Improving wheat yield, quality and resource utilization efficiency through nitrogen management based on micro-sprinkler irrigation

Water resources shortage and unreasonable application of nitrogen fertilizer has been a problem in the wheat production of North China Plain, it is crucial to further increase wheat grain yield, quality, and resource use efficiency under limited water and nitrogen supply. The aim of this study was to determine a nitrogen application mode to simultaneously improve wheat grain yield, quality, water and nitrogen use efficiency, and clarify its enhancement mechanism. A field experiment was conducted during the growing season of winter wheat in 2018-2021. Under the total nitrogen application rate of 210 kg ha(-1), three nitrogen base to topdressing ratios were set as B1 (3:7), B2 (5:5) and B3 (7:3), respectively. Carbon and nitrogen metabolism characteristics of winter wheat was measured, additionally, water and nitrogen use were explored. Results showed that increasing the ratio of nitrogen topdressing (B1 and B2) significantly improved the chlorophyll content, net photosynthetic rate, glutamine synthetase activity, nitrate reductase activity and soluble protein content during grain filling. On average, compared with B3 treatment, 1000-grain weight and total protein content in B1 were significantly increased by 7.6 % and 48.6 %, and those in B2 were significantly increased by 4.5 % and 4.5 %, respectively. Compared with B1 and B3 treatments, the spike number and grain weight under B2 treatment were the most harmonious, and the yield increased by 3.7 % and 5.7 %, respectively. Additionally, B2 treatment significantly enhanced soil water consumption, decreased NO3-N accumulation, finally increased water and nitrogen use efficiency. In summary, when the total nitrogen application rate was 210 kg ha(-1) under the micro-sprinkler irrigation, optimizing the ratio of base to topdressing of nitrogen fertilizer (5:5) could coordinate the post-anthesis carbon and nitrogen metabolism, and synergistically improve the grain yield, protein content as well as water and nitrogen use efficiency of winter wheat.