Presence Of Drought Stress Research Articles

Comparative study on physiological intricacies and sugar accumulation dynamics in brinjal (Solanum melongena L.) under drought stress

Drought stress is a major abiotic factor affecting the growth and productivity of brinjal (Solanum melongena L.). In this study, we evaluated the effect of drought stress on morphological, physiological and metabolomic response in susceptible genotypes Solanum melongena var. insanum, CO-2 and tolerant genotype Arka Harshitha at three timepoints.The results showed that drought stress significantly reduced the shoot length, root length, biomass, leaf area, photosynthetic rate and intrinsic water use efficiency in susceptible genotypes, while the tolerant genotype Arka Harshitha maintained comparatively higher growth rates, leaf area, photosynthetic rate and water use efficiency. Further, Arka Harshitha exhibited lower lipid peroxidation and higher antioxidant enzyme activity at all the time interval compared to the susceptible genotypes. Additionally, genotype specific sugar accumulation patterns were observed in root and leaf sugars under control and drought conditions. In the presence of drought stress, the tolerant genotype Arka Harshitha exhibited elevated concentrations of glucose, fructose, sucrose, mannose, inositol, and fucose. Conversely, the susceptible genotype Solanum melongena var. insanum accumulated xylose, arabinose, mannose, fructose, glucose, and sucrose sugars. Higher content of these sugars may positively regulate energy metabolism, osmotic adjustment, and signaling under drought conferring response to drought stress. The results from principal component analysis indicate that fructose, glucose, ribose, xylose, sucrose, sorbitol, arabinose, mannose, ribose, and fucose are expected to play a positive and significant role in the drought tolerance of brinjal. These findings provide an initial insight on importance of differential responses in sugar accumulation under drought stress.

Water stress effect on durum wheat (Triticum durum Desf.) advanced lines at flowering stage under controlled conditions

Drought stress is a key factor affecting Morocco's agricultural productivity. In order to adapt to climate change, it is crucial to select new genotypes which may be slightly but not significantly less efficient. Durum wheat (Triticum durum Desf.) is one of the most important and cereal crops that are impacted by drought. The objective of this research was to assess the performance of 16 durum wheat genotypes to drought stress. From the beginning of flowering stage until the beginning of seed maturity, three levels of water treatment were applied, corresponding to 100%, 66% and 33% of field capacity. Three agro-morphological, five physiological and three biochemical traits were investigated in those genotypes grown under controlled greenhouse conditions over two years (2020 and 2021), by following completely randomized design (CRD) with three replications. The results showed that stomatal conductance, relative water content, leaf area, leaf temperature, SPAD values, proline, soluble sugars, glycine betaine and yield traits were significantly (p < 0.05) affected by the water treatment. In all the genotypes, three advanced lines had the highest seed yield, namely, DYT1TAZI (12.75 g) with a 16.2% decrease from the control, DYT11TAZI (12.74 g, down 17.5%) and DYT5TAZI (12.26 g, down 19.24%), were found to be the most drought-tolerant, stable and productive having exhibited their highest performance in the absence and presence of drought stress. They had the best seed yield per plant (>12 g; p < 0.001) associated with the highest relative water content RWC (>50%; p < 0.001), chlorophyll content (>50 SPAD; p < 0.001), proline content (400μg/100 mg MF; P < 0.001), soluble sugars content (500μg/100 mg MF; P < 0.001), and stomatal conductance (>0.6 mol m-2s-1; p < 0.001). Therefore, these lines could be selected as relevant and valuable germplasms to be used in durum wheat breeding programs aiming to develop drought-tolerant and high-yielding varieties. High relative water content and stomatal conductance along with low leaf temperature can be taken as selection indices in this breeding program.

Serpentine endophytic bacterium Pseudomonas azotoformans ASS1 accelerates phytoremediation of soil metals under drought stress

This study evaluates the potential of serpentine endophytic bacterium to foster phytoremediation efficiency of Trifolium arvense grown on multi-metal (Cu, Zn and Ni) contaminated soils under drought stress. A drought resistant endophytic bacterial strain ASS1 isolated from the leaves of Alyssum serpyllifolium grown in serpentine soils was identified as Pseudomonas azotoformans based on biochemical tests and partial 16S rRNA gene sequencing. P. azotoformans ASS1 possessed abiotic stress resistance (heavy metals, drought, salinity, antibiotics and extreme temperature) and plant growth promoting (PGP) properties (phosphate solubilization, nitrogen fixation, production of 1-aminocyclopropane-1-carboxylate deaminase, siderophore and ammonia). Inoculation of T. arvense with ASS1 considerably increased the plant biomass and leaf relative water content in both roll towel assay and pot experiments in the absence and presence of drought stress (DS). In the pot experiments, ASS1 greatly enhanced chlorophyll content, catalase, peroxidase, superoxide dismutase activities, and proline content (only in the absence of drought) in plant leaves, whereas they decreased the concentrations of malondialdehyde. Irrespective of water stress, ASS1 significantly improved accumulation, total removal, bio-concentration factor and biological accumulation coefficient of metals (Cu, Zn and Ni), while decreased translocation factors of Cu. The effective colonization and survival in the rhizosphere and tissue interior assured improved plant growth and successful metal phytoremediation under DS. These results demonstrate the potential of serpentine endophytic bacterium ASS1 for protecting plants against abiotic stresses and helping plants to thrive in semiarid ecosystems and accelerate phytoremediation process in metal polluted soils.

Seed inoculation with Azospirillum lipoferum alleviates the adverse effects of drought stress on wheat plants

Drought is one of the major environmental stresses that adversely affects crop growth and productivity worldwide. The effect of inoculation with Azospirillum lipoferum on growth, yield, water status, osmoprotectant, antioxidant system and grain anatomy of wheat plants under drought stress conditions was investigated. The plants exposed to the drought stress exhibited a significant reduction in growth, grains yield, relative water content and leaf photosynthetic pigments, as well as alterations in grain anatomy. However, the treatment with A. lipoferum alleviated the stress generated by drought and improved the above-mentioned parameters. Drought stress increased proline, protein, soluble carbohydrates, relative membrane permeability and activities of antioxidant enzymes (SOD and POX). The antioxidant enzymes, phenols and grain anatomy exhibited changes in response to A. lipoferum inoculation in the absence or presence of drought stress. Our data suggest that inoculation with A. lipoferum could protect wheat plants from the harmful effects of drought stress through changes in the antioxidant defense system.

The H2-oxidizing Rhizobacteria Associated with Field-Grown Lentil Promote the Growth of Lentil Inoculated with Hup+ Rhizobium Through Multiple Modes of Action

Certain H2-oxidizing rhizobacteria promote the growth of legume plants nodulated with rhizobia devoid of an uptake hydrogenase system (Hup−). We demonstrated and assessed the plant growth-promoting ability of H2-oxidizing rhizobacteria naturally associating with lentil roots nodulated by rhizobia possessing an uptake hydrogenase system (Hup+ lentil) in semiarid Canada. The ten H2-oxidizing rhizobacteria isolated were strains of Variovorax paradoxus, Variovorax sp., Rhodococcus sp., Mycobacterium sp., Acinetobacter sp., Acinetobacter calcoaceticus, and Curtobacterium sp. Several of these strains increased Hup+ lentil shoot and root biomasses, and root nodule number in the absence or presence of drought stress. Inoculation with H2-oxidizing rhizobacteria enhanced the growth of Hup+ lentil infected by the fungal root pathogens Fusarium avenaceum, Rhizoctonia solani, and Pythium ultimum. Fusarium avenaceum growth was markedly suppressed by all H2-oxidizing rhizobacteria in vitro, and seven isolates also suppressed the growth of both R. solani and P. ultimum. Siderophore production was detected in nine isolates and one isolate could solubilize phosphate. Indole-3-acetic acid production was found in four isolates, and 1-aminocyclopropane-1-carboxylate deaminase activity in six isolates. Most H2-oxidizing rhizobacterial isolates exhibited multiple plant growth-promoting attributes and all isolates exhibited at least one. Our results suggest that the H2-oxidizing rhizobacteria naturally associating with lentil roots in semiarid Canada are beneficial in an Hup+ environment.

Drought-Tolerant Corn Hybrids Yield More in Drought-Stressed Environments with No Penalty in Non-stressed Environments.

The potential benefit of drought-tolerant (DT) corn (Zea mays L.) hybrids may depend on drought intensity, duration, crop growth stage (timing), and the array of drought tolerance mechanisms present in selected hybrids. We hypothesized that corn hybrids containing DT traits would produce more consistent yields compared to non-DT hybrids in the presence of drought stress. The objective of this study was to define types of production environments where DT hybrids have a yield advantage compared to non-DT hybrids. Drought tolerant and non-DT hybrid pairs of similar maturity were planted in six site-years with different soil types, seasonal evapotranspiration (ET), and vapor pressure deficit (VPD), representing a range of macro-environments. Irrigation regimes and seeding rates were used to create several micro-environments within each macro-environment. Hybrid response to the range of macro and micro-environmental stresses were characterized in terms of water use efficiency, grain yield, and environmental index. Yield advantage of DT hybrids was positively correlated with environment ET and VPD. Drought tolerant hybrids yielded 5 to 7% more than non-DT hybrids in high and medium ET environments (>430 mm ET), corresponding to seasonal VPD greater than 1200 Pa. Environmental index analysis confirmed that DT hybrids were superior in stressful environments. Yield advantage for DT hybrids appeared as yield dropped below 10.8 Mg ha-1 and averaged as much as 0.6–1 Mg ha-1 at the low yield range. Hybrids with DT technology can offer a degree of buffering against drought stress by minimizing yield reduction, but also maintaining a comparable yield potential in high yielding environments. Further studies should focus on the physiological mechanisms presented in the commercially available corn drought tolerant hybrids.

Inoculation of Brassica oxyrrhina with plant growth promoting bacteria for the improvement of heavy metal phytoremediation under drought conditions

The aim of this study was to investigate the effects of drought resistant serpentine rhizobacteria on plant growth and metal uptake by Brassica oxyrrhina under drought stress (DS) condition. Two drought resistant serpentine rhizobacterial strains namely Pseudomonas libanensis TR1 and Pseudomonas reactans Ph3R3 were selected based on their ability to stimulate seedling growth in roll towel assay. Further assessment on plant growth promoting (PGP) parameters revealed their ability to produce indole-3-acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase. Moreover, both strains exhibited high resistance to various heavy metals, antibiotics, salinity and extreme temperature. Inoculation of TR1 and Ph3R3 significantly increased plant growth, leaf relative water and pigment content of B. oxyrrhina, whereas decreased concentrations of proline and malondialdehyde in leaves under metal stress in the absence and presence of DS. Regardless of soil water conditions, TR1 and Ph3R3 greatly improved organ metal concentrations, translocation and bioconcentration factors of Cu and Zn. The successful colonization and metabolic activities of P. libanensis TR1 and P. reactans Ph3R3 represented positive effects on plant development and metal phytoremediation under DS. These results indicate that these strains could be used as bio-inoculants for the improvement of phytoremediation of metal polluted soils under semiarid conditions.

Response of Germination Physiology ofCajanus cajanSeeds to Drought Stress: Comparison Between Karst Water and Allogenic Water Treatments

In this paper, responses of germination physiology of pigeon pea (Cajanus cajan) seeds to drought stress in karst water environment and non-karst (allogenic) water environment were studied to explore the adaptability of pigeon pea to karst environment. The results showed that: (i) Under drought stress of 20% PEG-6000, the germination rate, vigor index, germination index and biomass of pigeon pea seeds on day 7 cultivated with karst water were all greater than that of the allogenic water treatment group, while the seed germination stress index was significantly smaller than that of the allogenic water treatment group, suggesting that karst water environment was more favorable to pigeon pea seed germination, (ii) Without drought stress, the malondialdehyde (MDA) and superoxide dismutase (SOD) activities of pigeon pea seeds cultivated with karst water were all smaller than that of the allogenic water group. However, under drought stress, the SOD activity was significantly higher than that of allogenic water group, suggesting pigeon pea SOD in karst water was able to more rapidly respond to external drought stress, and increase its own activity to reduce the damage to the plants. And (iii) with and without drought stress, the soluble protein level of the karst water group was higher than that of the allogenic water group, while the free amino acid level was lower than that of the allogenic water group. This difference was more significant with the presence of drought stress, suggesting that the karst water environment was more favorable to the accumulation of soluble proteins and thus produced larger biomass. Hence, pigeon pea is a tree species that is adapted to high-calcium, alkaline environments in karst areas, and is of great significance for the revegetation and rocky desertification control in mountainous karst areas.

&amp;lt;i&amp;gt;In Vitro&amp;lt;/i&amp;gt; Evaluation of Some Traits in &amp;lt;i&amp;gt;Stevia rebaudiana&amp;lt;/i&amp;gt; (Bertoni) under Drought Stress and Their Relationship on Stevioside Content

The experiment was conducted to evaluate the differences of plant growth as well as sweetener material of two types of Stevia rebaudiana under conditions of absence and presence of drought stress. In vitro, the experiment was conducted as drought traits using four levels of polyethylene glycol (0.0, 10,000, 20,000, 30,000 ppm). It was observed that survival % and No. of shoots should be considered as the important factors associated with stevioside content in stevia plant. According to path coefficient analysis and positive direct effect of studied traits, survival % recorded the highest value (0.5386), whereas No. of shoots recorded the highest value (– 0.8827) as negative direct effect in related to stevioside content. The results showed that all traits were affected, especially under 30,000 ppm level of polyethylene glycol. Generally, the most of studies traits exhibited a recorded clearly difference between the two types and used drought levels on stevia plants. Therefore, selection based on survival % would be more effective to improving stevioside content of stevia plants in drought stress conditions.

The dynamic isohydric-anisohydric behavior of plants upon fruit development: taking a risk for the next generation.

Maintaining plant water status above a critical threshold is a crucial necessity for plant growth and reproduction. However, the factors that determine this threshold level and the ways in which it is regulated vary greatly between species and even across the life cycle of individual species. Isohydric waterbalance behavior involves the maintenance of a constant leaf water potential at midday, which is similar in well-irrigated plants and under drought conditions. In contrast, plants exhibiting anisohydric behavior have markedly decreased water potentials following the evaporative demand experienced during the day. This permits lower leaf water potentials in the presence of drought stress (Tardieu and Simonneau 1998). It has been suggested that the core physiological parameter thresh

Combining ability, indirect and correlated response to selection for oil yield in sunflower (Helianthus annuus) under contrasting moisture environments

Sunflower (Helianthus annuus L.) production in South Africa depends on natural rainfall which is variable and unpredictable, hence the need to develop drought tolerant sunflower genotypes to stabilise production under random stress environments. An exploratory research study was undertaken to determine the effectiveness of using moisture stress selection environments and three secondary traits, head diameter (HD), stem diameter (SD) and stay green canopy (SG) in developing drought tolerant sunflower cultivars with high oil yield (OY) in the presence of drought stress. A total of 84 testcross hybrids (TCHs) developed by crossing two testers to 42 female cytoplasmic male sterile (CMS) inbred lines were evaluated in nine environments for oil yield and other agronomic traits. The environments were classified as random drought stress environments (RSE), managed drought stress environments (MSE) and non-stress environments (NSE). Type A and type B genetic correlations based on broad sense heritability (H2) and narrow sense heritability (h2), respectively were estimated to quantify indirect selection efficiency. Type A genetic correlations indicated that SG had the potential to be used as a secondary trait to indirectly improve OY. The indirect selection efficiency (ISE) for OY via SG using genetic correlation based on H2 were 0.79, 0.82 and 0.78 in the RSE, MSE and NSE, respectively and genetic correlation based on h2 were 0.67, 0.98, and 0.93 in the RSE, MSE and NSE, respectively. In both cases, selection in the MSE had the highest ISE. Estimates of indirect selection based on type B genetic correlation indicated that indirect selection for OY in the MSE and NSE for the RSE was as effective as direct selection for OY in the RSE based on the additive genetic correlations of 0.96 obtained in both selection environments. Overall, the results from this exploratory study should inform the development of breeding strategies to improve the drought tolerance of sunflower cultivars grown in South Africa and associated environments.

Differential responses of red clover germplasms to aluminum stress

Abstract Toxic levels of aluminum can cause severe yield reduction in red clover (Trifolium pratense L.), especially in the presence of drought stress. Aluminum tolerances of 17 red clover cultivars and germplasms representing a broad genetic base were evaluated in a Monmouth soil [26.2% Al saturation (pH 4.8) vs. 2.8% Al saturation (pH 5.7)] and in nutrient solutions (0 vs 111 μM Al; pH 4.5). The soil and nutrient culture studies were harvested 29 and 27 d after seeding, respectively. Aluminum stress reduced shoot and root growth significantly in soil but not in nutrient culture. Entries differed significantly in shoot vigor in both media and in root vigor in nutrient culture; responses to the two media were positively correlated. Relative weights (dry weight stressed/dry weight unstressed) in soil and nutrient culture were not correlated. In soil, Al stress significantly reduced shoot growth of all entries except ‘Tristan’, whereas root growth was not affected significantly in ‘Atlas’, ‘Lakeland’, ‘Pers...

Differential responses of alfalfa cultivars to aluminum stress

Abstract Toxic levels of aluminum can cause severe yield reduction in alfalfa (Medicago sativa L.), especially in the presence of drought stress. Reactions to Al stress of alfalfa cultivars and germplasms, representing a broad genetic base and the entire range of dormancy types, were evaluated in a Monmouth soil study [26.2% Al saturation (pH 4.8) vs 2.8% Al saturation (pH 5.7)] and in two nutrient solution experiments (0 vs 111 μmol Al; pH 4.5). The soil study, Experiment 1, and Experiment 2 were harvested 28, 40, and 25 d after seeding, respectively. In all studies, entries differed significantly in vigor and yields were reduced significantly by Al stress. In the soil study, only ‘Lahontan’ was not affected significantly by Al stress, although Lahontan, ‘Atlantic’, ‘B13‐A14’ (tolerant check), ‘Ladak 65’, and ‘Mesa‐Slrsa’ had comparable relative weights (dry weight stressed/dry weight unstressed). There were no statistically significant differential responses to Al stress in Experiment 1, however the rel...

Annual index

The aim of this study was to investigate the effects of drought resistant serpentine rhizobacteria on plant growth and metal uptake by Brassica oxyrrhina under drought stress (DS) condition. Two drought resistant serpentine rhizobacterial strains namely Pseudomonas libanensis TR1 and Pseudomonas reactans Ph3R3 were selected based on their ability to stimulate seedling growth in roll towel assay. Further assessment on plant growth promoting (PGP) parameters revealed their ability to produce indole-3-acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase. Moreover, both strains exhibited high resistance to various heavy metals, antibiotics, salinity and extreme temperature. Inoculation of TR1 and Ph3R3 significantly increased plant growth, leaf relative water and pigment content of B. oxyrrhina, whereas decreased concentrations of proline and malondialdehyde in leaves under metal stress in the absence and presence of DS. Regardless of soil water conditions, TR1 and Ph3R3 greatly improved organ metal concentrations, translocation and bioconcentration factors of Cu and Zn. The successful colonization and metabolic activities of P. libanensis TR1 and P. reactans Ph3R3 represented positive effects on plant development and metal phytoremediation under DS. These results indicate that these strains could be used as bio-inoculants for the improvement of phytoremediation of metal polluted soils under semiarid conditions.