell walls remodeling. Silicon supplementation in oilseed rape roots induced significant changes in cell wall composition, including increased callose deposition and altered pectins and arabinogalactan proteins distribution. These modifications, along with the formation of fibres in the root cortex, likely contribute to enhanced cell wall strength providing a physical barrier against water loss and mechanical stress, as a probable defence mechanism induced during drought stress.

Foliar application of nano-silicon enhances drought tolerance rate of pot marigold (Calendula officinalis L.) by regulation of abscisic acid signaling

Pot marigold (Calendula officinalis L.) is an herbaceous ornamental and medicinal plant. Climate models predict a reduction of precipitations and increasing the average temperature. Therefore, agricultural plants will be more frequently exposed to water deficit stress. To investigate the influence of nano-silicon foliar application (0, 50, 100, and 200 mg L− 1) on the alleviation of drought stress (100, 75, and 50% Field capacity (FC)) adverse effects on marigold plant characteristics, a factorial experiment was conducted based on a completely randomized design with three replications. The chlorophyll content of plants treated with nano-silicon 200 mg L− 1 decreased by 8.39% when drought stress increased from 100 to 50% FC. In line with electrolyte leakage percentage, the highest malondialdehyde and H2O2 content was measured in non-treated plants under a drought level of 50% FC. The activity of peroxidase and superoxide dismutase enzymes increased with increasing nano-silicon concentration and drought stress severity. Under all levels of nano-silicon treatment, the cell’s abscisic acid content increased with increasing drought severity. Also, the highest abscisic acid content was measured in plants treated with nano-silicon 100 and 200 mg L− 1. There was a significant negative correlation between electrolyte leakage, malondialdehyde and H2O2 content, and morphological characteristics, photosynthetic pigments content, total protein, and antioxidant enzymes activity. The positive effect of nano-silicon application is correlated with enhancing antioxidant enzymes activity, membrane stability, and cell osmotic potential. Also, one of the most critical mechanisms of silicon’s effect on the alleviation of stress damage is the regulation of abscisic acid signaling. As a result, foliar application of nano-silicon could be introduced as a promising and influential technique to overcome the adverse effects of drought stress on morpho-physiological and biochemical characteristics of the marigold plant.

Synergistic Effect of Iron and Zinc Nanoparticles with Recommended Nitrogen Dose on Production and Grain Quality of Maize (Zea mays L.) Cultivars Under Drought Stress

Abiotic factors, such as drought, can significantly impact the vegetative growth and productivity of maize. To investigate the effects of the combined foliar application of zinc (Zn) and iron (Fe) nanoparticles with the recommended nitrogen dose (RND) on maize production and grain chemical composition under different water regimes, two field experiments were conducted in El-Ayyat city, Giza, Egypt, during the summer seasons of 2022 and 2023. This study utilized a split-split-plot experimental design with three replications. The main plots were designated to different water regimes (100, 80, 60, and 40% of estimated evapotranspiration), while the sub-plots were randomly distributed with Zn and Fe nanoparticle concentrations (0, 100, and 200 mg/L). The sub-sub-plots were randomly allocated to three maize cultivars (SC-P3062, SC-32D99, and SC-P3433). The results revealed that exposure to drought conditions resulted in a significant decline in the yield and yield-related attributes across all maize cultivars examined. Grain yield decreased by 10–50% under drought conditions. However, the foliar application of Zn and Fe nanoparticles was found to significantly improve grain yield, protein content, oil content, starch content, crude fiber, ash, and macro- and micronutrient concentrations in the maize cultivars under control and drought stress conditions. The foliar application of Zn and Fe nanoparticles at a concentration of 200 mg/L to the SC-P3433 maize cultivar led to the greatest grain yield per hectare, reaching 11,749 and 11,657 kg under the irrigation regimes with 100 and 80% total evapotranspiration, respectively. According to the assessment using the relative drought index, the SC-P3062 maize cultivar demonstrated tolerance (T) to water stress conditions. In conclusion, the foliar application of Zn and Fe nanoparticles (100–200 mg/L) effectively mitigated the negative effects of drought stress on maize plants. This approach can be recommended for farmers in arid and semi-arid regions to maintain and improve maize yield and grain quality under water-deficit conditions.

Vicia faba overcomes drought stress by spraying with Xerophytic Anabasis setifera extract

Drought stress is a prevalent environmental factor significantly impacting the faba bean (Vicia faba L.) crop. Anabasis setifera, a plant extract (ASE), has been found to potentially regulate plant responses to drought stress for the first time. The study examined the effects of applying an exogenous ASE on the physiological, biochemical, and yield responses of faba bean plants under three soil water regimes: well-watered (8-day irrigation intervals), moderate drought stress (12-day irrigation intervals), and severe drought stress (16-day irrigation intervals). The HPLC analysis of ASE revealed that it contains major phenolic compounds such as rutin, chlorogenic acid, gallic acid, ferulic acid, and coumaric acid. The extract also contains catechin, quercetin, syringic acid, pyro catechol, and methyl gallate. The study found that faba bean plants showed enhanced drought resistance after treatment with ASE. This treatment improved growth parameters like shoot and root length, fresh and dry weight, leaf and flower number, and reduced the negative impacts of drought stress on chlorophyll levels and metabolic activities. The study indicates that plants treated with ASE, including catalase, peroxidase, and polyphenol oxidase, can significantly mitigate drought stress effects, improve yield trials, and enhance seed components, making it cost-effective and ecologically beneficial.

Effect of Drought Stress and Short-term Recovery on Proline and Polyamine Metabolism in Lotus japonicus

Effect of Drought Stress and Short-term Recovery on Proline and Polyamine Metabolism in Lotus japonicus

Effects of drought and salt stress on the root phenotype of wheat seedlings and underlying gene expression analysis.

In our previous study, three TaPSK genes highly expressed in the roots of wheat were screened. To explore the effects of adverse stresses on the wheat root phenotype and the expression of TaPSK3, TaPSK9 and TaPSK10, we measured the phenotypic parameters of the JM22 root system at the seedling stage after treatment with different concentrations of NaCl and PEG6000. Additionally, the relative expression levels of TaPSK3, TaPSK9, and TaPSK10 were analyzed via RT-qPCR within 72 h of treatment with 150 mM NaCl and 30% PEG6000. The results revealed that drought and salt stress significantly inhibited phenotypic parameters such as total root length, root surface area, root biomass distribution estimation and root tip number in wheat. Notably, salt stress causes wheat roots to germinate more root hairs. The expression of TaPSK3 did not change significantly during salt stress but was upregulated approximately five-fold at 12 h of drought stress. The gene expression levels of TaPSK9 and TaPSK10 were upregulated to varying degrees but gradually returned to normal at 72 h. These results show that when wheat encounters stresses, the expression of TaPSK genes is upregulated to promote root growth and ensure the normal growth and development of plants. This study provides data and theoretical support for further study of TaPSK gene function and cultivation of high-quality wheat plants with strong stress resistance.

INFLUENCE OF THE TIMING OF THE APPLICATION OF SALICYLIC ACID ON THE QUANTITATIVE YIELD AND SOME BIOCHEMICAL CHARACTERISTICS OF BARLEY (Hordeum vulgare L.) UNDER DEFICIT IRRIGATION

Using salicylic acid (SA) to feed drought-stressed plants plays a vital role in reducing the adverse effects of water stress and improving plant performance. This study explores the role of salicylic acid and different barley cultivars in mitigating the effects of drought stress on barley.The study examined three irrigation levels—one-time irrigation (severe stress), two-time irrigation (moderate stress), and four-time irrigation (control)—along with foliar and non-foliar applications of salicylic acid (SA) at three key stages of the Zadoks Growth Scale (ZGS): ZGS 29 (end of tillering), ZGS 34 (50% stem elongation), and ZGS 39 (completion of flag leaf emergence). These treatments were applied to three barley cultivars—Khatam, Reyhan, and Nosrat— which are considered semi-tolerant to drought stress. The findings showed that the interaction of reduced irrigation and SA increased chlora (8.8%) and b (7.12%) in the ZGS34 treatment under control conditions compared to the treatment without SA. The proline content increased with increasing drought stress, with the highest proline content obtained at the end of the tillering stage in the control condition. Compared to the control, which had no foliar spraying, the specific leaf area increased by 3.8, 1.8, and 0.4%, respectively. Relative water content in Khatam (35.6%), Reyhan (33.3%) and Nosrat (30.5%) decreased with increasing stress in the control treatment compared to the minimum stress. The most sensitive cultivar to lack of irrigation was Khatam. The rate of yield increase by SA compared to the control was (10.33%) among the barley cultivars cultivated, the cultivar Reyhan had a comparative advantage in more measures, mainly when applied at ZGS29. In conclusion, SA improved the drought tolerance of the barley and increased the yield by improving the biochemical characteristics.

Effects of Drought Stress at the Booting Stage on Leaf Physiological Characteristics and Yield of Rice.

Drought stress is a major environmental constraint that limits rice (Oryza sativa L.) production worldwide. In this study, we investigated the effects of drought stress at the booting stage on rice leaf physiological characteristics and yield. The results showed that drought stress would lead to a significant decrease in chlorophyll content and photosynthesis in rice leaves, which would affect rice yield. Three different rice varieties were used in this study, namely Hanyou73 (HY73), Huanghuazhan (HHZ), and IRAT109. Under drought stress, the chlorophyll content of all cultivars decreased significantly: 11.1% and 32.2% decreases in chlorophyll a and chlorophyll b in HHZ cultivars, 14.1% and 28.5% decreases in IRAT109 cultivars, and 22.9% and 18.6% decreases in HY73 cultivars, respectively. In addition, drought stress also led to a significant decrease in leaf water potential, a significant increase in antioxidant enzyme activity, and an increase in malondialdehyde (MDA) content, suggesting that rice activated a defense mechanism to cope with drought-induced oxidative stress. This study also found that drought stress significantly reduced the net photosynthetic rate and stomatal conductance of rice, which, in turn, affected the yield of rice. Under drought stress, the yield of the HHZ cultivars decreased most significantly, reaching 30.2%, while the yields of IRAT109 and HY73 cultivars decreased by 13.0% and 18.2%, respectively. The analysis of yield composition showed that the number of grains per panicle, seed-setting rate, and 1000-grain weight were the key factors affecting yield formation. A correlation analysis showed that there was a significant positive correlation between yield and net photosynthetic rate, stomatal conductance, chla/chlb ratio, Rubisco activity, and Fv/Fm, but there was a negative correlation with MDA and non-photochemical quenching (NPQ). In summary, the effects of drought stress on rice yield are multifaceted, involving changes in multiple agronomic traits. The results highlight the importance of selecting and nurturing rice varieties with a high drought tolerance, which should have efficient antioxidant systems and high photosynthetic efficiency. Future research should focus on the genetic mechanisms of these physiological responses in order to develop molecular markers to assist in the breeding of drought-tolerant rice varieties.

Enhancing maize drought and heat tolerance: single vs combined plant growth promoting rhizobacterial inoculation

Maize (Zea mays L.), a key staple crop in Sub-Saharan Africa, is particularly vulnerable to concurrent drought and heat stress, which threatens crop yield and food security. Plant growth-promoting rhizobacteria (PGPR) have shown potential as biofertilizers to enhance plant resilience under such abiotic stresses. This study aimed to (1) identify PGPR isolates tolerant to drought and heat, (2) assess their capacity to mitigate the effects of these stresses on early maize growth, and (3) analyze maize gene expression changes associated with PGPR-induced tolerance. Rhizobacteria were isolated and screened for drought and heat tolerance, alongside key plant growth-promoting (PGP) traits, including phosphorus solubilization, nitrogen fixation, and indole acetic acid production. In vitro and pot trials evaluated the effects of selected isolates on maize growth under stress, using indicators such as shoot length, root and shoot biomass (wet and dry), and leaf water content. Quantitative reverse transcription PCR (qRT-PCR) was employed to profile maize stress response genes. The identified PGPR isolates included Bacillus cereus (11MN1), Bacillus pseudomycoides (21MN1B), Lelliottia amnigena (33MP1), and Leclercia adecarboxylata (36MP8). Greenhouse trials demonstrated that L. amnigena 33MP1, L. adecarboxylata 36MP8, and a mixed culture of isolates (11MN1, 21MN1B, 33MP1, 36MP8) effectively alleviated the adverse effects of concurrent drought and heat stress in maize. Notably, qRT-PCR analysis indicated that PGPR-induced tolerance may involve the modulation of stress response genes CAT2 (catalase 2) and DHN2 (dehydrin 2), which play roles in oxidative stress management and cellular protection. The PGPR isolates identified in this study represent promising bioinoculants for enhancing maize resilience under climate-induced stresses, offering a sustainable approach to improve maize productivity, conserve water, and reduce irrigation needs in drought-prone regions.

Impact of Salicylic Acid and Potassium Silicate in Ameliorating the Drought Stress Effect on Sorghum (Sorghum bicolor L. Moench)

Aims: The present study highlights the impact of salicylic acid and potassium silicate in reducing the deleterious effect of drought stress on sorghum. Study Design: Split plot design. Place and Duration of Study: Agricultural College Farm, Bapatla, Andhra Pradesh during rabi, 2023-24. Methodology: The experiment consist of two main treatments i.e., water stress treatments viz., M1 (stress treatment i.e., moisture stress was imposed from vegetative to flowering (25-70 DAS) and M2 (No stress treatment) and eight sub treatments viz., No spray (S1), K-Silicate @50ppm at 35+45 DAS (S2), K-Silicate @100ppm at 35+45 DAS (S3), SA @150ppm at 35+45 DAS (S4), SA @200ppm at 35+45 DAS (S5), K-Silicate @50ppm + SA @200ppm at 35+45 DAS (S6), K-Silicate @100ppm + SA @200ppm at 35+45 DAS (S7) and K-Silicate @150ppm + SA @200ppm at 35+45 DAS (S8) replicated thrice. The plant samples were collected on 30, 50 and 70 DAS. Results: The sorghum plants under water stress showed drastic reductions in chlorophyll content (54.9%), relative water content (34.1%) and increase in membrane injury index (1.9 folds), proline content (1.8 folds) and catalase activity (3.6 folds). The combined spray of potassium silicate @100ppm + SA @200ppm exhibited superior performance by enhancing the chlorophyll content by 59.1%, relative water content by 32.5, proline content by 26.1%, catalase activity by 30.4% and reducing membrane injury index by 28.9%. Conclusion: It can be concluded that the foliar application of @100ppm + SA @200ppm at 35 + 45 DAS helped the sorghum plants from the negative effects of water stress from vegetative to flowering stages.