Combination Of Drought Stress Research Articles

The Formation of Water Stress Resistant Soybean Varieties From Genotypes Resulted From Genetic Mutation Between the Second Generation Mutant With High Result Potentials

The aim of the study was to obtain second generation mutant lines (M2) from three gene-mutated soybean seeds, namely M2 Anjasmoro, M2 Argomulyo and M2 Dena-1 which are tolerant to drought stress, water saturation stress and high yield potential. The research was carried out in the Maros district, South Sulawesi, July-November 2022, arranged in a split plot design. The main plot is the application of water consisting of three levels, namely selection of drought stress (C1), selection of water saturation stress (C2) and selection of optimum conditions (C3). Subplots are three second generation soybean seeds resulting from gene mutations (M2), namely: M2 Anjasmoro, M2 Argomulyo and M2 Dena-1. The results showed that the best plant agronomic characters for growth and production factors were M2 Anjasmoro for water saturation stress treatment and M2 Argomulyo and M2 Dena-1 for drought stress treatment. The fastest harvesting age was obtained from the combination of drought stress and M2 Argomulyo, namely 79 days and not significantly different from the combination of drought stress and M2 Dena-1, namely 79.34 days, but significantly different from the other treatment combinations. The production obtained from the seeds resulting from the second generation of gene mutations has begun to show a difference between those given the mutation treatment and their parents, where the combination of water saturation stress and M2 Anjasmoro gave the highest production of 3.20 tonnes/ha higher than the production of its parents which only reached 2. .03-2.25 tonnes/ha. Generation M2 Argomulyo seeds were the longest surviving seeds to recovery from drought stress (38 days), in the sense that M2 Argomulyo seeds were more resistant to drought stress than the other two generations of seeds, namely M2 Anjasmoro (36 days) and M2 Dena-1 (37 days). Meanwhile, the resistance to water saturation was shown by M2 Dena-1 generation seeds, namely 40.67 days, followed by M2 Argomulyo 29.67 days and M2 Anjasmoro 27.33 days.

Barley shows reduced Fusarium head blight under drought and modular expression of differentially expressed genes under combined stress.

Plants often face simultaneous abiotic and biotic stress conditions; however, physiological and transcriptional responses under such combined stress conditions are still not fully understood. Spring barley (Hordeum vulgare) is susceptible to Fusarium head blight (FHB), which is strongly affected by weather conditions. We therefore studied the potential influence of drought on FHB severity and plant responses in three varieties of different susceptibility. We found strongly reduced FHB severity in susceptible varieties under drought. The number of differentially expressed genes (DEGs) and strength of transcriptomic regulation reflected the concentrations of physiological stress markers such as abscisic acid or fungal DNA contents. Infection-related gene expression was associated with susceptibility rather than resistance. Weighted gene co-expression network analysis revealed 18 modules of co-expressed genes that reflected the pathogen- or drought-response in the three varieties. A generally infection-related module contained co-expressed genes for defence, programmed cell death, and mycotoxin detoxification, indicating that the diverse genotypes used a similar defence strategy towards FHB, albeit with different degrees of success. Further, DEGs showed co-expression in drought- or genotype-associated modules that correlated with measured phytohormones or the osmolyte proline. The combination of drought stress with infection led to the highest numbers of DEGs and resulted in a modular composition of the single-stress responses rather than a specific transcriptional output.

Conferring of Drought and Heat Stress Tolerance in Wheat (Triticum aestivum L.) Genotypes and Their Response to Selenium Nanoparticles Application

In this study, the role of selenium nanoparticles (SeNPs, 10 mg·L-1) has been investigated in modulating the negative effects of drought and heat stresses on eight bread wheat (Triticum aestivum L.) genotype seedlings. Those genotypes included Giza-168, Giza-171, Misr-1, Misr-3, Shandweel-1, Sids-1, Sids-12, and Sids-14. The study included six treatments as follows: regular irrigation with 100% Field Capacity (FC) at a temperature of 23 ± 3 °C (T1), drought stress with 60% FC (T2), heat stress of 38 °C for 5 h·day-1 (T3), foliar spray of 10 mg·L-1 of SeNPs only (T4), a combination of drought stress with foliar spray of 10 mg·L-1 of SeNPs (T5), and heat stress with foliar spray of 10 mg·L-1 of SeNPs (T6). The experiment continued for 31 days. Foliar application of SeNPs improved the plant growth, morpho-physiological and biochemical responses, and expression of stress-responsive genes in wheat (T. aestivum L.) seedlings. Overall, morpho-physiological traits such as plant height (PH), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), and root dry weight (RDW) of wheat genotypes grown under different conditions ranged from 25.37-51.51 cm, 3.29-5.15 g, 0.50-1.97 g, 0.72-4.21 g, and 0.11-1.23 g, respectively. From the morpho-physiological perspective, drought stress had a greater detrimental impact on wheat plants than heat stress, whereas heat stress significantly impacted the expression of stress-responsive genes. Stress responses to drought and heat varied between wheat genotypes, suggesting that different genotypes are more resilient to stress. Exogenous spraying of 10 mg·L-1 of SeNPs improved the photosynthetic pigments, photosynthetic rate, gas exchange, and transpiration rate of wheat plants and enhanced drought and heat tolerance by increasing the activity of antioxidant enzymes including catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) and the expression level of stress-responsive genes. Our results showed that spraying wheat seedlings with 10 mg·L-1 of SeNPs enhanced SOD activity for all genotypes as compared to the control, with the Sids-12 genotype having the highest value (196.43 U·mg-1 FW·min-1) and the Giza-168 genotype having the lowest (152.30 U·mg-1 FW·min-1). The expression of PIP1, LEA-1, HSP70, and HSP90 stress-responsive genes was more significant in tolerant genotypes (Giza-171 and Giza-168) than in sensitive ones (Misr-1 and Misr-3) in response to drought and heat stresses. Under stress conditions, the shoot and root fresh weights, photosynthetic pigment content, stomatal conductance (SC), and transpiration rate (TR) were positively correlated with plant height (PH), while root and shoot dry weights, malondialdehyde (MDA), proline, hydrogen peroxide (H2O2), and APX were negatively correlated. Multivariate analysis and biplot results revealed that genotypes Giza-168, Giza-171, Sids-12, and Sids-14 performed well in both stress situations and were classified as stress-tolerant genotypes. These best genotypes may be employed in future breeding projects as tools to face climate change. This study concluded that various physio-biochemicals and gene expression attributes under drought and heat stress could be modulated by foliar application of SeNPs in wheat genotypes, potentially alleviating the adverse effects of drought and heat stress.

Sweetpotato cultivars responses to interactive effects of warming, drought, and elevated carbon dioxide.

Plants are sensitive to changes projected in climates, such as elevated carbon dioxide (eCO2), high temperature (T), and drought stress (DS), which affect crop growth, development, and yield. These stresses, either alone or in combination, affect all aspects of sweetpotato plant growth and development, including storage root development and yield. We tested three sweetpotato cultivars (Beauregard, Hatteras, and LA1188) responses to eight treatments (Control, DS, T, eCO2, DS + T, T + eCO2, DS + eCO2, DS + T + eCO2). All treatments were imposed 36days after transplanting (DAP) and continued for 47days. Treatments substantially affected gas exchange, photosynthetic pigments, growth, and storage root components. Cultivars differed considerably for many of the measured parameters. The most significant negative impact of DS was recorded for the shoot and root weights. The combination of DS + T had a significant negative effect on storage root parameters. eCO2 alleviated some of the damaging effects of DS and high T in sweetpotato. For instance, eCO2 alone or combined with DS increased the storage root weights by 22% or 42% across all three cultivars, respectively. Based on the stress response index, cultivar "Hatteras" was most tolerant to individual and interactive stresses, and "LA 1188" was sensitive. Our findings suggest that eCO2 negates the negative impact of T or DS on the growth and yield of sweetpotato. We identified a set of individual and interactive stress-tolerant traits that can help select stress cultivars or breed new lines for future environments.

GROWTH OF CELERY (Apium graveolens L.) AFTER TREATMENT OF DROUGHT STRESS AND CULTURE Trichoderma harzianum

<p>Celery is a plant that is sensitive to drought stress. The availabillity of water is one factor that affect the growth of celery plants. Stunted plant growth caused by dry conditions of water in the planting media. Treatment of fungus <em>Trichoderma harzianum</em> in planting media is expected to overcome drought stress. This study aims to find out the effect of giving fungus <em>Trichoderma harzianum</em> on the growth of celery plants under drought stress conditions. This research was conducted from September 2020 to January 2021. The research design used was a completely randomized design with a factorial pattern consisting of 2 factors with 5 replications. The first factor is watering time (P) consists of watering every day (P1), every 4 days (P2), every 6 days (P3), every 8 days (P4), and every 10 days (P5). The second factor is fungus <em>Trichoderma harzianum</em> consists of 0 g/kg (T1), 25 g/kg (T2), 50 g/kg (T3), 75 g/kg (T4), and 100 g/kg (T5). The result showed that the drought stress treatment had a significant effect on the parameters of plant height, root volume and root wet weight. Treatment fungus <em>Trichoderma harzianum</em> significant effect on plant height parameters, while the combination of drought stress and treatment fungus <em>Trichoderma harzianum</em> did not significantly affect all growth parameters.</p>

Responses of the Photosynthetic Electron Transport Reactions Stimulate the Oxidation of the Reaction Center Chlorophyll of Photosystem I, P700, under Drought and High Temperatures in Rice.

It is of interest how photosynthetic electron transport (PET) reactions respond to excess light energy caused by the combination of drought stress and high temperatures. Since such information is scarcely available for photosystem I (PSI), this question was explored in rice (Oryza sativa L.) plants subjected to drought stress, using culture solutions that contain poly(ethylene glycol) at different concentrations under two day/night temperature regimes. At 27/22 °C (day/night), drought stress led to the oxidation of the reaction center of the chlorophyll of PSI (P700), and also led to decreases in the quantum efficiencies of photosystem II (PSII) and PSI, and a reduction of the primary quinone electron acceptor of PSI. Such drought stress responses were wholly stimulated at 35/30 °C. These parameters were strongly correlated with each other and were minimally affected by temperature. These results indicate that the drought stress responses of the respective PET reactions are closely associated with each other in the oxidization of P700 and that such responses are stimulated at high temperatures. The underlying mechanisms of these phenomena were discussed. While P700 oxidation is thought to suppress reactive oxygen species (ROS) production, PSI photoinhibition was observed under severe stress conditions, implying that P700 oxidation is not sufficient for the protection of PSI under drought stress.

Influence of drought and season on compartmentalization of black locust (Robinia pseudoacacia L.) inoculated with Armillaria mellea

Effective compartmentalization of wounds in trees prevents the spreading of decay in wood. Climate extremes including drought can reduce the ability of trees to compartmentalize. In addition, compartmentalization of winter wounds is considered to be weaker than of summer wounds. A combination of drought-stress, winter injury and infection can entirely prevent the compartmentalization and can thus be the major cause for declining tree vitality. For deeper insight into the interaction of climate extremes such as drought and defense responses of trees, the defense reactions of black locust (Robinia pseudoacacia L.) saplings, both well-watered and drought-stressed, to wounding or the pathogen Armillaria mellea were studied. The pathogen was inoculated either in the growth period or during dormancy. All saplings were harvested at the same time, thus, 24 months after inoculation during the growing season and 18 months after inoculation during dormancy, and the extent and effectiveness of compartmentalization were analyzed. Regardless of the season of wounding and infection, the axial spread of discoloration was significantly shorter and the woundwood was almost twice as thick in well-watered compared to drought-stressed saplings. In drought-stressed saplings inoculated in the dormant season, the wounds were not at all sealed and compartmentalized. In these saplings, the presence and spread of the pathogen could be confirmed in the surrounding tissues of the wound. In contrast, the pathogen was not confirmed in tissues of well-watered and drought-stressed saplings inoculated in the active season. To conclude, the well-watered saplings were better able to compartmentalize, and the drought-stressed saplings inoculated in the dormant season, were weakest against wounding and infection and failed to compartmentalize effectively.

灌浆前期高温和干旱胁迫对小麦籽粒蛋白质含量和氮代谢关键酶活性的影响

To explore the physiological mechanisms of stresses on nitrogen metabolism and protein accumulation in wheat grains,a pot experiment was performed at the Scientific Educational Park of Henan Agricultural University from 2010 to2012. Zhengmai 366 and Yunong 949,wheat cultivars with different gluten-strengths,were grown in 24-cm pots with 10 kg loam soil for the experiment,which was performed using a completely randomized design in three replicates. Plants were initially grown in the field environment and were then transferred to a climate-controlled greenhouse for the high temperature( HT) treatment. HT began from the 8thday after anthesis( DAA) and ended at the 11 thDAA,with a high temperature of38°C for five hours from 11: 00 to 16: 00,after which the plants were returned to the field environment. The concentration of protein and its components,and the activities of glutamine synthetase( GS) and glutamic-pyruvic transaminase( GPT)in the grains were measured to evaluate the effects of the stresses. The results showed that HT,drought stress( DS) andtheir combination significantly increased protein and its components' concentrations,yet decreased the ratio of glutenin to gliadin. The protein accumulation was also reduced by stresses. For example,for Zhengmai 366,the protein yield significantly decreased by 20. 7% under HT,by 16. 2% under DS,and by 26. 1% under a combination of HT and DS. In Yunong 949,the protein yield decreased by 12. 4% under HT,by 11. 9% under DS and by 15. 8% under a combination of HT and DS. The grain weight significantly declined by 23. 2% under HT,by 18. 0% under DS and by 29. 9% under a combination of HT and DS,in Zhengmai 366,and decreased by 24. 0% under HT,by 16. 0% under DS,and by 29. 9%under a combination of HT and DS,in Yunong 949. However,the activities of GS and GPT were promoted under HT,DS and their combination. A correlation analysis showed that the activity of GS was positively correlated with the protein concentration in mature wheat grains at significant or extremely significant levels at 8,17,23,and 29 DAA. However,GS activity was negatively correlated with protein yield at extremely significant levels at 23 and 35 DAA,and it was negatively correlated with grain yield at significant or extremely significant levels at 8,17,23,29 and 35 DAA. The activity of GPT was positively correlated with protein concentration at extremely significant levels at 11 and 17 DAA. However,GPT activity was negatively correlated with protein yield at extremely significant levels at 8,17 and 23 DAA and negatively correlated with grain yield at significant or extremely significant levels at 8,11,17 and 23 DAA. The results also indicated that,under the present experimental conditions,the influence of the HT treatment was greater than that of the DS,and an overlap effect existed between HT and DS. In addition,Zhengmai 366,a high-gluten cultivar,showed more sensitivity to stresses than Yunong 949,a mid-gluten cultivar. These results may aid in understanding how HT and DS influence protein accumulation and may be useful in improving wheat quality.

Genotypic variation in drought stress response and subsequent recovery of wheat (Triticum aestivum L.)

Three wheat (Triticum aestivum L.) genotypes, Sadovo, Katya and Prelom, with different tolerance to drought were comparatively evaluated in terms of leaf respiratory responses to progressing dehydration and consecutive rewatering. Under drought stress, the respiration of all varieties gradually decreased, as the drought-tolerant Katya showed the most pronounced decline at earlier stages of dehydration. When water stress intensified, this genotype gave relatively stable respiration rates compared with the drought-sensitive varieties. Additionally, dehydrated Katya leaves displayed lower stomatal conductance and higher photosynthesis values, which resulted in greater water use efficiency during the dehydration period. Combination of drought stress and short-term changes in leaf temperature also induced genotype-specific response that differed from the response to drought only. Over the whole temperature range, the leaves of Katya exposed to dehydration for 14days, showed higher respiration rates compared to the drought-sensitive varieties. The sensitive varieties maintained higher respiration rates under control conditions and mild dehydration, and very low rates under severe drought. In Katya, respiration and photosynthesis were fully restored from the stress within the first day of rewatering. The drought-sensitive genotypes displayed a considerably slower recovering capacity. The results are discussed in terms of possible physiological mechanisms underlying plant tolerance to drought.

Ecophysiological responses ofAbies fabriseedlings to drought stress and nitrogen supply

Abies fabri (Mast.) Craib. (A. fabri) is an endemic and dominant species in typical subalpine dark coniferous forests distributed in mountainous regions of Western Sichuan, China. We investigated the ecophysiological responses of A. fabri seedlings to short-term experimental drought, nitrogen supply and their interaction. Drought stress was created by excluding natural precipitation with automatically controlled plastic roof that covered the seedlings. Nitrogen fertilization was applied weekly by spraying over seedlings ammonium nitrate solution (50 kg N ha(-1) year(-1)) during the growing season of 2009. The results showed that drought stress decreased leaf relative water content (RWC), whereas it caused marked increases in root mass ratio (RMR) and root/shoot mass ratio by 6.19 and 10.39%, respectively, as compared with the control. Drought stress increased malondialdehyde (MDA) content, electrolyte leakage, proline content, soluble sugars content and the activities of antioxidant enzymes, whereas nitrogen supply decreased MDA content, but enhanced activities of some antioxidant enzymes [especially peroxidase (POD)]. In the drought stressed plots, nitrogen supply increased RWC and decreased the content of MDA. The combination of drought stress and nitrogen supply also decreased the activities of antioxidant enzymes. These results indicated that the negative effects of drought stress on A. fabri seedlings might be alleviated by nitrogen supply.

Differential response of two Central-European oak species to single and combined stress factors

We studied the effects of repeated defoliation and drought, which are considered to be most effective in triggering oak decline, on the Central-European oak species Quercus robur L. and Quercus petraea [Matt.] Liebl. Three-year-old saplings were subjected to artificial defoliation in two consecutive years and to drought stress, applied singly or in combination. Differences in the morphological, anatomical and physiological responses to these stress factors among treatments and between species were tested in a 3-year experiment. Drought stress lowered the pre-dawn and the afternoon leaf-water potentials in both species, irrespective of additional defoliation. The relative water content of the leaves was unaffected by drought stress; but, in Q. robur, it decreased in trees subjected to defoliation and to the combination of drought stress and defoliation. When repeated defoliation and drought stress were applied within the same growing season, the leaf-to-air difference in the partial pressure of water vapour (Δw) explained most of the variation in the daily integral of the stomatal conductance to water vapour (gs day sum) in Q. petraea; however, in Q. robur, the hydraulic conductance of the twigs was the most powerful predictor variable. In the same year, the actual hydraulic conductance was correlated with gs day sum in Q. robur, but not in Q. petraea. The studied parameters of gas exchange and biomass production revealed that Q. robur recovered more rapidly from stress than did Q. petraea. We hypothesize that this is due to Q. robur‘s lower responsiveness to the environmental variable Δw and its higher responsiveness to internal hydraulic conductance compared to Q. petraea.