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The effects of water deficit on maize growth and physiological activities have been extensively studied. However, there are few studies about how various nitrogen (N) fertilizer types alleviate the impact of water stress on maize yield. A two-year field experiment was conducted to explore the effects of N type on maize growth, physiological characteristics and gain yield under various water-stressed conditions in 2019 and 2020. This experiment included three irrigation levels of W1 (60% ET c , ET c is crop evapotranspiration), W2 (80% ET c) and W3 (100% ET c), and three N fertilizer types of urea (U), slow-release nitrogen fertilizer (SRF) and blending U and SRF (UNS). The results showed that W1 and W2 significantly reduced maize leaf area index and leaf N content, which declined maize net photosynthetic rate (P n), transpiration rate (T r) and chlorophyll fluorescence, inhibited chlorophyll synthesis and thus reduced maize yield. W3 not only increased maize growth, P n and T r , but also enhanced the correlation between P n , chlorophyll content, chlorophyll fluorescence parameters and leaf area index/leaf N content. The application of UNS alleviated the grain yield reduction associated with water stress. Under W1 (W2), the grain yield in UNS were 3.6–22.1% (10.4–25.0%) and 4.4–24.2% (5.3–15.4%) greater than that in U and SRF, respectively. Although W3SRF obtained the highest yield grain among all the treatments, no significant difference was found between W3UNS and W3SRF. Under the same irrigation amount, UNS increased the water productivity compared with U. In conclusion, UNS could stabilize grain yield by regulating maize leaf functional traits to cope with future climate change and ensure regional food security. • LAI and leaf N content can evaluate the response of leaf development process to water deficit. • W3 increased the correlation coefficients between leaf function index and LAI/leaf N content. • UNS alleviated the negative effects of water deficit on leaf functional index of maize. • UNS could stabilize grain yield by regulating maize leaf functional traits. [ABSTRACT FROM AUTHOR]

Optimising the management of water and fertilizer, and fully exploiting the positive effects of the coupling of water and fertilizer, are important ways of achieving high crop yields and promoting the sustainable development of water-efficient agriculture. The objective of this study was to investigate the coupling effects of different irrigation levels and different mixing ratios of slow-release nitrogen fertilizers on the physiological growth characteristics and yield of winter wheat in Guanzhong region under drip irrigation. In this study, field experiments were conducted in two winter wheat growing seasons, 2018–2019 and 2019–2020. The study included three irrigation levels: W1 (60% ETc, where ETc is the evapotranspiration of the crop), W2 (80% ETc), and W3 (100% ETc); and four N fertilizer treatments: U (100% urea), UNS1 (urea: slow-release N fertilizer = 1:1), UNS2 (urea: slow-release N fertilizer = 1:3) and SRF (100% slow-release N fertilizer). Compared to W1 and W2, W3 prolonged the winter wheat leaf functional period, increased leaf area index and net photosynthetic rate (P n), and promoted dry matter accumulation. The total N content of winter wheat decreased by 22.67% and 9.93% under W1 and W2 conditions, respectively. The nitrogen use efficiency (NUE) decreased by 5.87% and 1.97%, respectively, leading to a decrease in yield. Slow-release nitrogen fertilizer (SRF) and its mixture treatments (UNS1, UNS2) increased post-flowering nitrogen uptake in winter wheat compared to U. At the same irrigation level, water use efficiency (WUE) was increased by 34.03%, 13.35%, and 20.86% in the UNS2 treatment compared to U, UNS1, and SRF, respectively. W3UNS2 obtained the highest grain yield: 8026.32 kg hm−2 (2018–2019) and 8993.25 (2019–2020) kg hm−2, with a 9.85–68.24% yield increase compared to other treatments. Und4er the treatments of this study, yield, WUE, and NUE of winter wheat reached 90% of the maximum at irrigation levels of 82.04–91.83% ETc and 59.18–83.67% of slow-release N fertilizer in blended fertilizer. Under water stress conditions, UNS1 and UNS2 can mitigate the effects of water deficit on plant growth and stabilize grain yield. This study provides useful information for optimising water and nitrogen management decisions for winter wheat in semi-arid climatic regions, and contributes to the promotion of sustainable development of wheat production and water-efficient agriculture. • The two-year drip trial was conducted in a sheltered canopy in GuanZhong. • Field trial address in the coupling impacts of irrigation&fertilizer on winter wheat. • Recommended irrigation volumes and mixing ratios were obtained using modelling. • Blended slow-release nitrogen fertilizer can effectively mitigate the drought effects. • 100% ETc with U:SRF = 1:3 is the most recommended irrigation and fertilization option. [ABSTRACT FROM AUTHOR]

Highlights • Effects of irrigation and fertilizer supply on grain filling characteristics were explored. • Temporal dynamics of grain weight was simulated using determinate-growth equation. • Fertilizer had significantly influence the appearance time of maximum filling rate and growth termination time. • Grain weight percentage of spike weight and spike moisture content had extremely significant relationship with grain weight. • Mild water deficit and appropriate fertilization improved grain filling and productivity. Abstract In the semi-arid regions of the world, irrigation and fertilization are essential for cereals growth and production because of water shortages and unfertile soils. However, inappropriate water and fertilizer management always causes unstable grain weight and yield. This study aims to explore the responses of grain filling characteristics, grain weight and productivity of winter wheat to varying water and fertilizer supplies. A three-year (2014–2017) experiment was conducted on winter wheat (Triticum aestivum L. 'Xinong 979') under drip fertigation, with three irrigation rates and three fertilization rates. The temporal dynamics of grain weight was simulated using determinate-growth equation. The appearance time of maximum filling rate (t m) and growth termination time (t e) increased as fertilization rate increased, whereas the maximum and average filling rate increased and then had a slight decrease. The t m and t e decreased with the increase of water deficit, the mild water deficit obtained higher grain filling rate. The grain weight percentage of spike weight (GPS) and spike moisture content (SMC) had extremely significant correlations with grain weight. GPS tended to decrease one week before maturity, and declined with the increase in water stress. SMC decreased in a parabolic form, and exhibited a dramatic decline about one week before maturity. With the increase of water or fertilizer supply, the grain weight firstly increased and then decreased, where the mild water deficit and appropriate fertilization improve grain filling and productivity of winter wheat. [ABSTRACT FROM AUTHOR]

Precise nutrient diagnosis is the basis of accurate simulation of maize (Zea mays L.) grain yield and high-efficient utilization of resources under the changing climate. However, the combined effects of supplementary irrigation and fertilizer application on plant stoichiometry of various maize cultivars in water-limited and nutrient-deficient regions are still poorly understood. A three consecutive year field experiment (2015−2017) was conducted on two maize cultivars (QL14 and ZD958) in northwest China, with two irrigation treatments (RF: rain-fed and DI: drip irrigation) and two fertilization treatments (F0: no fertilization and F1: local fertilization practice). The results showed that the radiation use efficiency for biomass yield of QL14 with fertilization under drip irrigation was increased by 7.39% than that of ZD958. DI (70.19 kg kg−1) and ZD958 (68.55 kg kg−1) obtained significantly higher physiological efficiency of nitrogen fertilizer than RF (59.52 kg kg−1) and QL14 (61.17 kg kg−1), respectively. Both plant and grain N:P ratios under F1 were higher than those under F0. QL14 had significantly higher grain N:P ratio (4.64) than ZD958 (4.26) under DIF1. Grain yield was increased obviously when grain N:P ratio and plant N:K stoichiometry were greater than 4.0 and 1.2, respectively. The newly released maize cultivar (QL14) was highly recommended as forage and cereal crops, since QL14 obtained significantly higher leaf and stem dry matter even under severe drought and low soil fertility conditions. Our study provides an opportunity to achieve high-yielding maize systems in northwest China and maybe other regions with similar environments, and the data will help inform policies and strategic plans for the effective use of water and fertilizer resources. • Nutrient stoichiometry and radiation use efficiency of two maize cultivars were explored. • There was a linear relationship between grain N and P uptake. • Grain yield was increased obviously when grain N:P ratio was greater than 4.0. • QL14 with higher leaf and stem dry matter was recommended as forage and cereal crops. [ABSTRACT FROM AUTHOR]

The excessive irrigation and fertilization are common in wheat (Triticum aestivum L.) production in northwest China, which not only results in resources waste and environmental pollution, but also not necessarily guarantee high wheat yield due to the plant overgrowth. It is thus crucial to explore a suitable irrigation and fertilization strategy that benefits high-yield wheat cultivation by regulating post-anthesis dry matter accumulation and translocation. A consecutive four-season field experiment (2014–2018) was undertaken on drip-fertigated winter wheat with three irrigation levels based on the soil moisture content of moistening layers (W1: normal irrigation, W2: mild deficit irrigation, W3: severe deficit irrigation) and three fertilization (N-P 2 O 5 -K 2 O) rates (F1: 175–117–150 kg ha−1, F2: 125–84–108 kg ha−1, F3: 75–50–65 kg ha−1). The results showed that the logistic growth equation could well describe the accumulation process of aboveground dry matter with R 2 ranging 0.989 − 0.999 (P < 0.01). Water stress advanced the thermal time required from sowing to the maximum aboveground dry matter rate, while the maximum aboveground dry matter rate and average accumulated rate of aboveground dry matter increased with the increase of irrigation and fertilization regimes. Dry matter translocation showed a negative relationship with fertilization rate. However, both the post-anthesis dry matter accumulation and its contribution to total dry matter at maturity (CDMA) increased with the increasing fertilization rate. With the increase of water and fertilizer supply, dry matter translocation efficiency decreased, but CDMA showed the opposite trend. The post-anthesis dry matter accumulation was positively related to winter wheat grain yield. When the grain yield reached above 7.5 Mg ha−1 in northwest China, the post-anthesis accumulated dry matter should be more than 4.7 Mg ha−1. It was concluded that the mild deficit irrigation along with N-P 2 O 5 -K 2 O fertilization of 125–84–108 kg ha−1 enhanced the productivity of winter wheat by increasing the post-anthesis dry matter translocation and accumulation. ● Water stress advanced the thermal time required from sowing to maximum aboveground dry matter rate. ● Dry matter translocation showed a negative relationship with fertilization rate. ● Post-anthesis dry matter accumulation was positively associated with grain yield. ● Mild water deficit and 125–84–108 kg N-P 2 O 5 -K 2 O ha−1 increased post-anthesis dry matter translocation and grain yield. [ABSTRACT FROM AUTHOR]

The over-application of irrigation and chemical fertilization in the greenhouse vegetable production system (GVPS) in China can jeopardize fruit quality, compromise economic profit and waste resources. Seeking optimal water and fertilizer supply mode for GVPS is urgently required to improve resource use efficiency and economic benefit. A greenhouse experiment was conducted during four consecutive tomato growing seasons to investigate the combined effects of various irrigation levels and fertilization practices on yield, fruit quality, economic benefit, water use efficiency (WUE) and nitrogen use efficiency (NUE) of drip-fertigated tomato, and to obtain the optimal water and fertilizer supply practice by the principal component analysis (PCA). On the basis of full irrigation (W1: 100%ET c , ET c was the crop evapotranspiration), two deficit irrigation levels (W2: 75%ET c , W3: 50%ET c) were set. Except for the conventional fertilization practice used by local farmers (CC: chicken manures for basal application and chemical fertilizer for topdressing), four other fertilization practices were considered, including soluble organic fertilizers for topdressing (SO), soluble chemical fertilizers for topdressing (SC), both soluble organic and chemical fertilizers for topdressing (SOSC), and a control with no fertilizer application under full irrigation (CK). The results showed that SOSC obtained relatively high plant nitrogen uptake, net profit and WUE, and significantly improved tomato yield. Organic fertilizers addition reduced nitrate content in tomato fruits. Deficit irrigation promoted CC to obtain higher WUE than SC. According to the result of PCA, the comprehensive ranking of SOSC was first among the fertilization practices, regardless of irrigation levels and growing seasons. W1SOSC and W2SOSC were highly recommended for greenhouse tomato production in spring and autumn seasons, respectively. ● Drip irrigation and fertilization effects on yield and economic benefit of tomato were explored. ● Organic fertilizers addition reduced nitrate content in tomato fruits. ● The comprehensive ranking of soluble organic and chemical fertilizers for topdressing was first. ● Soluble organic and chemical fertilizers combined with full irrigation or 75% full irrigation was recommended. [ABSTRACT FROM AUTHOR]

Increasing the capacity of plants to assimilate carbon (source), or to tap into the internal carbon reservoir (sink), has the potential of realizing high and stable yield under a more variable climate. A three-year field experiment was conducted to explore the source-sink relationships of two maize (Zea mays L.) cultivars in response to various water and fertilizer inputs, and evaluate the yield sustainability in northwest China. There were two fertilization rates (unfertilized, F0; fertilized, F1), two irrigation strategies (rainfed, RF; supplemental drip irrigation, DI) and two maize cultivars (ZD958 and QL14). The results showed that the newly released maize cultivar (QL14) had higher leaf chlorophyll content at the silking and grain-filling stages than the old one (ZD958); meanwhile, QL14 had higher root dry matter at maturity than ZD958 under DIF1. The aboveground and root dry matter increased with the amount of water and fertilizer, while the root-shoot ratio decreased. Cultivar significantly affected the vegetative organ dry matter partitioning, especially under severe drought at the silking stage. QL14 had stronger root system and larger leaf dry matter than ZD958, and was more drought-resistant under serious water-stressed conditions. Dry matter translocation (DMT) was crucial for grain yield formation under limited nutrients conditions, and ~55% of total dry matter at maturity was accumulated at the grain-filling stage under adequate water and fertilizer conditions. DIF1 had higher sustainable yield index (SYI) than RFF1. There was no significant difference in grain yield between the two maize cultivars under DIF1, but the average SYI of QL14 (0.94) was greater than that of ZD958 (0.89). The present study indicates that the newly released maize cultivar (QL14) with stronger root system and stay-green characteristics is beneficial for increasing drought resistance and keeping yield stable in the semi-humid and drought-prone region of northwest China. ● Source-sink relationship and yield stability of two maize cultivars were explored. ● Dry matter increased with water and fertilizer supply, while root-shoot ratio decreased. ● Dry matter translocation of maize was crucial for yield formation. ● Stronger root and stay-green of maize cultivar kept yield stability. [ABSTRACT FROM AUTHOR]

• Full irrigation (100 %ET c) improved plant growth and yield of greenhouse tomato. • 75 %ET c obtained higher WUE and lower unmarketable yield. • 100 %ET c tended to shorten rapid growth period of aboveground biomass and improve maximum growth rate. • The lowest total water consumption occurred at the blooming and setting stage. Agriculture is the largest consumer of scarce water resources and irrigation serves as the sole source of water for greenhouse tomato production. It is an urgent task to seek an appropriate deficit irrigation strategy that is beneficial for high marketable yield, fruit quality, saving irrigation water and ultimately improving water use efficiency. A four-season experiment was conducted on drip-irrigated greenhouse tomato during Autumn 2015-Spring 2017 with three irrigation regimes, i.e., 100 %ET c (crop evapotranspiration) (W1), 75 %ET c (W2) and 50 %ET c (W3). The results showed that aboveground biomass, leaf area index (LAI), plant height and fruit yield increased with increasing irrigation amount. However, soluble solids, vitamin C and soluble sugar of tomato fruits were lowest under W1. W2 markedly reduced unmarketable fruits and more small-sized fruits were harvested at the late stage under W1. Through fitting the relationship between cumulative temperature and aboveground biomass using logistic equations, it was found that average duration of the rapid growth period (t d) and the time when growth rate reached the maximum value (t m) increased as irrigation amount decreased. Conversely, the maximum growth rate during the rapid growth period (v m) decreased with the increase of water deficit. The highest total water consumption (278.05 mm), lowest total yield water use efficiency (25.12 kg m−3) and marketable yield water use efficiency (22.87 kg m−3) were obtained under W1. The smallest total water consumption (27.01–50.75 mm) occurred at the blooming and setting stage. Based on the results of path analysis, aboveground biomass and average fruit weight were important indexes affecting yield positively. It is concluded that deficit drip irrigation with 75 %ET c has the potential of supporting tomato growth, improving marketable yield and WUE as a result of less unmarketable yield and bigger fruit size. [ABSTRACT FROM AUTHOR]

No-tillage with limited supplementary irrigation is promising for improving crop growth and ensuring sustainable crop yield in semi-arid and semi-humid areas defined by their water scarcity and uneven seasonal precipitation distribution. Choosing effective irrigation methods and scheduling to improve irrigation water use efficiency (IWUE) and reduce the risk of soil nitrate leaching has become increasingly necessary for crop management. Field experiments were conducted on no-tillage summer maize over four consecutive years from 2014 to 2017 in a semi-humid and drought-prone region of Northwest China. Four irrigation strategies were used, i.e. rain-fed (RF, no irrigation), conventional flood irrigation (CK), full drip irrigation (FI) and deficit drip irrigation (DI, 75% FI). The results indicated that supplemental irrigation mitigated the drought stress resulting in improving maize growth and a stable, sustainable yield. Plant height, leaf area index and aboveground biomass of the DI treatment were lower than those of the CK and FI treatments, while the DI treatment produced insignificantly lower grain yield and increased grain nitrogen content. The DI treatment promoted the transfer of nutrients from vegetative organs to reproductive organs. The IWUE of the DI treatment was increased by 22.1%–27.3% and 28.4%–48.6% compared with the CK and FI treatments during the four growing seasons, respectively. Soil NO 3 −-N of the CK treatment was mainly distributed below 40 cm soil depth, while most soil NO 3 −-N remained above 40 cm in the FI and DI treatments, implying lower levels of nitrate leaching compared with the conventional flood irrigation. In conclusion, deficit drip supplementary irrigation is a sustainable agricultural production strategy that improves water use efficiency, maintains stable yield and alleviates the risk of soil nitrate pollution in the no-tillage agrisystem of arid and semi-arid regions. Image 1 • Deficit drip irrigation increased IWUE by 22.1–27.3% and 28.4–48.6% compared with flood and full drip irrigation. • Deficit drip irrigation promotes nutrients transfer to reproductive organs and increases grain N content. • Possibility of NO 3 −-N leaching under drip irrigation management was smaller than that of flood irrigation. • Deficit drip irrigation saved irrigation water and did not significantly reduce maize yield. [ABSTRACT FROM AUTHOR]