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The integrated management of water and fertilizer has been widely applied for effectively utilizing limited rainwater resources in rainfed farming systems. However, the combined effect of straw mulching and urea blended with slow-release nitrogen fertilizer (SU) on rainfed maize has seldom been studied. A two-year field experiment (2016–2017) was conducted to evaluate the effects of various agronomic practices, i.e. wheat straw mulching over the entire soil surface (QSU), wheat straw mulching over the partial soil surface (DSU), and water-retaining agent (BSU) under two N application rates (N1: 120 kg ha−1 and N2: 180 kg ha−1) on rainfed maize in northwest China. The results showed that DSUN2 delayed leaf senescence, increased chlorophyll content and photosynthesis, promoted N uptake, and increased grain yield (GY) (by 19.34%-39.91% in 2016 and 11.00%-52.57% in 2017), water use efficiency (WUE) (by 14.35%-56.21% in 2016 and 8.87%-57.44% in 2017) and nitrogen use efficiency (NUE) (by 12.03%-31.82% in 2016 and 0.49%-9.34% in 2017). More soil water was retained by QSU, which significantly promoted maize growth, but decreased GY compared with DSU. In conclusion, DSUN2 was the most effective agricultural management practice for improving GY, WUE and NUE of rained maize in northwest China. [ABSTRACT FROM AUTHOR]

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]