Severe Water Stress Research Articles

Root Development Monitoring under Different Water Supply Levels in Processing Tomato Plants.

Managing crop yields and optimizing water use is a global challenge, as fresh water supply decreases rapidly and demand remains high. Therefore, understanding how plants react to varying water levels is crucial for efficient water usage. This study evaluates how tomato plants adapt to varying water levels (100%, 50% of crop evapotranspiration, and non-irrigated control) over two growing seasons in 2020 and 2021. Root images were captured weekly during an 8-week monitoring period in 2020 and 6 weeks in 2021 using a non-destructive CI-600 in-situ root imager at depths between 10 and 70 cm. Under water stress, plants developed deeper, more extensive root systems to maximize water uptake, consistent with prior research. Root depth and architecture varied with soil depth and the severity of water stress. Year-to-year variations were also found, likely due to changes in irrigation levels and environmental conditions such as temperature. SPAD values were higher under control conditions, especially in the 2021 growing season, suggesting reduced chlorophyll degradation, while no significant differences were observed in chlorophyll fluorescence (Fv/Fm) between treatments, suggesting stable photosynthetic efficiency under varied water stress conditions. These findings contribute to our understanding of root zone optimization and drought-resilient cultivar breeding, contributing to more sustainable agricultural practices.

Root endophyte Piriformospora indica significantly affects mechanisms involved in mitigating drought stress in rice (Oryza sativa)

An experiment was conducted during the summer season of 2020 at College of Agriculture, Kerala Agricultural University, Vellayani to study the potential of a beneficial root endophyte Piriformospora indica Sav. Verma, Aj. Varma, Rexer G. Kost & P. Franken in mitigating drought stress in rice (Oryza sativa L.). The field experiment was undertaken in the lowland paddy fields with sandy clay loam texture in randomized block design. Treatments were Piriformospora indica colonized and non-colonized rice seedlings under 3 irrigation intervals of 30 mm, 35 mm and 40 mm cumulative pan evaporation and 2 irrigation depths of 1.5 cm and 3 cm. Plants colonized with P. indica significantly enhanced the yield attributes and root parameters. This symbiotic association alleviated the negative effects of drought stress by maintaining higher proline content (71.8 μmole/g) and relative leaf water content (74%) irrespective of interval and depth of irrigation. Colonization boosted the uptake of phosphorus and maintained higher chlorophyll stability index (79.20%). Yield attributes of P. indica colonized plants subjected to severe stress, were observed to be equivalent to those of non-colonized plants under moderate stress and association with the endophyte resulted in saving of 30 mm water and could help rice to combat drought stress. Higher phosphorus uptake enhanced the root volume (29.1cm3 ) under severe water stress facilitated improved nutrient uptake (10.6 kg/ ha) from deeper layers of soil for colonized plants compared to the control plants and acted as a mitigating mechanism against drought stress.

The effect of alternate partial root-zone drying and deficit irrigation on the yield, quality, and physiochemical parameters of milled rice

While paddy fields produce a high yield, they also require a large amount of water and produce a significant amount of methane. Therefore, the adoption of water-saving irrigation techniques for rice cultivation is critical. Furrowed rice farming may be a viable alternative to paddy rice cultivation. The objective of the present study was to evaluate the impact of alternate partial root-zone drying irrigation on rice yield, milled rice quality, and cooking quality under furrow rice cultivation. A two-year field trial was conducted on a local rice cultivar, Tarom Hashemi, in 2015 and 2016. Seven water regimes, including three levels of regulated deficit irrigation (RDI), three levels of alternate partial root-zone drying irrigation (APRDI), and conventional flooding irrigation (CFI), were used in this study. In RDI and APRDI treatments, plots were irrigated when soil matric potential had reached −0.1 (RDI1 and APRDI1), −0.3 (RDI3 and APRDI3), and −0.6 bar (RDI6 and APRDI6). RDI1 and APRDI1 treatments produced milled rice yield similar to the CFI, while irrigation water productivity (IWP) was significantly higher by 22.9% and 45.7%, respectively. Regardless of the soil water potential, the IWP in APRDI treatments was 16% higher than that of RDI treatments. Severe water stress (RDI6 and APRDI6) caused a marked increase in amylose content and alkali spreading value of milled rice resulting in improved cooking quality. Nitrogen uptake in APRDI treatments was 2% higher than that of RDI treatments. On average, methane emission per milled grain yield declined by 77.9% and 78.7% in RDI and APRDI treatments, respectively. Our data indicate that the expensive and laborious practice of puddling can be avoided to increase water productivity and improve rice quality without sacrificing yield. The results also show that furrow rice cultivation could significantly reduce the methane emission contribution of rice production.

Addressing non-revenue water as a global problem and its interlinkages with sustainable development goals

Abstract By 2050, over 40% of the global population could face severe water stress. The 2030 Agenda explicitly integrates water resources, supply, and sanitation, emphasizing sustainability for present and future generations. Non-revenue water (NRW) creates a barrier to sustainability through energy, water loss, and money not collected through water bills. However, NRW is well recognized by water service providers, and a comprehensive solution is lacking. Addressing NRW is vital to sustainable operations and achieving the Sustainable Development Goals (SDGs). This desk literature review investigates NRW's links with SDGs, highlighting global and local impacts, flameworking interconnections, and revealing economic, social, and environmental consequences. The study revealed that NRW not only aligns with various SDGs, particularly SDG 6 and SDG 13, but also has synergies with other goals related to energy and sustainable consumption. Reducing NRW can achieve more sustainable and resilient water systems, and contribute to the broader SDG. The cost of NRW extends beyond the financial implications for water utilities. It also encompasses the economic impacts on industries and businesses, which impacts exceeded water productivity, increased operational costs, and economic development constraints.

Comparison of physiological and biochemical responses of local and commercial tomato varieties under water stress and rehydration

Water scarcity presents an increasingly urgent challenge with global implications for the production of irrigated vegetables. Among these crops, tomatoes stand out as one of the most widely cultivated. Given their vulnerability to water stress, it is crucial to ensure efficient and sustainable water management for tomato irrigation. This study aims to compare physiological and biochemical parameters among three local and three commercial resilient tomato varieties in response to water stress and rehydration. We subjected tomato plants to either two brief periods of water stress (WE1) or one extended period of water stress (WE2), followed by rehydration. Our results did not reveal significant differences in the response to water stress among the varieties, which could be attributed to their respective origins. Following rehydration, the plants quickly returned to their normal physiological values. An exploration of oxidative stress markers revealed that oxidative damage occurred solely during the second episode of water stress in WE1 plants, or towards the conclusion of the prolonged water stress period in WE2 plants. However, after rehydration, tomato plants returned to normal oxidative parameters values, indicating the absence of irreversible damage. Although the severe water stress did not compromise the viability of the plants, all treatments and varieties exhibited a predictable and substantial growth inhibition. In conclusion, the different tomato varieties studied exhibited similar responses to water stress, primarily characterized by the inhibition of gas exchange processes and heightened oxidative stress. Nonetheless, none of the plants suffered irreversible damage from this stress.

Drought-tolerant lines of Physalis angulata L. improved growth, yield, and water use efficiency in drylands

Cutleaf groundcherry (<em>Physalis angulata</em> L.) has the potential to be developed in various areas, including dryland. Information on drought-tolerant varieties, lines, or genotypes is needed for the development of cutleaf groundcherry in dryland. Selecting drought-tolerant lines is an alternative for alleviating yield loss potency caused by water shortages. A pot experiment that aimed to investigate the response of cutleaf groundcherry lines to a different level of water deficit, expressed in field capacity (FC), was run in two factors of factorial randomized block design. Each line (PA-01, PA-03, PA-05, PA-08) was set up in water deficit treatment (100, 80, 60, 40, and 20% FC). The result showed that vegetative growth and fruit production, such as fruit number and weight, mainly decreased at 60 or 40 % FC. In contrast, TSS increased at a higher water deficit which was in line with total flavonoid content, even inconsistently. PA-03 and PA-08 experienced a reduction in fruit weight at 40% FC, whereas other lines occurred at 60% FC. Water use efficiency (WUE) increased under severe water stress. Compared to other lines, PA-03 and PA-08 exhibit higher WUE at 60% FC. In conclusion, PA-03 and PA-08 lines were tolerant of water deficit.

Deciphering the morpho-physiological and biochemical responses in Lablab purpureus (L.), Sweet, seedlings to water stress

Drought is a major crop productivity-limiting factor, which adversely affects growth and yield worldwide. Lablab (Lablab pupureus [L.] Sweet), is better adapted to withstand drought stress, however, characterization of lablab in Kenya has not been undertaken and there is limited knowledge on plant response to drought stress. Ten lablab genotypes were evaluated under greenhouse to determine the morpho-physiological and biochemical response at the seedling stage. The study revealed significant differential responses among lablab genotypes to water stress. The interaction between the water stress and the genotypes significantly affected the evaluated traits. Genotypes D1 and D6 showed significantly increased and superior morphological adaptation, respectively, indicating enhanced adaptation for tolerance to water stress. Significant variations of ascorbate peroxidase, guaiacol peroxidase and catalase activities were detected during the experimental period. The plants exhibited varying non-enzymatic antioxidants and osmolytes with an increase in proline, total phenol and water-soluble carbohydrates and a decline in free amino acids and water-soluble proteins under severe water stress. Genotype D10 recorded high antioxidant enzymatic activity and water-soluble carbohydrates, whereas D1 accumulated more proline and proteins, indicating better adaptation in scavenging reactive oxygen species to prevent membrane damage. The higher photosynthetic efficiency of seedlings of genotype D1 and superior morphological adaptation of D6 indicated better agronomic adaptation to severe water stress and could be utilized in plant breeding programmes for tolerance to drought.

Biochemical and physiological mechanisms allowing olive trees to survive and produce under water stress conditions

The beneficial properties of olive (Olea europaea L.) edible fruits and their oil play an important part in our diet. Severe summer conditions, including low rainfall, excessive heat load and high daily irradiance, characterize arid and semiarid regions where olive is produced. Although it is highly aggravated by other stresses, water stress is usually the most critical during summer-time. Under severe water stress conditions, a cultivar of any olive tree needs specific biochemical and physiological mechanisms in order to survive and be productive. It is well-known that these water stress resistance mechanisms generally act simultaneously. Nevertheless, water stress adaptability not only integrates the water stress resistance concept (i.e., escape, avoidance and/or tolerance to water stress) but also the recovery capacity. All of them play a major role in plants’ growth and survival, especially when plants are continuously exposed to repeated events of water stress and adequate water levels during their lifetime. Water stress, heat and high irradiance, especially in association with each other, also damage plant functions. As a result, different resistance mechanisms are adopted by plants. This review summarizes each of these mechanisms.

Threshold Values of Plant Water Status for Scheduling Deficit Irrigation in Early Apricot Trees

Irrigated agriculture is facing a serious problem of water scarcity, which could be mitigated by optimizing the application of regulated deficit irrigation (RDI) strategies. For this reason, the aim of our study was to determine irrigation thresholds based on direct water status indicators of apricot trees under RDI to maximize water productivity. Three treatments were tested: (i) Control (CTL), irrigated at 100% of the crop evapotranspiration (ETc) during the entire crop cycle; (ii) RDI1, irrigated as CTL, except during fruit growth stages I–II when irrigation was reduced by 20% of CTL, and during late post-harvest, with an irrigation threshold of a moderate water stress of −1.5 MPa of stem water potential (Ψs); and (iii) RDI2, irrigated as RDI1, but during late post-harvest using a severe water stress threshold of −2.0 MPa of Ψs. As the irrigation scheduling of RDI1 and RDI2 did not affect yield and fruit quality, the crop water productivity was increased by 13.2 and 25.6%, respectively. This corresponded to 1124 and 2133 m3 ha−1 of water saved for RDI1 and RDI2. A water stress integral of 30.2 MPa day during post-harvest could be considered optimal since when 41 MPa day was accumulated, vegetative growth was reduced by 35%. The non-sensitive periods to water deficit were delimited by the accumulation of growing degree days (GDD) from full bloom, the end of fruit growth stages I–II corresponded to an accumulation of 640 °C GDD, and the beginning of the late post-harvest to an accumulation of 1840 °C GDD.

Modulating the antioxidant defense systems and nutrients content by proline for higher yielding of wheat under water deficit

Numerous plant metabolites, especially amino acids, are accumulated as a result of stress. These amino acids are crucial for plant metabolism and development and have historically been viewed as the building blocks of proteins. Several studies suggested that there is a link between proline buildup and exposure plants to stress. Proline performs important functions under stress in addition to be a great osmolyte, antioxidant enzyme, acts as an antioxidant defense and signaling molecules. Two field trials were during two successive winter seasons (2020/2021 and 2021/2022). The effects of proline foliar application (0, 100, 200, 300 and 400 mg L−1) and irrigation water levels (irrigation by 100, 80 and 60% of crop water requirements, CWR, CWR100, CWR80 and CWR60, respectively) on plant pigments, antioxidants activity, yield traits and nutrient contents of wheat were assessed. The experiment was designed in a split-plot involving 4 replicates. Drought stress (CWR80 and CWR60) led to reductions in photosynthetic pigments, and yield components. Under severe water stress (CWR60), proline 200 and 300 mg L−1 recorded the highest values of chlorophyll a, chlorophyll b, and total pigments. Application of proline 300 mg L−1 was the potent practice for enhancing the antioxidant activity% (DPPH radical scavenging) and phenols content under CWR100 and CWR80. Indole acetic acid (IAA) possessed the maximum values with proline 200 mg L−1 under all irrigation patterns. Under severe deficit water (CWR60), without proline spraying (for super oxide dismutase), 200, 300 or 400 mg L−1 proline (for peroxidase) and 200 or 400 mg L−1 proline (for polyphenol oxidase) recorded the highest values. Spraying proline 300 mg L−1 achieved the highest values of grain number spike−1, weight of 1000 grains and grain yield ha−1 under different irrigation regimes. In conclusion, proline is considered a good mitigator for drought stress, due to it increased wheat plant tolerance to water deficiency throughout improving plant physiology and consequently yields quantity and quality. The most efficient concentrations of proline for coping the adverse impact of drought were 200 and 300 mg L−1.

Water scarcity risk through trade of the Yellow River Basin in China

Water scarcity poses economic risks and affects the quality of national and regional development. The risk of local water scarcity can be conveyed to downstream economies through interregional trade for potential economic losses. However, most previous water scarcity studies focused on the availability of adequate freshwater supplies, ignoring the economic losses associated with inadequate water quality. With the aggravation of water pollution, water scarcity caused by inadequate water quality is exacerbated. This study incorporates water quality and quantity into local water scarcity risk assessments, revealing the virtual water scarcity risks and transmission pathways of the cities and sectors in the Yellow River Basin (YRB) in China. The results show that the number of cities with severe water stress increases from 13 to 53 when water quality is considered. Virtual water scarcity risks transfer from upstream cities to downstream cities in Henan and Shandong Provinces, and high-risk cities in Henan can be identified by considering water quality. Key transmission pathways for intersectoral transfer are identified. This study validates the significance of considering water quality factors in water scarcity risk assessments and provides a perspective for policy decisions to mitigate water scarcity and thus ensure water security in the YRB.

Effect of Drought Stress on Growth of Soybean under Seedling Stage

The present study was conducted during September-October, 2022 at Greenhouse facility of Experimental Farm, Faculty of Agriculture Sciences, Mandsaur University, Mandsaur, Madhya Pradesh, India to identify drought tolerant genotypes. Total sixty genotypes were sown on dated 02/09/2022 by using polythene bags in completely randomized block design with four different water regimes and two replications in each set during month of September, 2022. Data were recorded for root-shoot parameters and relative leaf water content. Mean performance of root length showed that among 60 genotypes, thirty genotypes showed increased tap roots under severe water deficit conditions (0%). Under sever water stress condition (0%) highest root length was recorded of genotypes NRC138 (20.5 cm) followed by GW251 (18.15 cm) and RSC1107 (17.2 cm) respectively while lowest root length was noted in accession GW312 (3.4 cm) followed by NRC37 (5 cm) and NRC 142 (5.15 cm) respectively. Under0% water stress highest relative leaf water content was observed in genotype JS2034 (97.16%) followed by GW10 (93.47%) and GW159 (89.18%) whereas lowest was found in GW28 (20.96%) followed by GW100 (26.31%) and AGS25 (26.66%). On basis of mean data of root length, relative leaf water content, root shoot ratio by length and visual observation of plants, 11 genotypes were identified as drought tolerant and 19 genotypes were identified as medium tolerant. The identified drought tolerant genotypes may be used as water stress tolerant genotypes in future for improvement of crop in relation to drought tolerance.

Enhancing drought resistance in Pogostemon cablin (Blanco) Benth. through overexpression of ACC deaminase gene using thin cell layer regeneration system.

Pogostemon cablin cultivation faces massive constraints because of its susceptability to drought stress that reduces patchouli propagation and oil yield. The present study has achieved an efficient and rapid direct regeneration system for the transgenic production of P. cablin using Agrobacterium-mediated genetic transformation. To establish an efficient regeneration protocol for fast in-vitro multiplication of patchouli plants, leaf, petiole, and transverse thin cell layer (tTCL) explants were used and inoculated on an MS medium supplemented with different combinations of phytohormones. A comparative study showed a maximum regeneration frequency of 93.30 ± 0.56% per explant was obtained from leaf segments on optimal MS medium fortified with 0.2mg/L BAP and 0.1mg/L NAA. Leaf and petiole explants took 25-35 days to regenerate while tTCL section showed regeneration in just 15-20 days on the same medium. Subsequently, productive genetic transformation protocol OD600 0.6, AS 200µM, 30mg/L kanamycin, and infection time 5 min. was standardized and best-suited explants were infected at optimum conditions from the Agrobacterium tumefaciens (LBA 4404) strain harboring ACC deaminase to generate transgenic P. cablin Benth. (CIM-Samarth) plants. The investigation suggested that the optimized protocol provides a maximum transformation frequency of 42 ± 1.9% in 15-20 days from tTCL. The transgenic plants were shifted to the greenhouse with a 52.0 ± 0.8% survival frequency. A molecular docking study confirmed significant binding affinity of ligand ACC with ACC deaminase at the catalytic site, and ligand interactions showed four H-bonds at the binding pocket with amino acids Cys-196, Val-198, Thr-199, and Gly-200 that validate gene relative expression in transgenic plants. Among all transgenic acclimatized greenhouse-grown patchouli plants, line PT4 showed improved drought resistance under severe water stress as its RWC was 71.7 ± 2.3% to 75.7 ± 2.1% which is greater than the RWC of the control plant, 58.30 ± 0.21%. Analysis of the other physiological indicators, H2O2, chlorophyll content, and ROS result support drought resistance ability. Our study concluded that the first report on P. cablin, tTCL direct regeneration, and standardized transformation protocol created a new opportunity for genetic manipulation to achieve drought-resistant patchouli plants for cultivation in all seasons at the commercial level.

Farmers’ perceptions of severe climate risks and adaptation interventions in indigenous communities in northern Ghana

Perceptions of climate change are widely studied and documented. However, understandings of conceptions and experiences of severe climate risks in indigenous farming communities are insufficient. This research respond to that knowledge gap with evidence from selected indigenous farming communities in northern Ghana through a mixed-method approach. Results from the empirical data show that farmers perceive severe climate risk to mean livelihood disruption throughout the season, unproductive farmlands, ineffective adaptation and inability to break even. The logistic regression estimates show that gender, marital status, livelihood activity and ecological zone are all influential factors that are likely to predict farmers’ perceptions of severe climate risk. Farmers in northern Ghana experience severe physical climate risks such as extreme droughts, extreme temperatures, severe heatwaves, frequent floods and severe water stress. To mitigate severe physical climate risks and disasters, individual farmers implement indigenous adaptation strategies such as livelihood diversification, construction of hand-dug wells in farms, migration, building of mounds or ridges, and early marriage of young girls. Collectively, farming communities culturally utilize animal sacrifices and spiritual incantations to invoke rains to address prolonged droughts. Understanding severe climate risks and their determinants will provide good policy guidelines for early warning systems to sustainably improve livelihood and food security in resource-constrained communities.

Physiological characterization of Vitis hybrid cv Merlot Khorus under two different water regimes in northeastern Italy

Fungus–resistant varieties are gathering attention all over viticultural areas owing to their contribution to sustainable management. Sustainable viticulture implies lower inputs in terms of pesticides and water. However, investigations on the physiological behavior of fungus–resistant varieties under drought stress have been seldom conducted so far. Under climate change conditions, evaluating precise water use is particularly important to set up proper irrigation. In this study, a two-year experiment was imposed to characterize the physiological behavior of the fungus–resistant variety Merlot Khorus under two contrasting water regimes (full irrigation, WW; water deficit, WD). Berry weight and grape quality in the two treatments was also compared to evaluate the feasibility of adopting deficit irrigation strategies in the region. The study was conducted in the Friuli Venezia Giulia region (Italy). The measured values of stem water potential (Ψstem) did not highlight any severe water stress (> -1.15 MPa) in WD. However, gs and AN decreased to values typical of drought–stressed vines. Concurrently, the experiment assessed that the calculated Kcb of Merlot Khorus in northeast Italy is far different from what has been suggested by standard methodologies and the literature. The grapes under deficit irrigation showed reduced berry weight, while basic maturation parameters and anthocyanins were improved. Overall, the study indicated that Merlot Khorus appears to be a genotype suitable for dry farming or deficit irrigation management in northeastern Italy. Therefore, the results may help winegrowers to improve irrigation strategies.

Quantifying water productivity and nitrogen uptake of maize under water and nitrogen stress in arid Northwest China

Water and nitrogen (N) are critical determinants of crop water productivity (WP) and N uptake (Nuptake), and are also key factors in crop modelling. Through a two-year field experiment with three irrigation levels (full irrigation (W1), moderate water stress (W0.75), and severe water stress (W0.5)), three N application rates (150, 75, and 0 kg N ha−1, i.e., N150, N75, and N0) and three replications for each treatment in Northwest China, we quantified the effects of water and N stress on the growth, yield, and water and N use efficiency (WP and NUE) of hybrid seed maize (Zea mays L. cv. Tianruifeng). Furthermore, nonlinear dynamic water productivity (WP) models and water (ET)-based Nuptake models were developed. The results showed that water stress had a larger impact than N stress on the growth and yield of maize, with water stress reducing yield (Y), final aboveground biomass (B), and N uptake by 36.5%, 15.4%, and 25.7% on average, respectively, and N stress decreasing them by 18.7%, 12.3%, and 13.6%, respectively. Biomass-based water productivity (WPB-ET) and yield-based water productivity (WPY-ET) at the end of the growth period responded differently to water stress but similarly to N stress because of a higher decrease of harvest index (HI) under water stress than under N stress. Specifically, WPY-ET decreased significantly while WPB-ET kept relatively stable as water stress increased. The variation of the measured WP during the growth period presented a single peak trend. The Logistic, Sigmoid, and Linear models showed similar high accuracy for quantifying the relationship between evapotranspiration accumulation and biomass growth. However, the derived WP values from the nonlinear dynamic models were more in line with the single peak variation of the measured WP during the growth period, with the agreement index (d) improved from 0.21 to 0.65–0.75 in comparison to the Linear model. The developed ET-based N accumulation models can quantify N uptake through evapotranspiration. The results can contribute to improving the accuracy of crop modelling under drought stress conditions, and the design of irrigation and N management in arid and semi-arid regions.

Role of ACC deaminase-producing rhizobacteria in alleviation of water stress in watermelon

Owing to the increased global warming, drought severity has increased in many regions, threatening food security, especially in arid and semi-arid areas. Therefore, it is imperative to mitigate the impact of drought on plants in water-stressed areas. The utilization of plant-growth-promoting rhizobacteria (PGPRs) serves as an environmentally friendly approach to enhance the resilience of plants exposed to abiotic stress, specifically drought. This research focuses on examining the effects of 35 PGPR isolates, possessing significant ACC (1-aminocyclopropane-1-carboxylic acid) deaminase activity, which were obtained from diverse plant-rhizosphere soil samples encompassing approximately 17,000 km2 of semi-arid regions. The investigation was conducted on watermelon plants experiencing varying degrees of water stress (30% and 60% water stress). An increase in water stress exerted a detrimental effect on agro-morphological parameters, such as biomass (root + shoot), leaf number, and leaf area of non-inoculated plants. PGPRs stimulated plant growth and increased water use efficiency, especially under severe water-stress (60% water stress) conditions compared to non inoculated plants (control). Furthermore, some PGPRs such as B7, B22, B26 and B28 supported carotenoid synthesis, which plays an important role in photosynthesis, whereas some alleviated the effect of water stress in watermelon plants by stimulating the antioxidant defense system. The outcomes of principal component, where the data were collectively assessed, demonstrated the superior efficacy of certain PGPRs. Specifically, under water-stress conditions, PGPR isolates B31, B32, and B35 exhibited significant growth-promoting effects on watermelon. Additionally, isolates B13 and B15 demonstrated the activation of antioxidant defense mechanisms, including proline, catalase, and peroxidase. PGPRs showed considerable results on the agro-morphological, physiological, and biochemical properties of watermelon under 60% water-stress conditions compared with those under 30% water stress. In conclusion, PGPRs promoted growth and alleviated severe water stress in watermelon plants compared to their control. The results of this study elucidate PGPR-triggered response mechanisms in water-stressed watermelon plants.

Groundwater and pore water inputs to the Bay of Bengal supported by geochemical tracers: Example from Tamil Nadu and Pondicherry, East Coast of India

Submarine groundwater discharge (SGD) and Saline water intrusion (SWI) are the two major processes that influence coastal aquifers resulting in severe water stress. It is essential to characterize groundwater dynamics and discriminate geochemical characterization to understand both approaches. The present study investigates the zones influenced by SGD and SWI along the coastal aquifers of Tamil Nadu and Pondicherry. Pore water (PW) and groundwater (GW) samples were collected during the monsoon season at low tide and analyzed for major ions adopting standard procedures. Hydrogeochemical characterization of water samples revealed by the piper, ionic ratio, ionic delta (Δmi), and seawater fraction (fSea) plots suggest that the PW samples, irrespective of location and GW samples in specific areas, were attributed to SWI, while the remaining samples suggested SGD. The average chloride-attributed SGD flux calculated for PW was 23.45 × 10−7 L cm−2 S−1 and for GW, 0.58 × 10−7 L cm−S−1. Higher fluxes observed in PW suggest seawater recirculation as the primary mechanism, and GW samples were found to be influenced by fresh, recirculated, and saline intrusions. Overall, the northern parts of the study region were influenced by freshwater discharge. However, the central and southern parts of the study regions were influenced by mixed RSGD and SWI water types. The present work suggests locations influenced by fresh, recirculated, and saline water zones that can benefit the stakeholders in planning strategies to identify proper aquifer recharge and suggest ideal pumping scenarios to sustain groundwater resources.

Assessing Climate-Driven Salinity Intrusion through Water Accounting: A Case Study in Ben Tre Province for More Sustainable Water Management Plans

This scientific paper delves into sustainable water management strategies for Ben Tre Province of the Vietnamese Mekong Delta (VMD) in light of water-infrastructure plans that have been impacted by climate change-induced salinity intrusion. Specifically, we aim to mitigate the effects of salinity intrusion for the province while promoting long-term environmental sustainability. In doing so, a water accounting framework was applied, mostly based on the MIKE11 hydrodynamic modeling and water balance calculations, to determine current and future water stress issues based on two main scenarios of extreme drought year 2016 (baseline) and the future year 2030 under climate change for a medium-low emission scenario (RCP4.5). The study found that salinity intrusion significantly causes severe water stress in the future year 2030 compared to the baseline year 2016, while the existing water management methods are relatively inadequate to control salinity intrusion, leading to over 57% of the area affected by medium to critical water stress levels, although it will go along with planned water infrastructures. Additionally, a system of triple rice cropping converted two rice cropping and upland cropping with 40% water demand cutoff was found to be the most suitable measure for 2030. Particularly, water-saving and water demand reduction should be incorporated into infrastructural planning for sustainable water management. Our study provides valuable insights for policymakers and stakeholders, not only for the province and the VMD, but also other regions facing similar challenges.

Food demand displaced by global refugee migration influences water use in already water stressed countries

Millions of people displaced by conflicts have found refuge in water-scarce countries, where their perceived effect on water availability has shaped local water security discourses. Using an annual global data set, we explain the effects of refugee migrations on the host countries’ water stress through the food demand displaced by refugees and the water necessary to produce that food. The water footprint of refugee displacement increased by nearly 75% globally between 2005 and 2016. Although minimal in most countries, implications can be severe in countries already facing severe water stress. For example, refugees may have contributed up to 75 percentage points to water stress in Jordan. While water considerations should not, alone, determine trade and migration policy, we find that small changes to current international food supply flows and refugee resettlement procedures can potentially ease the effect of refugee displacement on water stress in water-vulnerable countries.