Drought Damage Research Articles

Physiological and metabolomic analyses reveal the mechanism by which exogenous spermine improves drought resistance in alfalfa leaves (Medicago sativa L.).

Alfalfa (Medicago sativa L.) is a globally important legume crop with high nutritional and ecological value. Drought poses a serious threat to alfalfa acreage and yields. Spermine (Spm) has been shown to protect plants from drought damage. The aim of this study was to clarify the mechanism of exogenous Spm to improve drought resistance of alfalfa. In this study, we root applied 0.1, 0.5, and 1 mM Spm to Gannong No. 3 (G3) alfalfa under drought stress, and then determined their physiological and metabolic changes. The results showed that exogenous Spm increased chlorophyll content, chlorophyll fluorescence parameters and gas exchange parameters, enhanced antioxidant enzymes activity, improved ascorbic acid-glutathione (AsA-GSH) cycle, increased osmoregulatory substances content, reduced hydrogen peroxide and superoxide anion levels, and inhibited malondialdehyde accumulation in alfalfa under drought stress, thereby increasing plant height and leaf relative water content and enhancing drought tolerance of alfalfa. The redundancy analysis of the above physiological indicators showed that the addition of the optimal Spm to improve drought tolerance of alfalfa under drought stress was mainly achieved by increasing catalase activity and improving the ASA-GSH cycle. In addition, metabolomics analysis revealed that exogenous Spm increased the content of oxobutanedioic acid, citric acid, fumaric acid and malic acid to enhance the tricarboxylic acid cycle. Meanwhile, exogenous Spm increased endogenous Spm and proline (Pro) content to resist drought stress by enhancing Spm and Pro metabolism. Moreover, exogenous Spm increased the accumulation of the signaling substance abscisic acid. In conclusion, exogenous Spm enhanced drought resistance of alfalfa leaves under drought stress.

Determination of Critical Crop Water Stress Index of Tea under Drought Stress Based on the Intercellular CO2 Concentration

Climatic changes have caused seasonal drought to occur frequently in tea fields of low-mountain and hill regions over the past decades. This leads to huge losses in the quality and yields of famous tea, which restricts the economic development of the tea industry. It is crucial to implement suitable irrigation scheduling. The crop water stress index (CWSI) is the main index to assess the water status of the crop. When the crop suffers irreversible drought stress, its critical water status cannot be easily evaluated using the CWSI. The change from stomatal limitations (SLs) to non-stomatal limitations (NSLs) of photosynthesis is vital for accurately recognizing crop drought stress. Thus, the objective of this research is to determine the critical crop water stress index of tea based on intercellular CO2 concentration (Ci) dynamic responses to drought stress. During two sensitive periods of water stress (famous tea harvest season and summer drought season, which are from March to April and July to August, respectively), the dynamic changes in the CWSI in tea were calculated and analyzed based on the CWSI theoretical model. The upper and lower baselines were determined on a daily basis and during a certain period. A critical value of the CWSI represents irreversible drought damage. This was determined by the characteristic response of the Ci of tea leaves during extreme drought stress. The results showed the following: (1) during the famous tea harvest season and summer drought season, the daily variation in CWSI was similar. During a certain period, the former maintained a stable fluctuation, while the latter increased in fluctuation. (2) The Ci showed a trend of fluctuating downward to a low point and then upward during extreme drought stress. After reaching the low point, it quickly increased in the former and stabilized for a day in the latter. When the Ci reached the low point, the upper benchmark of this critical point was 13.9 μmol·mol−1, the lower benchmark was 3.4, and the CWSI was 0.27. This critical CWSI could be used as an irrigation threshold point to ensure normal production for tea fields.

Network analysis of metabolomics, transcriptome and hormones reveals propionic acid-mediated novel survival strategy against drought in wheat.

Propionic acid (PA), a low-molecular-weight organic acid, is crucial to plant life metabolism. However, the regulatory mechanism of PA-mediated drought resistance in wheat remains largely unknown. Herein, we reported on a regulatory network of PA-mediated drought resistance in wheat using integrated transcriptome and metabolomics analysis and verified genes associated with drought resistance. Compared to the water-treated group, the application of PA alleviated the damage of drought by increasing plant water content, antioxidant enzyme activities and decreasing the malondialdehyde level (MDA). Transcriptome and metabolomics analysis revealed that PA triggered upregulation of key genes and metabolites, including TaBCAT, TaALDH6A1, TaALDH7A1, TaCHI, TaFLS, chrysin, and galangin, which were involved in valine, leucine and isoleucine degradation or flavonoid biosynthesis, respectively. In addition, the expression of genes encoding auxin-related transcription factors (TFs) strikingly increased, such as auxin/indoleacetic acid (AUX/IAA) and auxin response factor (ARF). Moreover, PA activated abscisic acid (ABA) and indole-3-acetic acid (IAA) signalling pathways. Taken together, our findings suggest that PA promotes energy metabolism and antioxidant activities to confer wheat drought resistance by introducing comprehensive and systemic effects of valine, leucine and isoleucine degradation flavonoid biosynthesis. Furthermore, activated AUX/IAA and ARF TFs might serve vital roles in drought resistance via modulating IAA signalling. This study provides novel insights into PA-mediated crop resistance and the improvement of the agroecological environment.

Innovations in economic assessment of drought: an application to the US southwest

ABSTRACT While numerous studies have examined the economic repercussions of drought, there remains a gap in integrated analyses comprehensively assessing its economic effects, especially where there is no drought adaptation policy under debate calling for a standard cost-benefit analysis. This work's first contribution comes from the development of a non-linear econometric model predicting total county income for several counties and years, for which population growth in some regions showed increasing water use despite the presence of drought. Using the arid southwest US state of New Mexico as a case study for the drought years of 2017–2019, this work develops a second innovation to assess drought damages based on comparing changes in per capita water use from 2015 to those later years. Using those two innovations, total economic damages to water users summed over the three drought years amount to $1.983 billion, just under 1% of the state's total income for that period. Overall, the effects of drought in New Mexico were more modest than anticipated partly because water users in this state showed remarkable resilience in handling water shortages due to several unique structural features of the state's income generation processes.

Evaluation of the benefits of plant growth-promoting rhizobacteria and mycorrhizal fungi on biochemical and morphophysiological traits of Aloe barbadensis Mill under water deficit stress

Aloe barbadensis is a drought-tolerant perennial medicinal plant with both nutritional and cosmetic uses. Drought is one of the main abiotic stresses limiting plant growth and development. However, the use of drought-resistant plants combined with beneficial soil micro-organisms could improve the effectiveness of biological methods to mitigate drought damage. This research aims to evaluate the effects of Funneliformis mosseae (MF), plant growth-promoting rhizobacteria (PGPR) (including Pseudomonas putida and Pantoea agglomerans), and their co-inoculation on the macronutrient status, antioxidant enzyme activities, and other morphophysiological traits of A. barbadensis under four irrigation regimes [25%, 50%, 75% and 100% of water requirement (WR)]. Three harvests were conducted, revealing that inoculation enhanced the survival rate and shoot fresh weight (SFW) compared to the control plants. However, at 25% WR, the SFW was reduced by 43% more than the control. across all harvests, while the PGPR + MF treatment showed increases of more than 19%, 11%, and 17% compared to the control, MF, and PGPR treatments, respectively. The results also showed that A. barbadensis exhibited innate drought tolerance up to a 50% WR level by enhancing physiological defenses, such as antioxidant enzyme activity. Inoculation increased the macronutrient status of the plant at all levels of irrigation regimes especially under severe drought conditions. The highest levels of nitrogen (N) (16.24 mg g−1 DW) and phosphorus (P) (11.29 mg g−1 DW) were observed in the PGPR + MF treatment at 100% WR. The maximum relative water content under MF inoculation and 75% WR (98.24%) (98.24%) was reached. PGPR + MF treatment alleviated drought-induced osmotic stress, as indicated by reduced antioxidant enzyme activities and electrolyte leakage. However, P. putida and P. agglomerans strains alone or in combination with F. mosseae increased plant yield, macronutrient uptake and antioxidant enzyme activity. This study underscores the potential of these PGPR and MF strains as invaluable biological tools for the cultivation of A. barbadensis in regions with severe drought stress.

Towards an objective assessment of tree vitality: a case study based on 3D laser scanning

Key messageAnalyzing fine branch length characteristics in beech trees using single-tree QSMs derived from laser scanning reveals insights into drought-induced changes in vitality, which include branch shedding and reduced shoot growth.Climate change causes increasing temperatures and precipitation anomalies, which result in deteriorations of tree health and declines in ecosystem services of forests. It is therefore crucial to monitor tree vitality to preserve forests and their functions. However, methods describing tree vitality in situ are lacking reproducibility or are too laborious. Thus, we tested a laser-scanning based approach, assuming that an objective measurement of a tree’s outer shape should reveal changes according to tree vitality. QSMs of similarly sized beech trees from stands with varying degrees of drought damage were used. Absolute and relative fine branch lengths, their ratio to lower order branches’ lengths and their progressions over relative height were targeted to identify fine branch dieback and reduced growth. The absolute fine branch length was significantly lower for less vital beech trees, especially within the upper crown, leading to a less top-heavy vertical distribution of fine branches and a reduced fine-to-base order branch length ratio. Hence, height-dependent characteristics of fine branch lengths differed between vitalities. We conclude that using fine branch length characteristics derived from QSMs can be helpful in vitality assessments of beech trees. Still, uncertainties with regard to the plotwise assessment and problems with QSM quality are present.

Analysis of Economic Ripple Effects in the Agricultural Field Using Input–Output Analysis: Drought Damage in Korea in 2018

This study investigates the economic impact of the 2018 agricultural drought in Korea on the agricultural field through input–output analysis. Using industry linkage tables provided by the Bank of Korea, various economic impacts, including socio-economic and industry linkage effects, such as production, value added inducement effects, and employment inducement effects in the agricultural field, were analyzed. Our findings show the following: (1) It was found that an increase of 1 billion KRW (South Korean won) in output of agricultural, forestry, and fishery products induces an average of 0.6544 KRW in production inducement effects in other industries, 0.23756 KRW in value-added inducement effects, and 3.11363 in employment inducement effects per 1 billion KRW. (2) The supply shortage effect of agricultural, forestry, and fishery products was analyzed to cause a decrease in production of 2.3932 KRW across all industries, and the price inducing effect of a 10% increase in price was found to be 0.19400%, on average. The highest production inducement effects in the food and beverage industry (0.16514 KRW) and the highest value-added inducement effects (0.04391 KRW) came from agricultural, forestry, and fishery products. (3) In the industry linkage effect analysis, agricultural, forestry, and fishery products were found to have a forward linkage coefficient of 0.95652 and a backward linkage coefficient of 0.98911. It is implied by this result that the economic impact of agriculture on other industrial sectors is not significant. This study emphasizes the economic importance of agriculture by providing analytical results that can be utilized in agricultural policy formulation and economic decision-making. It can be used as an important basis for policy development for sustainable development and economic stability of the agricultural field. It can also contribute to a better understanding of how agriculture interacts with other industrial sectors and to the development of effective response strategies to natural disasters such as agricultural drought.

Ascophyllum nodosum seaweed extract and potassium alleviate drought damage in tomato by improving plant water relations, photosynthetic performance, and stomatal function

Ascophyllum nodosum seaweed extract and potassium alleviate drought damage in tomato by improving plant water relations, photosynthetic performance, and stomatal function

Development and Applicability Evaluation of Damage Scale Analysis Techniques for Agricultural Drought

In recent years, the intensity and frequency of droughts have been increasing with the advent of the climate crisis. Agricultural droughts have a significant economic and social impact. Agricultural drought is not only a natural disaster but also leads to food security threats and reduced economic activities, such as decreased productivity. Therefore, it is very important to specify the scale of agricultural drought and quantitatively estimate the economic damage. In this study, we developed an analytical methodology to quantitatively assess the economic damage of agricultural drought and estimated the damage of agricultural drought in 2018 and 2019 for the Republic of Korea. The 2018 agricultural drought was estimated to have caused USD 4.438 million in damage cost and USD 5.180 million in recovery cost. The 2019 drought was less damaging than the previous year, with an estimated damage cost of USD 286,000 and recovery costs of USD 218,000. The results suggest that the economic impact of agricultural drought varies by region depending on the frequency and intensity of the drought and confirm the importance of regional strategies for effective drought management and response. The impacts of agricultural drought go beyond short-term agricultural losses and lead to long-term economic burdens. Therefore, the results of this study are expected to be used as a basis for understanding the impacts of agricultural drought on national economies and for developing policies and strategies to minimize impacts.

Precision Estimation of Crop Coefficient for Maize Cultivation Using High-Resolution Satellite Imagery to Enhance Evapotranspiration Assessment in Agriculture.

The estimation of crop evapotranspiration (ETc) is crucial for irrigation water management, especially in arid regions. This can be particularly relevant in the Po Valley (Italy), where arable lands suffer from drought damages on an annual basis, causing drastic crop yield losses. This study presents a novel approach for vegetation-based estimation of crop evapotranspiration (ETc) for maize. Three years of high-resolution multispectral satellite (Sentinel-2)-based Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Red Edge Index (NDRE), and Leaf Area Index (LAI) time series data were used to derive crop coefficients of maize in nine plots at the Acqua Campus experimental farm of Irrigation Consortium for the Emilia Romagna Canal (CER), Italy. Since certain vegetation indices (VIs) (such as NDVI) have an exponential nature compared to the other indices, both linear and power regression models were evaluated to estimate the crop coefficient (Kc). In the context of linear regression, the correlations between Food and Agriculture Organization (FAO)-based Kc and NDWI, NDRE, NDVI, and LAI-based Kc were 0.833, 0.870, 0.886, and 0.771, respectively. Strong correlation values in the case of power regression (NDWI: 0.876, NDRE: 0.872, NDVI: 0.888, LAI: 0.746) indicated an alternative approach to provide crop coefficients for the vegetation period. The VI-based ETc values were calculated using reference evapotranspiration (ET0) and VI-based Kc. The weather station data of CER were used to calculate ET0 based on Penman-Monteith estimation. Out of the Vis, NDWI and NDVI-based ETc performed the best both in the cases of linear (NDWI RMSE: 0.43 ± 0.12; NDVI RMSE: 0.43 ± 0.095) and power (NDWI RMSE: 0.44 ± 0.116; NDVI RMSE: 0.44 ± 0.103) approaches. The findings affirm the efficacy of the developed methodology in accurately assessing the evapotranspiration rate. Consequently, it offers a more refined temporal estimation of water requirements for maize cultivation in the region.

Comparison of Morphological, Physiological, and Related Gene Expression Responses to Drought Stress in Five Camellia vietnamensis Cultivars

The main production area of Camellia vietnamensis (C. vietnamensis) is in the low mountain and hilly areas of southern China. The low survival rate of seedlings caused by drought is one of the main obstacles restricting the development of the C. vietnamensis industry. An exploration of the key adaptation mechanism of C. vietnamensis to drought stress is important in order to improve its drought resistance. We conducted a study on the morphological, physiological, biochemical, and drought resistance-related genes of five C. vietnamensis cultivars grown in Hainan province under varying degrees of drought stress. The results indicate that drought stress can lead to a decrease in the relative water content and photosynthetic capacity of C. vietnamensis leaves. Compared with the control, the drought damage index, malondialdehyde, relative electrical conductivity, soluble protein, soluble sugar and proline contents of the five C. vietnamensis cultivars increased with drought-stress duration and degree. With increasing drought-stress intensity, the activity of antioxidant enzymes and the content of related metabolites (total polyphenols, total flavonoids, tea saponins) gradually increased, and the expression levels of phenylpropanoid pathway-related genes (Cv4CL1, CvCAD1, CvCAD2, CvPOX1, CvPOX2, CvPOX3) were upregulated. Based on the results of the drought tolerance coefficients, principal component analysis, and hierarchical cluster analysis, we classified five C. vietnamensis cultivars into drought-tolerant cultivars (‘Haida 1’); moderately drought-tolerant cultivars (‘Haida 4’ and ‘Wanhai 4’); and drought-sensitive cultivars (‘Wanhai 3’ and ‘Wanhai 1’). The results of this study provide a theoretical basis for the promotion and cultivation of C. vietnamensis and the selection of drought-resistant cultivars.

Potassium attenuates drought damage by regulating sucrose metabolism and gene expression in sesame leaf

Drought has been considered the most restrictive environmental constraint on agricultural production worldwide. Photosynthetic carbohydrate metabolism is a critical biochemical process connected with crop production and quality traits. A pot experiment was carried out under four potassium (K) rates (0, 0.75, 1.5 and 2.25 g pot−1 of K, respectively) and two water regimes to investigate the role of K in activating defense mechanisms on sucrose metabolism against drought damage in sesame. The soil moisture contents are 75 ± 5% (well-watered, WW) and 45 ± 5% (drought stress, DS) of field capacity respectively. The results showed that DS plants without K application have lower activities of ribulose-1,5-bisphosphate carboxylase (Rubisco), sucrose phosphate synthase (SPS), soluble acid invertase (SAI), and chlorophyll content and higher activity of sucrose synthase (SuSy), which resulted in declined synthesis and distribution of photosynthetic products to reproductive organs. Under drought, there was a significant positive correlation between leaf sucrose metabolizing enzymes and sucrose content. Plants subjected to drought stress increased the concentrations of soluble sugar and sucrose to produce osmo-protectants and energy sources for plants acclimating to stress but decreased starch content. Conversely, K application enhanced the carbohydrate metabolism, biomass accumulation and partitioning, thereby contributing to higher seed oil and protein yield (28.8%–43.4% and 27.5%–40.7%) as compared to K-deficiency plants. The positive impacts of K application enhanced as increasing K rates, and it was more pronounced in drought conditions. Furthermore, K application upregulated the gene expression of SiMYB57, SiMYB155, SiMYB176 and SiMYB192 while downregulated SiMYB108 and SiMYB171 in drought conditions, which may help to alleviate drought susceptibility. Conclusively, our study illustrated that the enhanced photo-assimilation and translocation process caused by the changes in sucrose metabolism activities under K application as well as regulation of MYB gene expression contributes towards drought resistance of sesame.

Mitigation of water stress in broccoli by soil application of humic acid

The main challenge to plant productivity is water scarcity, which is predicted to get worse with climate change, particularly in arid and semi-arid areas. Humic acid could improve plant tolerance to mitigate drought damage, which is an effective strategy to improve crop production and agriculture sustainability under limited water conditions in these regions, but its effective application rates should also be established. Thus, two field experiments were carried out at the Qaha Vegetable Research Farm in Qalubia Governorate, Egypt, during the two seasons of 2020–21 and 2021–22 on clay soil. The present study investigated the effect of three rates of humic acid application (0, 4.8, and 9.6 kg ha-1) on growth, yield, and quality of broccoli cv. Montop F1 hybrid under well-watered and drought conditions. Drought was induced by missing alternate irrigation. Soluble humic acid as potassium-humate was applied three times with irrigation water at the time of the first three irrigations of drought treatment. Water-stressed plants had a decrease in growth, yield, leaf chlorophyll, and nutrient content, while they showed an increase in the contents of leaf proline and curd dry matter and total soluble solids as well as water use efficiency, in both seasons. Soil application of humic acid was effective in mitigating the adverse effects of water deficit stress on the growth and yield of broccoli. Water-stressed plants had the highest WUE value (9.32 and 9.36 kg m3−1 in the first and second seasons, respectively) when the maximal humic acid rate was applied. Humic acid at a high level (9.6 kg ha−1) had the most promising results and represents an opportunity that must be applied to improve broccoli yield and its production sustainability in arid and semiarid regions.

Prevention of drought damage through zeolite treatments onVitis vinifera: A promising sustainable solution for soil management

AbstractViticultural activity is intrinsically interlocked with climatic fluctuations and awful subjected to soil management. Increasing temperatures and reduced precipitation originate several alterations in the metabolic plant pathway and a depletion in grapes quality. The main aspiration of soil management is to keep and retain a microenvironment that considers all vine requirements to upgrade the balance between vegetative growth and cluster quality intensifying its resilience towards abiotic stress. Aiming to establish match and dissimilar drought stress responses among Sangiovese grapevines, we scouted ecophysiological and biochemical alterations after zeolite and irrigation soil application (combined and/or alone), using as control plants naturally exposed to abiotic stress in a Chianti Classico vineyard. When grapevines were exposed to water stress alone, the main reactions encompassed dwindled leaf midday water potential (Ψleaf) and increased proline content. These were accompanied by augments in zeaxanthin and lutein leaf contents, symptomatic of oxidative stress. Positive metabolic alterations in grapes triggered by zeolite and/or water showed some influence on the ripening of the berry differently depending on the year. They created a situation of resilience in berry avoiding arrest in the anthocyanin synthesis pathway during the warmest season and produced a more balanced maturation, closer to the objectives of the modern producer of classic Chianti (i.e. fresher and less alcoholic wines) during the fresher one. Under severe drought, it was activated the shikimic acid pathway and in stressed vines treatment, (WS) a reduction in malic acid content was found. Sugar and phenolic compounds were enhanced by zeolitic and undrought treatments. A negative effect enkindled by the drought and high temperatures combined with stress was the accumulation of quercetin‐3‐O‐rutinoside (Qrut), quercetin‐3‐O‐galactoside (Qgala), quercetin‐3‐O‐glucoside (Qgluc) and quercetin‐3‐O‐glucoronide (Qgluco) in WS treatment. These results summarize that clinoptilolite applied to the soil, both combined with water as well in purity, noteworthy protectorship from more detrimental repercussions of drought‐stressed grapevines, suggesting that new sustainable approaches in soil management are useful for the wellness of vines.

Impact of the 2015 El Niño event on Borneo: Detection of drought damage using solar-induced chlorophyll fluorescence

Impact of the 2015 El Niño event on Borneo: Detection of drought damage using solar-induced chlorophyll fluorescence

Magnesium supplementation alleviates drought damage during vegetative stage of soybean plants.

Our working hypothesis was that magnesium (Mg) supplementation modulates plant performance under low water availability and improves drought tolerance in soybean genotypes. Plants of Bônus 8579, M8808 and TMG1180 genotypes were grown under field conditions and subjected to three water stress treatments (control, moderate and severe stress) and three Mg levels [0.9 (low), 1.3 (adequate) and 1.7 cmolc dm-³ (supplementation)]. After 28 days of drought imposition, the growth parameters, osmotic potential, relative water content, leaf succulence, Mg content and photosynthetic pigments were assessed. In general, drought drastically decreased the growth in all genotypes, and the reductions were intensified from moderate to severe stress. Under adequate Mg supply, TMG1180 was the most drought-tolerant genotype among the soybean plants, but Mg supplementation did not improve its tolerance. Conversely, although the M8808 genotype displayed inexpressive responses to drought under adequate Mg, the Mg-supplemented plants were found to have surprisingly better growth performance under stress compared to Bônus 8579 and TMG1180, irrespective of drought regime. The improved growth of high Mg-treated M8808-stressed plants correlated with low osmotic potential and increased relative water content, as well as shoot Mg accumulation, resulting in increased photosynthetic pigments and culminating in the highest drought tolerance. The results clearly indicate that Mg supplementation is a potential tool for alleviating water stress in M8808 soybean plants. Our findings suggest that the enhanced Mg-induced plant acclimation resulted from increased water content in plant tissues and strategic regulation of Mg content and photosynthetic pigments.

Tree Condition and Analysis Program – Detecting Forest Disturbance at the Tree Level across the Contiguous United States with High Resolution Imagery

Abstract Effective management of forest insects and diseases requires detection of abnormal mortality, particularly among a single species, sufficiently early to enable effective management. Remote detection of individual trees crowns requires a spatial resolution not available from satellites such as Landsat or Sentinel-2. In the United States, there are currently few operational systems capable of effectively and affordably detecting and mapping tree mortality over broad landscapes using high-resolution imagery. Here, we introduce the Tree Condition and Analysis Program (TreeCAP), an open-source system that uses freely available imagery from the National Agriculture Imagery Program (NAIP) to create maps of tree condition (healthy or damaged). We demonstrate the potential applications of TreeCAP in four study sites: (1) beetle-killed pines in California, (2) emerald ash borer progression in Wisconsin, (3) hemlock wooly adelgid mortality in Pennsylvania, and (4) drought damage in Texas. We achieved an average overall accuracy of 87% across all study sites.

Exogenous strigolactones alleviate drought stress in wheat (Triticum aestivum L.) by promoting cell wall biogenesis to optimize root architecture

Exogenous strigolactones (SLs, GR24) are widely used to alleviate drought stress in wheat. The physiological and biochemical mechanisms via which SLs help overcome drought stress in wheat shoots have been reported; however, the mechanisms in wheat roots are unclear. The present study explored the effects of the exogenous application of SLs on wheat roots’ growth and molecular responses under drought stress using physiological analysis and RNA-seq. RNA-seq of roots showed that SLs mainly upregulated signal transduction genes (SIS8, CBL3, GLR2.8, LRK10L-2.4, CRK29, and CRK8) and transcription factors genes (ABR1, BHLH61, and MYB93). Besides, SLs upregulated a few downstream target genes, including antioxidant genes (PER2, GSTF1, and GSTU6), cell wall biogenesis genes (SUS4, ADF3, UGT13248, UGT85A24, UGT709G2, BGLU31, and LAC5), an aquaporin-encoding gene (TIP4-3), and dehydrin-encoding genes (DHN2, DHN3, and DHN4). As a result, SLs reduced oxidative damage, optimized root architecture, improved leaf-water relation, and alleviated drought damage. Thus, the present study provides novel insights into GR24-mediated drought stress management and a scientific basis for proposing GR24 application.

Comprehensive drought risk assessment using structural equation modeling and objective weighting methods

Study regionGyeongsang province in Korea Study focusDrought is a complex phenomenon influencing the natural, physical, and social sectors depending on the occurrence probability, regional characteristics, and the water supply and demand. To reduce the damage resulting from drought, it is necessary to assess the drought risk that can identify the impacts, causes, and vulnerability of drought. Previous drought risk assessment has usually been conducted by combining drought hazard and vulnerability, but such assessment is of limited value because the regional response capacity for drought is not considered. Moreover, it contains high uncertainty because indicators and weighting factors are determined by subjective methods. In this study, the comprehensive drought risk was assessed including the drought response capacity and with consideration of the regional water supply system. To remove the uncertainty in the drought risk assessment, this study employed partial least squares – structural equation modeling (PLS-SEM) to select effective indicators including the regional drought response capacity, and also applied objective weighting methods such as entropy, principal component analysis (PCA), Gaussian mixture model (GMM), and Bayesian networks to determine optimal weighting factors. New hydrological insights into the region under studyAs a result of application to Gyeongsang province in Korea, PLS-SEM selected 10 indicators for drought risk assessment. Using the selected indicators and the objective weighting methods, this study determined that the drought hazard, vulnerability, response capacity, and risk were highest in GS26 (Ulleung), GS27 (Changwon), GS16 (Cheongsong), and GS28 (Jinju), respectively. The districts with large actual drought damage had high drought risk, indicating that the results of this study were reasonable and useful in the identification of the major impacts and risk of regional drought and may facilitate the decision-making process for selecting drought countermeasures to reduce drought risk.

Cowpea (Vigna unguiculata [L.] Walp.) plants display contrasting sulfur-mediated drought acclimation in greenhouse and field

ABSTRACT Water restriction is a critical environmental condition for plants capable of promoting severe losses in agricultural yield. Our hypothesis was that sulfur (S) supplementation alleviates drought damage for enhanced performance of cowpea cultivars under semiarid conditions. Two parallel experiments were conducted in greenhouse and field, using two cowpea cultivars (Xique-xique and Novaera) subjected to two water regimes (control and drought) and three S levels (S-40, S-80 and S-120 kg ha−1). Drought had a more restrictive impact on cowpea in greenhouse than in field. Drought-stressed plants in greenhouse showed drastic reductions in net photosynthesis, stomatal conductance and dry mass, for both cowpea cultivars as compared to controls. S-80 supplementation in greenhouse and S-120 in field promoted growth recovery of stressed-Novaera plants as related to S-40 stressed ones, exhibiting a performance closer to that of well-irrigated plants. Superior performance of S-supplemented stressed Novaera plants was associated with activation of mechanisms for water retention, likely osmotic adjustment, evidenced by increased water content, stomatal conductance and transpiration. These physiological adjustments allowed plants to maintain elevated net photosynthesis and growth under drought. In conclusion, S supplementation proves effective in mitigating drought damage in Novaera cultivar, offering potential for cultivating cowpea plants in water-scarce environments.