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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]

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]

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]