限水减氮对关中平原冬小麦氮素利用和氮素表观平衡的影响

研究限水减氮对冬小麦产量、氮素利用率和氮素表观平衡的影响,探讨限水减氮管理模式在关中平原冬小麦生产中的可行性,可为实现关中平原灌区冬小麦生产的稳产高效和环境友好发展提供科学依据.本研究于2017-2018和2018-2019年连续2年在陕西杨凌地区进行小麦田间裂区试验,灌水量为主处理,设置两个灌溉水平,1200 m3·...

Effects of water limiting and nitrogen reduction on nitrogen use and apparent balance of winter wheat in the Guanzhong Plain,Northwest China

Effects of water limiting and nitrogen reduction on yield, nitrogen use efficiency and nitrogen apparent balance of wheat were investigated to explore whether it would be feasible to restrict water and reduce nitrogen in wheat production of the Guanzhong Plain and thus to provide scientific supports for yield-stable, high-efficiency, and environment-friendly developments in the irrigated production of winter wheat. Following a split-plot design with two water regimes as the main plots and four N addition rates as sub-plot factors, a field experiment (2017-2019) was conducted in Yangling, Shaanxi. The two water regimes were conventionally irrigating at the rate of 60 mm during the overwinter period and at the jointing stage, respectively (W₂, a conventional practice) and irrigating at a rate of 60 mm during the overwintering period (W₁, a restrictive irrigation practice). The four nitrogen addition rates were 300 kg·hm^-2(N₃₀₀, a conventional N rate), 225 kg·hm^-2 (N₂₂₅, a nitrogen rate of 25% less than the convention), 150 kg·hm^-2(N₁₅₀, a nitrogen rate 50% of less than the convention), and 0 kg·hm^-2(N₀, no nitrogen applied). The decreased irrigation rate and nitrogen rate significantly increased nitrogen content in the plants and grains, yield, N output, nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency, reduced nitrate leaching and N surpluses, and maintained nitrogen balance. With both W₁ and N₁₅₀ adopted, the increased irrigation rate and nitrogen rate did not affect yield and N output of winter wheat in 2017-2019. Plant nitrogen content with both W₁ and N₁₅₀ adopted increased by 0.1%-25.5% and 14.0%-31.6% and the grain nitrogen content increased by 0.1% and 4.6%, compared with those with both W₂ and N₃₀₀ adopted in 2017-2018 and 2018-2019, respectively. Nitrogen use efficiency, nitrogen harvest index, nitrogen recovery efficiency, and nitrogen agronomic efficiency were averagely increased by 95.3%, 4.2%, 81.7% and 33.0% respectively. The N surplus was decreased by 97.2% and 95.1%, which effectively alleviated soil nitrate leaching. Considering all the indicators, irrigating at 600 m³·hm^-2 during the overwintering period plus applying nitrogen at 150 kg·hm^-2 could achieve high yield, high efficiency, and environment friendly development of winter wheat in the Guanzhong Plain of Shaanxi.