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Limitations of water and nitrogen in soil usually restrict plant growth. The objective of this study was to evaluate the effects of different amounts of supplemental irrigation at different growth stages and application of different rates of nitrogen fertilizer on grain yield and water productivity of wheat cultivars. A field experiment was conducted in the agricultural research station of Shahrekord University, Iran, for 2 years. The experiment had a split-split plot design with 3 replications. Five irrigation treatments occupied the main plots, two wheat cultivars were the sub-plots, and three levels of nitrogen were allocated to the sub-subplots. Seed yield and water productivity increased with the total amount of water available to plants. Water productivity increased linearly with increasing additional irrigation from the jointing stage to the seed filling stage, in both years. However, the rate of grain yield and water productivity in irrigation treatment at the jointing stage was greater than the other irrigation treatments. Both wheat varieties showed positive response to supplemental irrigation treatments and nitrogen fertilizer, but the rate of grain yield and water productivity was greater in Azar2 cultivar. Additional nitrogen fertilizers also increased seed yield and water productivity in bothyears. Generally, the combination of supplemental irrigation at jointing stage and application of 100 kg nitrogen ha^-1 have important roles in the improvement of seed yield and water productivity of Sardari wheat cultivarunder semi arid region.

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Continuing agricultural expansion and urban development in Saudi Arabia, (located in an arid climate), together with an increased demands for more water supplies, calls for more efficient irrigation practices, and an increase in Crop Water Productivity (CWP). Throughout the present study, a deficit irrigation system was investigated for its impact on soil salinity, crop response factor (Ky), CWP, and a crop, namely cucumber’s (Cucumis sativus L.) yield. Cucumber seeds were planted in a greenhouse equipped with drip irrigation system. The crop evapotranspiration (ETc) was assessed through Pan Evaporation method (PE) and estimation based upon Penman-Monteith equation (PM). The results revealed good agreement between PE and PM ETc. The irrigation treatments consisted of four levels of ETc (40, 60, 80, and 100% of ETc) in addition to the traditional one as practiced by local farmers. At the 60 and 80% ETc treatments, the deficit irrigation was tested at different growth stages (Initial, developmental, middle, and late stages of crop growth). Each of the treatments was carried out in three replicates. The results showed that soil salinity in general increased with decreasing level of applied water. The crop cucumber could tolerate shortage of water during the middle season growth stage, when the Ky values ranged between 0.57 and 0.76. The level of water used up in 100% ETc treatment was much lower than that in the traditional drip irrigation as practiced by farmers. In other words, the CWP values increased with water consumption being decreased. The results also indicated that the highest values for CWP were found for the most stressed treatment of 40% ETc, while on the other hand the overall crop productivity had decreased.

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The effects of grafting greenhouse tomato cultivars (Durinta and Valouro F1) onto three tomato rootstocks (Beaufort, Maxifort, and Spirit) under different irrigation regimes (50, 75, and 100% crop evapotranspiration [ETc]) were studied by evaluating the vegetative growth, proline, chlorophyll, and mineral content of the leaves as well as yield productivity, total yield water use efficiency (TYWUE), and yield response factor (Ky). Plant height, stem diameter, leaf area, and total yield decreased, whereas proline and TYWUE increased, with increasing water stress. Durinta showed more vigorous growth than Valouro. Plant growth, proline, Ca+2 and K+ concentrations, yield, and TYWUE were higher in grafted plants than in non-grafted plants. Negative effect of high water stress (50% ETc) was evident in the non-grafted plants, particularly in Valouro. A positive effect of grafting was observed when Beaufort was used as the rootstock. Durinta grafted onto Beaufort (DB) under moderate watering regime (75% ETc) exhibited water savings (25%) and higher yield (21.55–30.81%) and TYWUE (55.06–55.54%) than fully irrigated (100% ETc) control (non-grafted Durinta). Ky was lower in Durinta (1) than in Valouro (1.2), indicating lower tolerance of Valouro to water stress. Grafted DB showed higher tolerance to water stress (Ky = 0.5) than other combinations. The results indicated that grafting could alleviate some of the negative effects of water limitation on greenhouse tomato plants.

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Water is considered as the most important component, but a limiting input, for agricultural production in Iran. In the context of water resources management, due to the limited availability of water and high cost of supplying it to the users, improvement of water use productivity has been regarded as one of the most appropriate approaches to manage water demand. Various tools have been applied for water management policy in the context of preventing high levels of water deficit. In the present study, different policy scenarios related to water supply management are assessed. These include estimation of the impacts of each policy scenario on physical and economic productivity indices and employment, using positive mathematical programming methods and maximum entropy. This methodology was applied to water use in the Qazvin Plain, Iran. Results suggested that application of these policy scenarios not only decreased water consumption but also generated desirable social and economic effects. Results of the ranking showed that the policy of imposing tax on input generated the best results for the study area. However, it is admitted that selection of the best policy scenario is dependent on the weight that policy makers would select for various indicators.
 

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 To remain viable in facing with increasing costs, farmers need to increase irrigation Water Productivity (WP) and save Virtual Water (VW). To evaluate the WP and VW for five barley cultivars (Reyhan, Nimrooz, Valfajr, Zehak, and Yusof) under different irrigation regimes [well-watered (100% Field Capacity; FC), mild water stress (75% FC), severe water stress (50% FC), and extremely severe water stress (25% FC)], a two-year field experiment was laid out in Darab, Fars Province, Iran, during 2014 and 2015 growing seasons. Results showed that change in moisture stress from well-watered to extremely severe water stress, was associated with a significant increase in WP and Economic Water Productivity (EWP) for straw and biological yield. A positive linear relationship was found between grain yield and VW, and the lowest VW was found in the range of 3,314 to 3,451 kg ha^-1 of grain yield. Interestingly, for all irrigation regimes, Zehak and Yusof cultivars had greater WP for the grain yield. Furthermore, VW for biological yield of Yusof cultivar sharply decreased from 0.410 m³ kg^-1 in well-watered treatment to 0.164 m³ kg^-1 under extremely water stress conditions in both years. Comparison of Zehak and Yusof cultivars with Reyhan, Nimrooz and Valfajr showed that under water stress conditions, the first two cultivars showed significantly lower VW for the grain yield than the other cultivars. Indeed, Yusof and Zehak cultivars showed the lowest Economic Virtual Water (EVW), which was in the range of 0.054 to 0.091 m³ 1,000 Rials^-1, under extremely water stress conditions. Thus, to achieve optimum EWP and EVW and attaining stable yields under semi-arid conditions, suitable barley cultivars such as Zehak and Yusof could be irrigated with less water (i.e. 25 to 50% FC).

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Deficiency of potable water has created many problems for human and human society, Therefore, The production of fresh water from saline water is an important issue. One of the method of production fresh water from saline water is the use of solar stills. This paper is the numerical simulation of the conventional solar stills with setting Rectangular, Triangular, Wavy barriers on the left and right walls inside the solar still. Setting barriers causes a change in the pattern of humid airflow in the solar still that it affect water productivity and convective heat transfer rate. Also, changes in the size and number of barriers cause changes it will be in the result. The continuity, momentum, energy and concentration equations are discretized by finite volume method and the results are presented as flow function and concentration and temperature contours. The simulation results show that setting wavy barriers with A=0.01(m) and N=2 at left wall and A=0.075(m) and N=5 at right wall water productivity and convective heat transfer rate can be increased by about 31% and 31.34%.

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With the increasing world population, global warming, and climate change, water scarcity significantly limits water use in crop production. Therefore, timely and accurate determination of water stress is very important for the correct and effective management of existing water resources and minimizing harmful effects on crop production. Two years of experiments were conducted in the water-limited region in Türkiye to investigate the possible use of the Crop Water Stress Index (CWSI) as a remote sensing technology in sugar beet irrigation scheduling. Four different Irrigation levels (I₅₀: 50% deficit, I₇₅: 25% deficit, I₁₀₀: full irrigation, and I₁₂₅: 25% excess irrigation) were applied to sugar beet by drip irrigation system. The amount of applied irrigation water and crop evapotranspiration varied between 238-540 and 350-580 mm in 2021, and between 324-807 and 502-829 mm in 2022. In both years, the highest beed yields were obtained from I₁₀₀ treatments (83 and 130 t ha^-1) and the lowest from I₅₀ treatments (66.7 and 67.4 t ha^-1). Water Productivity (WP) and Irrigation Water Productivity (IWP) in both years decreased significantly by excessive irrigation. CWSI values ranged between 0.16-0.98 in 2021 and between 0.02-0.71 in 2022. CWSI was significantly related to yield and Leaf Area Index (LAI). According to the results, CWSI could be used successfully in sugar beet irrigation scheduling and yield estimation.

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In arid and semi-arid regions, inadequate rainfall necessitates supplemental irrigation to meet crop water requirements. Selecting the appropriate method is crucial for success. A two-years field experiment was conducted in Kharameh Region, Iran, to investigate the effect of different supplemental irrigation methods on fig tree yield, physiological response, and water productivity. Three irrigation methods including flood irrigation, subsurface drip irrigation, micro jet irrigation, and no supplemental irrigation (control) were applied as four treatments in five replications. Results showed that subsurface and micro jet irrigation significantly increased leaves width by 18.2%, shoot length by 27%, and shoot diameter by 13%. Micro jet irrigation also increased the amounts of chlorophyll in fig leaves by 14%, the average of total fruit numbers by 134%, and the average of total fruit weight by 54% as compared to the average of other treatments treatments. Furthermore, the highest level of water productivity were in micro jet irrigation techniques, while it dropped by 40% with subsurface drip irrigation. The practical implications of this study involve boosting fig yield, refining water management strategies, increasing drought resistance, analyzing economic feasibility, gauging sustainability, and supporting the sharing of knowledge and skills for fig cultivation in semi-arid areas.