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A meta-analysis was conducted with the aim of exploring the influence of irrigation on potato yield, evapotranspiration (ET), and water-use efficiency (WUE) in northern China, considering factors such as irrigation methods, growing region, irrigation water-use efficiency (IWUE), irrigation frequency, soil types, and nitrogen (N) fertilizer rate. Overall, irrigation significantly increased potato yield and ET by an average of 45 and 54% compared to non-irrigation, respectively, but did not significantly increase the WUE. The increase in potato yield under irrigation is the most evident in aeolian sandy soil in northeast China and northwest China. Drip irrigation demonstrated the highest positive impact on both yield and WUE. Optimal yields were achieved with an irrigation amount ranging from 100 to 200 mm, while the highest WUE was observed with an irrigation amount of 30–50 mm. When the amount of irrigation exceeded 100 mm, the irrigation significantly resulted in decreased WUE compared to non-irrigation. The relative increase in yield per unit of irrigation amount and IWUE gradually decreased and eventually stabilized when the irrigation amount exceeded 100 mm. Therefore, the yield and WUE perform best when the irrigation amount is below 100 mm and the irrigation frequency is less than three times for sprinkling and flood irrigation methods. The greatest increases in yield and WUE under irrigation were found under a moderate N rate (150–250 kg N ha−1). Additionally, the relative increase in yield per unit of irrigation amount decreases gradually as the organic matter content increases. These findings suggest that the optimal benefits from irrigation might be realized when the irrigation amount is below 100 mm, with a moderate nitrogen fertilizer application and an irrigation frequency of three times. However, it is essential to consider local environmental factors such as the growing region, soil types, and organic carbon content. [ABSTRACT FROM AUTHOR]

Optimizing irrigation strategies is crucial for sustaining cotton production in the face of growing water scarcity. The three-year experimental study (2020–2022) focused on the impact of varying irrigation amounts (320, 370, and 420 mm) and frequencies (4-, 8-, and 12-day intervals) on cotton growth, yield, yield components, and fiber quality in southern Xinjiang. Employing a completely randomized design with three replications, the results indicated higher irrigation amounts resulted in numerically 2.5–7.5% higher lint yields compared to those under medium and low irrigation amounts, notably significant in 2021. Boll density emerged as the primary yield component influencing yield loss due to irrigation amount, followed by seed cotton weight boll−1. Increased boll density was associated with a greater total number of fruiting sites. Additionally, the increased seed cotton weight boll−1 could be linked to an increased seed number boll−1 and a decreased boll fraction at the lower fruiting branches with lower seed cotton weight boll−1. Higher irrigation frequency improved lint yield by increasing boll density, though a significant effect was observed only in 2020. Increased irrigation amounts generally led to longer fiber lengths but lower micronaire values, while increased irrigation frequency resulted in longer, stronger fibers and reduced micronaire values. Furthermore, the highest yield stability was observed under the condition of high irrigation amount and high frequency. This study holds certain guiding significance for water resource management in cotton production in arid regions. [ABSTRACT FROM AUTHOR]

Soil organic carbon is very important to increase crop yield. Understanding the composition changes and migration characteristics of SOC under different irrigation conditions in arid oasis areas is of great significance for the sustainable development of agro-ecosystem and the estimation of carbon balance of farmland ecosystem in arid areas. In this paper, classical statistics and geostatistics were used to study the leaching characteristics and migration laws of soil organic carbon under different irrigation conditions in Minqin Oasis, and the leaching amount and loss process and mechanism of SOC under different irrigation conditions were quantified. The research results showed that: (1) Irrigation increased the average 0–100 cm SOC content. After irrigation, SOC content decreased first and then increased with the increase in soil depth, with the maximum value of 8.56 g/kg and the minimum value of 1.82 g/kg. Compared with that before irrigation, SOC content in 0–30 cm surface layer was in leaching state, SOC content in 30–70 cm surface layer was accumulated, and SOC content in 70–100 cm surface layer had no obvious change. (2) Water was an important factor affecting soil carbon. The greater the irrigation amount, the higher the carbon leaching rate and the greater the migration amount. The SOC content in 0–30 cm soil layer was most significantly affected by irrigation, and the migration amount of SOC gradually decreased with the increase in soil depth. The maximum leaching rate of SOC was 36.8%, the minimum leaching rate was 13.5%, and its average leaching rate was 23.4%. (3) Due to the influence of soil infiltration rate under water, SOC content in different irrigation periods showed that the greatest SOC occurred in the 0–70 cm layer, and SOC content in soil was basically the same as that in non-irrigated areas on the fifth day after irrigation. (4) Precipitation, plastic film mulching, soil physical and chemical properties and other environmental factors were important factors affecting the migration and change in SOC content. [ABSTRACT FROM AUTHOR]

A two-year field experiment was conducted to evaluate the effect of irrigation and nitrogen amount on maize growth and water productivity for saline soil. The main treatments were four nitrogen levels 0 (N0), 215 (N1), 270 (N2), and 325 kg ha−1 (N3) and three irrigation levels 500 (W1), 400 (W2), and 300 mm (W3). The results demonstrated that all treatments were in salt leaching state in 2016 and in salt accumulation state in 2017. Soil salinity decreased with increasing nitrogen amount while nitrogen amount was lower than 270 kg ha−1 under W2, but increased with increasing nitrogen amount under W3. Compared with W1N2, the reduction in plant height and leaf area index of W2N2 was less than 7.0%. The total water consumption decreased with decreasing irrigation and nitrogen amount. Yield of W2N2 was only 5.0% less than W1N2 in 2016, but obtained the largest yield in 2017. Yield and water use efficiency were elevated while nitrogen amount increased from 0 to 270 kg ha−1, but were decreased while nitrogen amount exceeded 270 kg ha−1. Thus, irrigation amount 400 mm in combined with nitrogen amount 270 kg ha−1 could alleviate salt accumulation, promote maize growth, and ensure maize yield. [ABSTRACT FROM AUTHOR]

A meta-analysis was conducted with the aim of exploring the influence of irrigation on potato yield, evapotranspiration (ET), and water-use efficiency (WUE) in northern China, considering factors such as irrigation methods, growing region, irrigation water-use efficiency (IWUE), irrigation frequency, soil types, and nitrogen (N) fertilizer rate. Overall, irrigation significantly increased potato yield and ET by an average of 45 and 54% compared to non-irrigation, respectively, but did not significantly increase the WUE. The increase in potato yield under irrigation is the most evident in aeolian sandy soil in northeast China and northwest China. Drip irrigation demonstrated the highest positive impact on both yield and WUE. Optimal yields were achieved with an irrigation amount ranging from 100 to 200 mm, while the highest WUE was observed with an irrigation amount of 30–50 mm. When the amount of irrigation exceeded 100 mm, the irrigation significantly resulted in decreased WUE compared to non-irrigation. The relative increase in yield per unit of irrigation amount and IWUE gradually decreased and eventually stabilized when the irrigation amount exceeded 100 mm. Therefore, the yield and WUE perform best when the irrigation amount is below 100 mm and the irrigation frequency is less than three times for sprinkling and flood irrigation methods. The greatest increases in yield and WUE under irrigation were found under a moderate N rate (150–250 kg N ha−1). Additionally, the relative increase in yield per unit of irrigation amount decreases gradually as the organic matter content increases. These findings suggest that the optimal benefits from irrigation might be realized when the irrigation amount is below 100 mm, with a moderate nitrogen fertilizer application and an irrigation frequency of three times. However, it is essential to consider local environmental factors such as the growing region, soil types, and organic carbon content.

Water and nitrogen are vital factors limiting dry matter accumulation (DMA) and yield formation of spring maize. Simulation of DMA in spring maize under different irrigation and nitrogen application levels is conducive to better field management. Logistic model is a simple and effective measure to simulate the DMA. However, the coupling effect of water amount and nitrogen rate on logistic model parameters for spring maize in Northwest China has received little attention thus far. In this study, regression equations between logistic model parameters, water amount (i.e. irrigation plus rainfall), and nitrogen application rate were established and validated using independent data sets from three experiment sites (Wuwei in Gansu Province, Guyuan in Ningxia Province and Bayannur in Inner Mongolia Autonomous Region). Similarly, the empirical model of harvest index was established and validated. The results showed that these regression equations can accurately predict the dry matter accumulation and yield of spring maize. Therefore, this study can provide an alternative simple method to predict DMA and yield of spring maize under various water and nitrogen treatment in this area. [ABSTRACT FROM AUTHOR]

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The mechanism of greenhouse tomato growth and yield under the integrated water and fertilizer of moistube irrigation (MI) is not clear. Thus, to fill the research gap, a completely randomized trial design was used to study the effects of different irrigation amounts (I; to realize different I, the tube working pressure was 1 (I1), 2 (I2), 3 (I3) m) and fertilizer amounts (F, N-P-K: 20%-20%-20%; the F at a single time was 100 (F1), 200 (F2) and 300 (F3) kg/ha) on growth and yield of tomato. The results showed that with an increase in I, the photosynthetic rate (Pn) of leaves and total dry matter mass (TDM) first increased and then decreased, while the nutrition and the flavor indexes of fruit decreased. With an increase in F, the Pn of leaves, the TDM of tomato and the fruit quality increased at first and then decreased. The effects of I on the yield of tomato was higher than that of F. With an increase in I, the partial fertilizer productivity (PFP) increased at first and then decreased, and the water use efficiency (WUE) decreased by 13.96%. With an increase in F, the WUE increased at first and then decreased, and the PFP decreased by 148.97%. The conclusion based on a spatial analysis was consistent with the comprehensive evaluation of yield and water use efficiency, which showed that I2F2 was the best. [ABSTRACT FROM AUTHOR]

Freshwater resources are in a shortage in arid regions worldwide, especially in extremely arid desert areas. To solve this problem, highly saline groundwater is used for drip irrigation of desert plants. Since more irrigation infiltrating into the deep soil cannot be absorbed and utilized by desert plants, it is crucial to determine optimal water-saving irrigation regimes. In this study, we examined the effects of irrigation regimes on the soil water dynamics of two typical woody halophyte species (Haloxylon and Calligonum), and quantified the irrigation intervals and periods based on a field test of precision irrigation control in the Taklimakan Desert Highway shelterbelt. Results showed that the change in soil moisture of two species in the shallow 0–60 cm layer could be divided into a rapid decline period (1–9 d), a slow decline period (9–19 d), and a relatively stable period (19–39 d) after irrigation. The decrease rate of soil moisture at the 0–60 cm depth was significantly higher than that at the 60–200 cm depth. The irrigation regime combining 35 mm irrigation with 10 days was beneficial to soil water storage and plant use with respect to Calligonum, while the irrigation regime combining 35 mm irrigation with 40 days was best for Haloxylon. Increasing the single irrigation amount and prolonging the irrigation period can further enable the more effective use of irrigation water. This study highlights that saline groundwater irrigation provides potential advantages for desert plants' survival under reasonable irrigation regimes. [ABSTRACT FROM AUTHOR]

Aims: This study was conducted under Hatay, Turkey ecological conditions in the second crop season and aimed to determine the effect of irrigation numbers and amounts on some quality characteristics of popcorn (Zea mays everta Sturt.) Methods and Results: Antcin 98 popcorn cultivar was cultivated in Hatay Mustafa Kemal University Research Area in the second crop season of 2015 under five irrigation managements as follows: (I1) 12 times (1757 mm), (I2) 8 times (1449 mm), (I3) 6 times (1148 mm), (I4) 5 times (989 mm) and (I5) 4 times (800 mm). After harvest, quality analysis were carried out with 4 repetitions for each irrigation treatment and kernel size, crude protein, crude oil and crude ash ratios were determined. It’s revealed that all the parameters investigated significantly affected by irrigation managements. According to the results; the lowest grain size (89.00 grains 10 g-1) and the highest crude protein ratio (10.59%) were obtained from the I5 treatment, while the highest crude ash (2.04%) and crude oil (5.74%) ratios were obtained from the I4 treatment. It was determined that as the number of irrigation decreased, the crude protein ratio increased, the crude ash and crude oil ratios increased to a certain level and then decreased. With the correlation analysis performed, significant and positive relationships were determined between kernel size and crude protein (r = 0.686) and between crude oil and crude ash (r = 0.852). Conclusions: The results showed that excessive irrigations cannot increase kernel size, which directly affects the popping volume, which is one of the most important quality criteria of popcorn, However, the nutritional values can be changed by applying different irrigation managements. It can be concluded that under similar growing and climatic conditions, popcorn can be produced with 5 irrigations and a total of 989 mm of irrigation water. Significance and Impact of the Study: The study revealed the effects of different irrigation numbers and amounts on some quality characteristics of popcorn grown under second crop season conditions. [ABSTRACT FROM AUTHOR]

High temperatures in summer can prevent people from using urban green spaces. Irrigating urban green spaces is a promising strategy to reduce temperatures. In this study, we aimed to a) identify the proportional contribution of different irrigation cooling mechanisms and b) quantify the impacts of different irrigation amounts (from 2 to 30 mm d−1) on the cooling effect of irrigating turfgrass in Melbourne, Australia. We first used a field experiment in Melbourne to provide empirical data to calibrate and verify the performance of an urban ecohydrological model, UT&C. Then, we used UT&C to predict the impacts of irrigating turfgrass on evapotranspiration, the energy balance and microclimate. UT&C predicted that irrigating turfgrass 4 mm d−1 would increase the evaporation from grass canopy and soil surface by 0.2 and 0.6 mm d−1, respectively, whereas it would reduce transpiration by 0.6 mm d−1 due to intercepted water covering part of the grass canopy following the irrigation. UT&C predicted that daytime (10:00–16:59) mean air temperature reductions would increase from 0.2 to 0.4 °C when the irrigation amount increased from 2 to 4 mm d−1. However, increasing the irrigation amount beyond 4 mm d−1 would not increase the cooling benefits. [Display omitted] • We measured the cooling effects of irrigating urban green spaces. • We used a model to identify cooling mechanisms and optimal ideal irrigation amount. • Irrigating grass increased evaporation from soil surface and canopy interception. • Increasing irrigation amount beyond 4 mm d−1 would not strengthen cooling effect. • Irrigating grass 4 mm d−1 significantly reduced daytime air temperature by 0.4 °C. [ABSTRACT FROM AUTHOR]

Desertification control is an important issue that must be considered in modern society. In order to effectively improve the accuracy and practicability of the evaluation algorithm of desertification control effect, the Alhagi sparsifolia index under different irrigation amount was taken as the research object, and the evaluation algorithm of desertification control effect was proposed. In the "vegetation-sandstorm-soil" index system, a number of indexes were selected according to the core environmental parameters of Alhagi sparsifolia and grassland desertification. And the analytic hierarchy process, remote sensing, geographic information system, and landscape technology were used to assign index weights of desertification control capacity, which were calculated by multiple discriminant matrices. Finally, the data regression analysis was performed based on remote sensing and computer image information screening and processing to determine the final evaluation results. The experimental data show that the true positive rate of the algorithm in this paper is between 160 and 200, which is within a large range of advantages, indicating that the overall evaluation accuracy of the algorithm is high and the evaluation effect is perfect. [ABSTRACT FROM AUTHOR]

In order to explore the effects of different irrigation amounts on the length and width of new citrus leaves under the pre¬cise root domain irrigation technology, citrus was taken as the research object and set different irrigation amount for irrigation. In the experimental group under the precise root field irrigation, 35, 30, 25L/ (plant • times) were respectively set and irrigated once in sev¬en days； in the control group under the micro - sprinkling irrigation method, 130L/(plant • times) irrigated once in 15 days. After ir¬rigating different amount of water, the growth of slightly new tip of the tree and the length and width of new leaves were recorded. Re¬sults showed that the root domain precision irrigation under different irrigation amount had a significantly influence on the new tip of the tree and the length and width of new leaves. In the 14 days observation period, test II had the best growth potential, the total growth of the new tip of the tree was 72. 1 mm, compared with the control group, the growth volume increased by 17. 7 mm and increased by 32.5% year - on - year. The total growth of new leaf length was 48. 9 mm, increased by 9. 6 mm compared with the control group, in¬creased by 24.4% year - on - year, and the total growth of leaf width was 23. 3 mm, which was higher than that of the control. The growth of the group increased by 5. 3 mm, a year - on - year increase of 29. 4% . Therefore, the irrigation amount of 30 L/( plant • times) under the precise root domain irrigation technology is more suitable for the growth of fresh citrus leaves. [ABSTRACT FROM AUTHOR]

In water-scarce regions, alternate-furrow irrigation (AFI)—alternately wetting half of the plant roots—has proven to be an effective water-saving approach without compromising yield. However, the extent to which AFI with wastewater affects N cycling genes remains poorly studied. We aimed to investigate changes in main N transformation processes, bacterial and fungal community composition, as well as relative abundance of N cycle-associated genes in soil receiving AFI with swine wastewater. The experimental plan included three irrigation rates, irrigating pepper plants with 50%, 65%, and 80% of the amount of water required under conventional furrow irrigation to prevent the crop suffering water stress. Each treatment had a groundwater irrigation control. We measured edaphic factors, microbial community composition, and relative abundance of genes in rhizosphere and bulk soils. Altering water use in AFI did not exert a significant effect on bacterial and fungal communities. By increasing the irrigation rate of wastewater, relative abundances of nifH, bacterial and archaeal amoA and nosZ genes decreased, whereas those of nirK and nirS genes increased in the rhizosphere soil; nitrification rate did not decrease and the denitrification rate remained unchanged in both rhizosphere and bulk soil, implying that appropriate increase of wastewater use by AFI can improve N use efficiency. [ABSTRACT FROM AUTHOR]

Uncertainty in future availability of irrigation water and regulation of nutrient amount, management strategies for irrigation and nitrogen (N) are essential to maximize the crop productivity. To study the response of irrigation and N on water productivity and economic return of maize (Zea mays L.) grain yield, an experiment was conducted at Water Management Research Center, University of Agriculture Faisalabad, Pakistan in 2015 and 2016. Treatments included of full and three reduced levels of irrigation, with four rates of N fertilization. An empirical model was developed using observed grain yield for irrigation and N levels. Results from model and economic analysis showed that the N rates of 235, 229, 233, and 210 kg ha−1 were the most economical optimum N rates to achieve the economic yield of 9321, 8937, 5748, and 3493 kg ha−1 at 100%, 80%, 60%, and 40% irrigation levels, respectively. Economic optimum N rates were further explored to find out the optimum level of irrigation as a function of the total water applied using a quadratic equation. The results showed that 520 mm is the optimum level of irrigation for the entire growing season in 2015 and 2016. Results also revealed that yield is not significantly affected by reducing the irrigation from full irrigation to 80% of full irrigation. It is concluded from the study that the relationship between irrigation and N can be used for efficient management of irrigation and N and to reduce the losses of N to avoid the economic loss and environmental hazards. The empirical equation can help farmers to optimize irrigation and N to obtain maximum economic return in semi-arid regions with sandy loam soils. [ABSTRACT FROM AUTHOR]

This study aims at discussing the effects of planting row spacing and irrigation amount on the plant growth, chlorophyll fluorescence parameters and yield of tomato, the purpose is to obtain the suitable arrangement of irrigation amount and planting row spacing for greenhouse tomato in Northwest China. The experiment was conducted in a solar greenhouse at the Green Lily fruit and vegetable cooperatives in Yangling Agricultural Hi-tech Industries Demonstration Zone in Shaanxi province from January to June in 2016. The cultivated variety of tomato in the experiment was HL2109. The treatments comprised three planting row spacing (L1(60 cm), L2(45 cm), L3 (30 cm))with 80 cm ridge distance and 35 cm plant spacing. Based on the cumulative evaporation from a 20 cm diameter pan between two irrigations (E), 0.6 E, 0.8 E, 1.0 E, 1.2 E were set as four different levels of irrigation amount, when the cumulative evaporation reached (20±3) mm, irrigation will be conduct. Twelve treatments were experimented totally and every treatment was replicated three times in randomized complete block designs. Based on the growth indexes, chlorophyll fluorescence parameters in different growth stages and the leaf area index, net photosynthetic rate of tomato plants during the critical period of yield formation, the effects of different row spacing and irrigation amount on tomato growth, photosynthetic physiological activities and yield were analyzed, and the relationship between different growth and physiological indexes with yield were studied. The results showed that tomato growth index: chlorophyll fluorescence parameters, net photosynthetic rate, yield and irrigation water use efficiency were all affected by both planting row spacing and irrigation amount in varying degrees, but there is no significant interaction between the two factors. Low planting row spacing treatment(L3) resulted in redundant plant growth and excessive LAI, thereby photosynthetic physiological activities of crop population were inhibited, finally causing lower yield and irrigation water use efficiency. Excessively low irrigation amount inhibited photosynthetic physiological activities and showed a cumulative effect of water stress with the growth period of tomato plants. By path analysis, LAI and Pn have the most direct impact on yield among the indicators, improving the Pn is an important way to increase crop yield. Plant height and stem diameter have a good regression relationship with leaf area index(P=0.004 6), plant with large stem diameter and low height has suitable leaf area index, which is beneficial to yield formation. The yield of tomato followed a downward quadratic parabola shape with the increase of irrigation amount and planting row spacing, however, when planting row spacing and irrigation amount reached 45 cm and 0.8E respectively, continuing to increase planting row spacing and irrigation amount would not significantly increase yield. Considering the irrigation water use efficiency and yield, L1-0.8E and L2-0.8E treatment were better than others. Compared with the highest yield treatment (L1-1.2E), L1-0.8E and L2-0.8E treatments can increase irrigation water use efficiency by 36.00% and 29.29% when yield reduced by only 4.28% and 9.00%. So, when the ridge distance is 80 cm and the plant spacing is 35 cm, the planting row distance selected 45-60 cm, the irrigation quantity is set to 0.8E would be the appropriate combination of irrigation amount and planting row spacing of greenhouse tomato in Northwest China. [ABSTRACT FROM AUTHOR]

Based on loam soil in different design density 1.4 g/cm3, 1.5 g/cm3, 1.6 g/cm3, we had done the test of the changes relationship between the soil containing water and the soil water potential, and analyzed the soil water potential trends of the loam soil in the design of different bulk density. The results show that the value of loam soil water potential is in the range of 57 to 140 kpa under the same soil containing water (gravimetric water content 12.5%) and the design of three soil bulk density, and present that the greater the soil bulk density, the smaller the soil water potential. The changing range of them is in trend of decreasing. All of these experimental studies will be benefit to choose the suitable discharge of the dripper for drip irrigation system, and make full use of the natural energy of the soil water potential, using it as the control index of irrigation system. At the same time, these results can provides a theoretical basis further for researching on the crop root zone soil moisture migration regularity and determining the optimal soil moisture environment. [ABSTRACT FROM AUTHOR]

Plastic film mulching under drip irrigation is a key cotton cultivation technology that can save water and increase yield in arid regions. However, the long-term promotion of film mulching has resulted in increasingly serious problems related to residual film pollution. We hypothesized that deep drip irrigation and optimized irrigation can ensure the sustainability of yield of non-film cotton; thus, film is not necessary under this planting system. To address the above issues, we investigated the effects of different irrigation volumes (in m3 ha−1: W 1 , 2649; W 2 , 2925; W 3 , 3201; W 4 , 3477; W 5 , 3753) on the soil water and salt distribution, agronomic attributes, biomass accumulation, yield composition and water use efficiency (WUE) of non-film cotton grown under deep drip irrigation in a two-year field trial. We also explored possible ways to exploit the full potential of decreasing water consumption and enhancing cotton production. The results showed that the seed cotton yield of W 3 was 7.5%, 7.1% and 3.2% higher than those of W 1 , W 2 and W 5 , respectively, while it was 5.2% lower than that of W 4 across the two-year study. Moreover, there was no significant difference in seed yield or WUE between the W 3 and W 4 treatments. Compared with the W 2 treatment, the W 3 treatment delayed the total growth period by only 0–2 d, the conductivity in the 0–10 cm soil layer was increased by 9.3–22.9%, and the soil water content in the 0–20 cm soil layer was increased by 1.7–4.0%. The cotton plant biomass and reproductive organ biomass increased with the amount of irrigation and followed this order W 5 > W 4 , W 3 , W 2 > W 1. Seed cotton yield was significantly correlated with effective bolls, while WUE was negatively correlated with vegetative organ biomass at the flowering and boll setting stages. Overall, the results suggested that under the non-film conditions, an irrigation amount of 3201 m3 ha−1 would improve the eco-friendliness and efficiency of cotton production systems in arid regions. • Non film deep-drip irrigation (NDI) system can solve the residual membrane pollution. • Salt accumulates on the surface of the soil under NDI system. • Optimizing irrigation under NDI system can achieve high-efficiency cotton production. • Maintaining proper vegetative organs in the later growth stage is conducive to yield increment. [ABSTRACT FROM AUTHOR]

In recent years, the nutritional quality of vegetables has been increasingly concerned by people and investigated by researchers. However, the decline in vegetable internal quality is common due to excessive irrigation and irrational fertilization. Although tomatoes have been grown successfully for many years, there is no accurate formula or recipe on amount of irrigation or fertilizer levels to get tomato fruit with high quality. For tomato fruits, the nutritional quality largely depends on the content of soluble solids, soluble sugar, titratible acid, Vitamine C and lycopene, some of which are correlated with each other. Therefore, tomato nutritional quality could not be assessed according to any one of these attributes. But the comprehensive evaluation of vegetable nutritional quality has not been well studied yet. To construct a comprehensive nutritional quality index of tomato fruits and investigate its response to irrigation amount and fertilizer rates of nitrogen, phosphorus and potassium, a composite quadratic orthogonal regressive rotation design of four factors and five levels was used in a pot experiment. The contents of soluble solids, soluble sugar, titratable acid, lycopene, Vitamin C and sugar-acid ratio were determined for tomato fruits. By using entropy weighting method, the objective weights of six single quality attributes were calculated based on measurements of these attributes. The subjective weights of these six attributes were calculated based on the analytic hierarchy process (AHP) from survey data from both consumers and horticulture experts. Based on these, the comprehensive weighting method of game theory was used to determine the balanced weight of single tomato quality attributes. Results indicated that the attributes were ranked based on their importance by lycopene>sugar-acid ratio>Vitamin C>soluble sugar>soluble solid>titratable acid. The comprehensive nutritional quality index was constructed according to the technique for order preference by similarity to ideal solution (TOPSIS). Moreover, a regression model on the amount of irrigation water and fertilizers and tomato comprehensive nutritional quality index was established. Based on the regression equation, the single, interactive and coupling effects of these four experimental factors on the comprehensive nutritional quality index were analyzed. The results showed that the main effects of four experimental factors on the comprehensive nutritional quality were ordered by P rate>N rate>irrigation amount>K rate. If codes of other three factors were zero, the comprehensive nutritional quality showed a downward quadratic parabola in response to the increase of irrigation amount, as it did in the case of N rate. It is interesting that an upward quadratic parabola occurred with the increase of K rate. The comprehensive nutritional quality increased linearly with P rate. Interaction between amount of irrigation and N, P and K fertilizers significantly affected comprehensive quality of tomato fruits. It indicated that comprehensive tomato nutritional quality decreased with excess input of irrigation amount and N fertilizer, and could be improved by appropriate supply of P and K fertilizers. The findings from this study also allowed us to optimize comprehensive evaluation of vegetable quality that could be used to study the management of water and fertilizers in the future. [ABSTRACT FROM AUTHOR]

Hetao Irrigation District (HID), one of the main grain-producing areas in China, is facing the severe challenge of agricultural water shortages. Improving water use efficiency (WUE) is the most appropriate way to achieve sustainable agricultural development and obtain high returns. However, farmers knew little about efficient irrigation strategies for flood-irrigated fields in the HID. In this study, the Noah-MP Land Surface Model (LSM) with dynamic crop and irrigation schemes is used to jointly simulate the maize yield and irrigation amount in the HID from 2003 to 2012. A sensitivity test for ten sets of irrigation setup with different soil moisture (SM) triggering thresholds (CRI=0–1) is conducted, and the corresponding WUE and irrigation water use efficiency (IWUE) are evaluated and analyzed. In addition, irrigation at different crop growth stages affects total irrigation amounts and crop yield. The results show that under rain-fed conditions, the severe SM deficit during the growing season significantly decreases the maize yield in the HID, with almost no harvest in dry years. With traditional flood irrigation, the irrigation amount per unit area exceeds 1000 mm, leading to low WUE and IWUE, while more than 18–25% of irrigation water is wasted as runoff. With the increase of irrigation intensity, both WUE and IWUE show a significant diminishing marginal effect, usually occurring when SM is greater than 0.24–0.27 m3/m3. The optimal WUE is obtained near CRI= 0.6, while the worst WUE is obtained at CRI= 1. In a normal year, efficient irrigation amount is about 390–480 mm, 53–63% less than that in flood irrigation. In this scenario, most irrigation water becomes SM and transpiration, and less than 5% becomes runoff. With effective irrigation in the reproductive stage, only a small amount of irrigation is needed to promote yield formation. Fully considering the maize yield, WUE, ecosystems, and the available water resources in the HID, the recommended irrigation amount is about 600–650 mm to achieve the optimal maize yield and WUE. • The Noah-MP model reasonably simulates soil moisture and irrigation amount in two sites in the Hetao Irrigation District. • Efficient irrigation could save up to 95% of water loss to runoff compared to flood irrigation. • At optimal water use efficiency, soil moisture ranges from 0.24 m3/m3 to 0.27 m3/m3. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effect of irrigation amount and irrigation frequency on drip-irrigated flue-cured tobacco evapotranspiration (ETa), yield, and water use efficiency. Four irrigation treatment levels were imposed: 100% IRT (fully irrigated treatment, no stress), 85% IRT, 70% IRT, RFT (rainfed treatment), and high, medium, and low irrigation frequencies were set. The relationship between irrigation volume and yield is a quadratic curve. The evapotranspiration had a positive relationship with the irrigation amount. The yield of flue-cured tobacco was the highest in 2016 (wet year), and the corresponding ETa was the smallest. The irrigation water use efficiency (IWUE) in the driest year, 2017, was lower than IWUE in the wet years 2015 and 2016, and the crop water use efficiency (CWUE) had similar results for the three years. IWUE increased with irrigation amount. The effect of irrigation frequency on CWUE was not significant. The CWUE had a positive relationship with yield. No significant differences due to irrigation frequency were found for yield. [ABSTRACT FROM AUTHOR]