Improve Water Use Research Articles

Improved water use efficiency of vegetation due to carbon fertilization not translating to increased soil moisture in India

Soil moisture (SM) plays a critical role in land–atmosphere interaction. Literature shows that the CO2 fertilization effect (CFE) governs vegetation dynamics and its interactions with the atmosphere. However, the impacts of changing vegetation properties due to CFE, on SM, specifically in India, remains unexplored. Comparing Land-hist (observed CO2 concentration) and Land-cCO2 (constant preindustrial CO2 concentration) simulations with the same meteorological forcings from the Land Use Model Inter-comparison Project (LUMIP), we found that changing vegetation due to CFE impacts SM following two pathways. Enhanced water use efficiency (WUE) due to CFE seeks to ameliorate SM by regulating transpiration. Conversely, elevated CO2 increases leaf area index and plant water use, ultimately leading to a decrease in SM due to the combined impacts of CFE in India. This reduction is most prominent in arid regions, where we observe a decline in SM particularly during dry periods. Our study highlights the need to consider plant physiology in land surface modeling under increased CO2 concentration.

Water use efficiency and canopy temperature response of soybean subjected to deficit irrigation

Deficit irrigation is a key strategy for improving water use efficiency (WUE) under irrigated conditions. However, there is a lack of information regarding the optimal water replacement that have minimal negative effects on soybean productivity. The objective of this study was to determine the water replacement levels associated with insignificant grain yield (GY) losses in soybean crops. A rain shelter experiment was conducted using a randomized complete block design with six replicates. Eight irrigation replacement levels, L120, L100, L90, L80, L70, L60, L50, and L40, were applied, where L100 was the reference treatment that kept soil moisture content along the soil profile under field capacity conditions and all other replacement levels were a fraction of this reference level. Grain yield ranged from 2.2 Mg ha-1 in L40 to 4.4 Mg ha-1 in L100, with a significant GY reduction in irrigation levels below 70%. The average crop water stress index (CWSI) ranged between 0.26 at L120 and 0.66 at L40 irrigation levels. WUE varied significantly only for the extreme irrigation levels studied, with the greatest value at the L40 irrigation level (1.2 kg m-3) and the lowest value at the L120 irrigation level (0.65 kg m-3), whereas for the intermediate irrigation levels from 50 to 100%, the WUE was equal to approximately 1.1 kg m-3. The relationship between CWSI and GY (R2 = 0.85) suggested that the maximum GY occurred at a CWSI of 0.34. In addition, the relationship between CWSI and WUE (R2 = 0.73) showed that as evapotranspiration decreased, crop temperature increased. In conclusion, the implementation of a continuous water deficit in soybeans is feasible for farmers in water-scarce areas, but the minimum value of area productivity must be considered, even though WUE increases under more intensive values of water deficit.

A synoptic review of deficit irrigation methods: sustainable water-saving strategies in vegetable cultivation

ABSTRACT It is elusive and highly challenging to sustain the productivity of vegetable commodities under limited available natural resources and anticipated future climatic scenarios. Amongst available natural resources, water remains the most limiting factor. Present vegetable cultivation practices involve the utilization of excessive quantities of water, thereby leading to the wastage of precious water resources. Therefore, sustainable management of irrigation water is crucial for future vegetable cultivation, as most vegetable crops are vulnerable to water scarcity at different growth stages, which can result in yield and post-harvest quality losses. Adoption of deficit irrigation (DI) is one of the sustainable irrigation water management approaches. DI is a sustainable water-saving approach, as irrigation water is applied in limited or lower quantities than the actual evapotranspiration-based crop water requirement. Strategic application of water at the right time and quantity with the right technique can greatly improve water use efficiency and water productivity. It could also enhance the post-harvest quality with marginal yield loss. Yield losses whatsoever could be compensated by expanding agricultural areas in water-scarce zones by adopting the DI strategy. This review discusses the concept and types of DI and examines its implications for the morpho-physiology and productivity of commercially important vegetable crops.

Mathematical Modeling for Predicting Growth and Yield of Halophyte Hedysarum scoparium in Arid Regions under Variable Irrigation and Soil Amendment Conditions

Growing degree days (GDDs) and leaf area index (LAI) greatly influence the growth and yield of many crops grown in arid regions. Therefore, variation in LAI due to GDD can provide a theoretical basis for predicting crop growth, water consumption, plant development, and yield in arid agriculture via the development of mathematical growth models. This study described the relationship between plant biomass production and variation in LAI due to GDD in arid regions under different types of irrigation (fresh water and saline water) and soils amended with different substances (manure+sandy soil, compost+sandy soil, clay+sandy soil, and sandy soil). Mathematical models for LAI were established for GDDs. In addition, different water quality irrigation techniques were used as independent variables to calculate the LAI of halophytic plants (Hedysarum scoparium) in arid regions under different soil amendment treatments. Furthermore, mathematical models for plant biomass production were developed by using the LAI and GDDs. For this purpose, Logistic, Gaussian, modified Gaussian, and Cubic polynomial models were used. Modified Gaussian and Cubic polynomial models are the best among all developed models, but Cubic polynomial models are more suitable among all developed models because of their simple quadratic equations that can be solved by using the first derivative. It was observed that with increased salt concentration in the irrigation water, the growth of per plant production decreased. However, soil amendments like manure and compost enhance salt tolerance against salt stress and enable plants to sustain their growth. Furthermore, Hedysarum scoparium attains maximum LAI when its GDD is about 1117.5 °C under both irrigation regimes and in all soil amendment treatments. It was concluded that these predicted mathematical models can provide crucial insights for enhancing production in arid regions by using eco-friendly soil amendments to improve water use efficiency across diverse types of water irrigation.

Enhancing Soil Conditions and Maize Yield Efficiency through Rational Conservation Tillage in Aeolian Semi-Arid Regions: A TOPSIS Analysis

Conservation tillage technology possesses substantial potential to enhance agricultural production efficiency and tackle issues such as wind erosion and land degradation in semi-arid regions. The integration of no-tillage and straw mulching technologies in the conventional aeolian semi-arid agricultural zones of western Liaoning, China, has led to notable improvements in crop yield and soil quality. However, a comprehensive assessment of the mechanisms and kinetics involved in soil nutrient variations is yet to be conducted. During a two-year study period, we assessed four tillage systems in the aeolian semi-arid regions of Northern China: no-tillage with full straw mulching (NTFS), no-tillage with half straw mulching (NTHS), no-tillage without straw mulching (NT), and conventional tillage (CT). The investigation focused on examining nutrient conditions, enhancing photosynthetic activity, and increasing maize yield while improving water use efficiency (WUE). Our findings emphasize the beneficial impact of combining no-tillage and straw mulching on enhancing soil water retention, resulting in a notable rise in soil moisture levels during the crucial growth phases of maize. This approach also positively influenced soil nutrient levels, particularly in the 0–20 cm layer, fostering an environment conducive to maize cultivation. In terms of ecological benefits, no-tillage with straw mulching curtailed soil sediment transport and wind erosion, notably at 30–40 cm heights, aiding in the ecological protection of the region. The yield and WUE were substantially higher under NTFS and NTHS than under CT, with NTHS demonstrating the most significant gains in yield (14.5% to 16.6%) and WUE (18.3% to 21.7%) throughout the study period. A TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) analysis confirmed NTHS as the optimal treatment, achieving the highest scores for soil water, nutrient availability, wind erosion control, maize photosynthesis, yield, and WUE, thus emerging as the most effective conservation tillage strategy for sustainable agriculture in aeolian semi-arid regions.

Mechanized No-Tillage Planting with Maize Straw Mulching Improves Potato Yield and Water Use Efficiency in Arid Regions of Northwest China

To explore the yield-increasing mechanism of mechanized potato planting with corn straw mulching, a two-year (2021 and 2022) field experiment was conducted to study the effects of mechanized no-tillage with straw mulching on potato yield and water use efficiency. This experiment included mechanized no-tillage potato planting with corn straw mulch covering (JG), plastic film mulching (HM), and open flat planting (CK). The results showed that mechanical no-tillage with straw mulching significantly affected soil water content in the 0–100 cm soil layer, yield, and water use efficiency (p < 0.05). There was no significant difference in yield between JG and HM, but it was significantly higher than that of CK. The yield of JG was 3.09~12.27% higher than that of CK. The yield increase was mainly achieved by increasing the potato weight per plant (0.697~0.862 **) and the average single potato weight (0.048~0.631). The tuber weight per plant was positively correlated with the plant height at the seedling stage (0.03~0.92 **) and positively correlated with the dry weight of stems and leaves at the tuber expansion stage and starch accumulation stage (0.74 **~0.95 **). It was negatively correlated with the number of branches at the tuber formation stage (−0.33~−0.88 **). Compared with CK, JG could significantly improve the water use efficiency of potatoes and reduce water consumption during the whole growth period of crops. In 2021, JG was 6.5% higher than CK, and HM was 6.88% lower than CK. In 2022, JG and HM increased water use efficiency by 26.17% and 14.50% compared with CK. When HM is applied in heavy soil areas, soil compaction can easily occur, which affects seedling emergence and reduces yield. At the same time, JG has strong adaptability to soil types and good yield stability. It can be seen that JG is a green and efficient mechanized potato cultivation technology suitable for dry farming areas.

Short range shifts in plant physiological responses to induced water stress: Experimental evidence of intraspecific trait variability differentiating neighbouring Mediterranean plant populations

Mediterranean plants are facing increased periods of drought, potentially jeopardizing their survival. Despite the known influence of intraspecific variability on plants’ responses to the environment, most studies focus on differences between species and overlook short distances. Following the observation of three nearby populations of Quercus ilex and Cistus salviifolius inheriting different sets of drought-related functional traits in common garden, we tested if these populations could perform differently under water stress. We observed drought responses on plantlets from both species, measuring key physiological traits such as gas exchanges and spectrometric indexes. Our results show similar responses from populations of C. salviifolius while Q. ilex had high intraspecific variability, with increased drought-resistance in plants hailing from dry provenances, reflected by improved water use efficiency, photosynthetic capacity, and reduced metabolic response to stress. These observations support the idea that, despite the short distances, neighbouring plant populations can adapt differently to drought, changing the way they withstand climate and its changes.

Impact of Using Subsurface Water Retention Technology on Improving Water Use Efficiency of Furrow Irrigation System

Impact of Using Subsurface Water Retention Technology on Improving Water Use Efficiency of Furrow Irrigation System

Thermal imaging from UAS for estimating crop water status in a Merlot vineyard in semi-arid conditions

AbstractThermal remote sensing indicators of crop water status can help to optimize irrigation across time and space. The Crop Water Stress Index (CWSI), calculated from thermal data, has been widely used in irrigation management as it has a proven association with evapotranspiration ratios. However, different approaches can be used to calculate the CWSI. The aim of this study is to identify the most robust method for estimating the CWSI in a commercial Merlot vineyard using high-resolution thermal imaging from Unoccupied Aerial Systems (UAS). To that end, three different methods were used to estimate the CWSI: Jackson’s model (CWSIj), Wet Artificial Reference Surface (WARS) method (CWSIw), and the Bellvert approach (CWSIb). A simpler indicator calculated as the difference between canopy and air temperature (Tc–Ta) was the benchmark to beat. The water status of a vine cultivar with anisohydric behavior (Merlot) in a vineyard in central Spain was assessed for two years with different agroclimatic conditions. Canopy temperature (Tc) was obtained from UAS flights at 9:00 h and 12:00 h solar hour over eight days during the irrigation period (June–August), and from vines under five different irrigation treatments. Stem water potential (SWP), stomatal conductance (gs), and leaf temperature (TL) were recorded at the time of the flights and compared with the thermal indices (CWSIj, CWSIw, CWSIb) and the benchmark indicator (Tc–Ta). Results show that the simpler indicator of water stress, Tc–Ta, performed better at identifying varying levels of crop hydration than CWSIb or CWSIw at 12:00 h. Under conditions of extreme aridity, the latter indices were less accurate than the physically-based CWSIj at 12:00 h, which had the highest correlation with SWP (r = 0.84), followed by the benchmark index Tc–Ta (r = 0.70 at 12:00). Considering the current climatic trends towards aridification, the CWSIj emerges as a useful operational tool, with robust performance across days and times of day. These results are important for irrigation management and could contribute to improving water use efficiency in agriculture.

Optimizing Crop Spatial Structure to Improve Water Use Efficiency and Ecological Sustainability in Inland River Basin

Optimizing Crop Spatial Structure to Improve Water Use Efficiency and Ecological Sustainability in Inland River Basin

Elevated CO2 concentrations contribute to a closer relationship between vegetation growth and water availability in the Northern Hemisphere mid-latitudes

The Northern Hemisphere mid-latitudes, with large human populations and terrestrial carbon sinks, have a high demand for and dependence on water resources. Despite the growing interest in vegetation responses to drought under climate change in this region, our understanding of changes in the relationship between vegetation growth and water availability (referred to as Rvw) remains limited. Here, we aim to explore the Rvw and its drivers in the Northern Hemisphere mid-latitudes between 1982 and 2015. We used the satellite-derived normalized difference vegetation index (NDVI) and the fine-resolution Palmer drought severity index (PDSI) as proxies for vegetation growth and water availability, respectively. The trend analysis results showed that changes in NDVI and PDSI were asynchronous over the past three decades. Moreover, we analyzed the spatiotemporal patterns of the correlation coefficient between NDVI and PDSI. The results indicated that the Rvw was getting closer in more areas over the period, but there were differences across ecosystems. Specifically, most croplands and grasslands were primarily constrained by water deficit, which was getting stronger; however, most forests were primarily constrained by water surplus, which was getting weaker. Furthermore, our random forest regression models indicated that the dominant driver of changes in the NDVI-PDSI correlation was atmospheric carbon dioxide (CO2) in more than 45% of grid cells. In addition, the partial correlation analysis results demonstrated that elevated CO2 concentrations not only boosted vegetation growth through the fertilizer effect but also indirectly enhanced water availability by improving water use efficiency. Overall, this study highlights the important role of atmospheric CO2 in mediating the Rvw under climate change, implying a potential link between vegetation greening and drought risk.

Impacts of droughts and human activities on water quantity and quality: Remote sensing observations of Lake Qadisiyah, Iraq

Water quantity and quality in lakes are closely linked to the compounding effects of climate change and human activities in their catchments, especially for lakes located in semi-arid and arid regions where water resources are scarce. Whilst knowledge gaps exist for these effects in semi-arid and arid region lakes due mainly to the lack of long-term in situ monitoring data. By using satellite remote sensing data, this study firstly investigated the variations of water level, chlorophyll-a concentration (Chl-a) and turbidity in Lake Qadisiyah, Iraq between 2000 and 2019. Results showed that the average water level was 138.3 m in 2000–2019, it decreased clearly in 2001, 2009, 2015 and 2018 with the lowest value of 120 m in July 2015. The mean Chl-a was 6.3 mg/m3 and it showed an overall increasing trend during 2000 and 2019. Turbidity showed extremely high values (>10 NTU) in 2009 and 2017–2018 compared to the mean value of 3.6 NTU in 2000–2019. The boosted regression tree (BRT) was then used to explore the relationship between those variations and El Niño-Southern Oscillation, droughts, meteorological factors and land use land cover changes in the catchment. Results revealed that water level declines were mainly associated with droughts led by La Niña events. Chl-a increase in the lake were mainly explained by built-up area increase and water area decrease in the catchment, with a relative contribution of 29.2 % and 28.6 % respectively. Water area changes in the catchment were the main factor influencing turbidity explaining 55.3 % of the variation. An exception water level decline in 2014–2016 was also observed when there was no drought, which was most likely caused by the cut off of water flow upstream and the release of water from the dam during periods of war. The findings in this study underscored the impacts of climate and human activities on water quantity and quality in semi-arid region lakes. Actions such as improving water use efficiency, establishing water storages, and enhancing cross-border cooperation are therefore recommended to deal with extreme events. Pollution control measures in the catchment are also suggested to prevent water quality deterioration in the lake.

Effect of deficit irrigation and partial rootzone drying on the water consumptive use, growth and yield of faba bean (vicia faba L.) in a gypsiferous soil

Iraq’s farming sector is under increasing pressure to improve water use productivity as a result of the recent drought, environmental concerns regarding sustainable river ecosystems, and government policies on water metering and allocations. To cope with scarce supplies, deficit irrigation, and partial rootzone drying, defined as the application of water below full crop-water requirements, is an important tool to achieve the goal of reducing irrigation water use. It is necessary to develop new irrigation scheduling approaches, not necessarily based on full crop water requirement, but ones designed to ensure the optimal use of allocated water. These two methods of irrigation are one way of maximizing water use efficiency (WUE) for higher yields per unit of irrigation water applied: the crop is exposed to a certain level of water stress either during a particular period or throughout the whole growing season. The expectation is that any yield reduction will be insignificant compared with the benefits gained through diverting the saved water to irrigate other crops. This paper reviews the yield response of the faba bean (Vicia faba L.). The deficit of irrigation on gypsiferous soils is not known. A field experiment was carried out to study the effect of deficit irrigation and partial drying of the root system on the growth and yield of the bean Randomized Complete Blocks (RCBD) design in gypsiferous soil in the fields of the College of Agriculture- Tikrit University, which is located on Latitude 49° 40ʹ 34˝ North and Longitude 40° 38ʹ 43˝ East At an altitude of 129 m above sea level. The study included seven treatments of full irrigation, deficit irrigation, 25, 50 %, and fixed, alternating partial drying. The seeds of the Barcelona variety were sown for the season on 16/10/2021 and harvested on 2/4/2022. The results showed that the full irrigation treatment gave the highest water consumption use of 635 mm, while the alternative partial root drying decreasing 50% gave the lowest water consumption use of 245 mm and gave the highest crop water use efficiency of 2.0 kg m-3. Treatment full irrigation gave the highest seed yield of 5186.3 kg.ha-1, While the 50% deficit irrigation treatment gave the highest dry weight of the root system, which was 25.6 gm.plant-1.

SDG 6 progress analyses in sub-Saharan Africa from 2015–2020: the need for urgent action

This study used data from various international databases to track the progress of SDG 6 target indicators in sub-Saharan Africa (SSA) region between 2015 and 2020. Findings showed that although minimal positive progress was realized in the evaluation period, more than half of SSA residents had no access to safe drinking water services, improved sanitation facilities, hygiene services and safe wastewater treatment. The computed SDG 6 profile index conformed with the trend of indicators as progress of the region to the goal’s realization was rated as medium–low. The trend was further compounded by limited data, preferential access to water and sanitation services to the urban rich and poor monitoring of progress. The analysis also noted that despite these challenges the region was putting concerted efforts to promote transboundary cooperation in water management and had 6% of water stressed resources. The study recommended on the need to revamp water data collection and monitoring efforts to enable decision-making and planning on management actions, use of technology to treat and reuse wastewater as well as device new sources of water, enhanced participation of communities in water projects and improved water use efficiency to steer progress towards SDG 6 realization in SSA region.

Endophyte-Mediated Populus trichocarpa Water Use Efficiency Is Dependent on Time of Day and Plant Water Status

Endophytes are potential partners for improving the resource use efficiency of bioenergy feedstock systems such as short rotation coppice Populus species. Endophytes isolated from members of the Salicaceae family have broad host compatibility and can improve water use efficiency (WUE) through decreases in stomatal conductance. However, the literature is inconsistent with regard to the environmental conditions and temporal patterns of these benefits. This study investigated how endophyte-mediated changes in Populus trichocarpa ‘Nisqually-1’ stomatal conductance and WUE shift with time and scale in response to water deficit stress. Leaf gas exchange and aboveground productivity were used to evaluate the carbon and water balance of greenhouse-grown plants in response to endophyte inoculation and water deficit. Differences in stomatal conductance between control and inoculated plants were more pronounced (39.7% decrease, Welch two-sample t [14.34 adjusted degrees of freedom] = –2.358, P = 0.033) under water deficit conditions in the late morning during a period of higher light intensity. The decrease in stomatal conductance accompanied a substantial increase in intrinsic WUE (iWUE) for water deficit inoculated plants. However, increases in iWUE did not result in improvements in aboveground productivity or shoot biomass WUE for water deficit inoculated plants. This decoupling between iWUE and aboveground productivity may be an indicator of assimilate allocation to microbial metabolism as an additional carbon sink or a shift in carbon allocation toward belowground biomass. Future work should take a whole plant approach that accounts for diurnal patterns in incident irradiance to evaluate the impact of endophyte inoculation on host WUE and stress tolerance.

Evaluation of water resources carrying capacity in China based on entropy weight TOPSIS model

Water resources carrying capacity refers to the ability of the water resources ecosystem to continuously carry the coordination relationship between human society and economy in the normal development process of a country or a region. Its self-sustaining ability, self-regulation and self-development potential often hinder sustainable development in water shortage areas. Research on water resources’ carrying capacity is a meaningful way to support regional water resources security and realize harmonious development of society, economy, and ecological environment. Correct assessment of water carrying capacity and response to government policies will contribute to improved water use and sustainable economic and social development. This study first sorts out the relevant questionnaires of water resources carrying capacity level evaluation, proposes the evaluation indicators of water resources carrying capacity level, collects and standardizes the required data, and calculates the weight of each evaluation index by entropy weight method. Then, it calculates the comprehensive evaluation value of China’s water resources carrying capacity from 2012 to 2022 in the TOPSIS model. The results show that the total afforestation area, total investment in environmental pollution control, and total industrial wastewater discharge are the third most important factors in improving the carrying capacity of water resources. From 2003 to 2010, China’s water resources carrying capacity improved year by year. From 2011 to 2021, China’s water resources carrying capacity remained stable year by year. The continuous adjustment of China’s industrial structure and strengthening environmental pollution control are inevitable measures to improve the carrying capacity of China’s water resources. This study provides a scientific basis for exploring the changing trend of China’s water resources carrying capacity and formulating reasonable optimal allocation of water resources. It also has great significance for promoting China’s water resources’ carrying capacity and sustainable development of the social economy and ecological environment.

Inter-basin water transfers and water rebound effects: The South-North water transfer Project in China

Inter-basin water transfers (IBWTs) aimed at mitigating uneven spatial distribution of water offer the potential to save water through changes in water use efficiency. However, the water rebound effect induced by the improved water use efficiency may offset the water-saving effect of IBWTs. Existing studies failed to explain this complex association between IBWTs and the water rebound effect. A conceptual framework of IBWTs and the water rebound effect is proposed in this study, and the causal association between the two and the possible mechanisms involved are scrutinized in the case of China’s South-North Water Transfer Project (SNWTP). This study argues a causal association between SNWTP and the mitigation of water rebound effects, which is usually associated with the SNWTP’s ability to change the industrial structure and enhance environmental regulation intensity in water-receiving areas. In addition, SNWTP also improves water availability and reduces water use efficiency, thus indirectly mitigating the water rebound effect. Finally, the influence of SNWTP on water rebound tends to vary depending on the economic and demographic differences in water-receiving areas.

Functionality of arbuscular mycorrhizal fungi varies across different growth stages of maize under drought conditions

Physio-biochemical regulations governing crop growth period are pivotal for drought adaptation. Yet, the extent to which functionality of arbuscular mycorrhizal fungi (AM fungi) varies across different stages of maize growth under drought conditions remains uncertain. Therefore, periodic functionality of two different AM fungi i.e., Rhizophagus irregularis SUN16 and Glomus monosporum WUM11 were assessed at jointing, silking, and pre-harvest stages of maize subjected to different soil moisture gradients i.e., well-watered (80% SMC (soil moisture contents)), moderate drought (60% SMC), and severe drought (40% SMC). The study found that AM fungi significantly (p < 0.05) affected various morpho-physiological and biochemical parameters at different growth stages of maize under drought. As the plants matured, AM fungi enhanced root colonization, glomalin contents, and microbial biomass, leading to increased nutrient uptake and antioxidant activity. This boosted AM fungal activity ultimately improved photosynthetic efficiency, evident in increased photosynthetic pigments and photosynthesis. Notably, R. irregularis and G. monosporum improved water use efficiency and mycorrhizal dependency at critical growth stages like silking and pre-harvest, indicating their potential for drought resilience to stabilize yield. The principal component analysis highlighted distinct plant responses to drought across growth stages and AM fungi, emphasizing the importance of early-stage sensitivity. These findings underscore the potential of incorporating AM fungi into agricultural management practices to enhance physiological and biochemical responses, ultimately improving drought tolerance and yield in dryland maize cultivation.

Influence of successive cycles of water stress on tomato production at fruiting stage

Progressive reduction of water supply was imposed during early period (S1) and late period (S2) interceded by a recovery, with a moderate stress for first case and un intensive stress for second case, at fruiting stage of tomato (Lycopersicon esculentum Mill. cv. Rio Grand). The influence of this reduction on fruit production, shoot growth, water content (WC), relative water content (RWC), leaf area (LA), specific leaf weight (SLW), total soluble solids of fruit (T.S.S.) and maturity percentage of fruit were investigated. Repetition of water stress (S1+S2) was obviously reducing the shoot growth, fresh yield, WC, LA and maturity percentage, whereas that was not achieved in dry weight of fruits (FDW), RWC, SLW and T.S.S. Since, a significant difference was founded between the effects of S2 cycle and when that has been preceded by another one S1+S2 on accumulation of dry matter of fruit. Two successive cycles of water stress were doubled of FDW by two times of that registered in control. These results indicate that, during fruiting stage, the effect of gradually exposure of a moderate water stress period, followed by recovery, thereafter by another gradually exposure of un intensive water stress period, contributed to better accumulation of dry matter in fruit by an osmotic adjusting therefore improving water use efficiency, compared to the effect of only one high intensive of water stress applied during the second period. Repetition cycle of water stress may be useful to develop management systems for a reasonable production of tomato and thus reducing the needs of irrigation water in regions facing deficit of water supplies.

Improving Water Use Efficiency, Yield, and Fruit Quality of Crimson Seedless Grapevines under Drought Stress

Drought stress is a group of abiotic stresses that affects plant growth and yield production. A field experiment over two successive seasons (2021–2022 and 2022–2023) in sand soil was conducted to investigate the integration effect of deficit irrigation, soil amendment “hundzsoil”, and the spraying of proline on the water use efficiency (WUE), yield, and fruit quality of 8-year-old Crimson seedless table grapes. Four application rates of soil amendment (0, 2, 4, and 6 kg hundzsoil /vine) were added during the dormancy period, and four irrigation levels at 125, 100, 75, and 60% of the field capacity were applied just before flowering until harvest. Proline at two levels (0 and 500 ppm) was applied as a foliar spray. Parameters such as bud fertility, weight of 100 berries, juice volume, and cluster number were positively affected by irrigation at 75% FC along with applying hundzsoil at 2 and 4 kg/vine under proline spray in both seasons. Irrigation at the 125% FC level with a 6 kg hundzsoil application under proline spray resulted in the highest yield, berries number, cluster length, cluster weight, and total anthocyanin in both seasons. The TSS/acidity ratio was significantly and positively affected by deficit irrigation (60% FC level) under hundzsoil at a rate of 4 kg alongside proline spray. Reducing irrigation to 60% FC without hundzsoil and proline spray negatively affected numerous growth parameters and the yield. However, irrigation at 60% FC alongside 6 kg of hundzsoil and proline showed the highest IWUE in both seasons. Proline spray was a key factor in conserving water used for irrigation. This study recommends using deficit irrigation alongside hundzsoil application under proline spray as an adequate strategy for water use efficiency and improving the yield and fruit quality of Crimson seedless grapevines cultivated in sand soil.