不同降水年型施氮量对冬小麦水氮资源利用效率的调控

Nitrogen application rates at rainfall gradients regulate water and nitrogen use efficiency in dryland winter wheat

【目的】研究不同降水年型氮肥用量引起的小麦生育期耗水量、植株氮素积累与运转、产量及效率的变化,为黄土高原旱地冬小麦精准施肥提供理论依据。【方法】于2017—2020年在山西农业大学闻喜试验示范基地开展大田试验,种植制度为冬小麦后夏休闲,一年一熟。3个试验年降水量分别属于正常、干旱和湿润年型。试验设施氮量0、120、150、180、210 kg/hm^(2)5个处理,分析了小麦耗水量、氮素吸收与利用、产量形成及不同降水年型间的差异。【结果】不同降水年型旱地小麦生育期总耗水量均以N 180 kg/hm^(2)最高,且丰水年和欠水年耗水变化率以施N 150~180 kg/hm^(2)最高,平水年则以施N 120~150 kg/hm^(2)最高。与其他施氮处理相比,丰水年施N 180 kg/hm^(2)提高了播种—拔节期植株氮素积累量,显著提高了花前叶片和穗轴+颖壳氮素运转量,平水年和欠水年施N 150 kg/hm^(2)提高了播种—拔节期植株氮素积累量及花前叶片和茎秆+叶鞘氮素运转量。不同降水年型花前植株氮素运转量、成熟期的植株氮素积累量变化率均以N 120~150 kg/hm^(2)最高。与其他施氮处理相比,丰水年施N 180 kg/hm^(2)产量显著提高了8.4%~35.6%,平水年施N 150 kg/hm^(2)产量显著提高8.9%~33.7%,欠水年施N 150 kg/hm^(2)产量显著提高13.4%~48.9%;不同降水年型产量变化率以施N 120~150 kg/hm^(2)最高,且施氮量增加到N 180 kg/hm^(2)时在丰水年仍可增产。丰水年施N 150~180 kg/hm^(2)肥效最高,达14.9 kg/kg,平水年和欠水年均施N 120~150 kg/hm^(2)肥效最高,分别达18.0和15.2 kg/kg;丰水年施N 180 kg/hm^(2)、平水年和欠水年施N 150 kg/hm^(2)均可获得较高的水、氮利用效率和氮肥表观利用率。此外,不同降水年型增加施氮量条件下,产量、水分利用效率均与花前植株氮素运转量呈显著相关关系。【结论】综合考虑氮肥用量氮肥变化量对耗水量、氮素运转量及产量等变化率的影响,丰水年施N 180 kg/hm^(2),平水年和欠水年施N 150 kg/hm^(2)可提高产量、水氮利用效率和氮肥表观利用率,该施氮量为该区域的推荐施肥量。

【Objectives】We investigated the dynamics of water utilization and yield caused by various fertilizer rates under different rainfall patterns, to provide a scientific basis for precision fertilization in winter wheat on the Loess Plateau.【Methods】A field experiment was conducted from 2017 to 2020 in Wenxi Experimental Demonstration Base of Shanxi Agricultural University, Shanxi Province, the planting system was summer fallowwinter wheat. The three experimental years were typically normal, dry, and wet years, respectively. N application levels at 0, 120, 150, 180, or 210 kg/hm~2 were set up(expressed as N0, N120, N150, N180 and N210,respectively). The N absorption, nitrogen and water utilization, yield, and yield components were investigated.The variation in these indices caused by two adjacent N rates was calculated in each year. 【Results】N180significantly increased water consumption of wheat, regardless of precipitation distribution, and the largest variation of water utilization occurred from N 150 kg/hm~2 to 180 kg/hm~2 in wet and dry years, and from N 120kg/hm~2 to 150 kg/hm~2during the normal year. The highest wheat N accumulation from sowing to jointing stage,and the pre-anthesis export of N from leaf and spike + glume were recorded in N180 in wet year, and in N150 in the normal and dry years. The largest variation of export of pre-anthesis accumulated N and the accumulated N at maturity occurred from N 120 kg/hm~2 to 150 kg/hm~2, regardless of precipitation patterns. N180 exhibited the highest yield in wet year, which was 8.4%–35.6% higher than the other N rates;N150 elicited the highest yield in normal and dry years and was 8.9%–33.7% and 13.4%–48.9% higher than the other N rates, respectively.The largest variation of yield occurred from N 120 kg/hm~2 to 150 kg/hm~2, regardless of precipitation. However,the yield continued to increase significantly from N 120 kg/hm~2 to 150 kg/hm~2 in wet year, and the fertilizer efficiency peaked at 14.9 kg/kg at N150–N180 in wet year. While the yield increment from N 120 kg/hm~2 to 150kg/hm~2 became negative in normal and dry year, N180 produced the highest water consumption, N absorption and utilization, and N recovery efficiency in the wet year, and N150 did in normal and dry years. Yield and water use efficiency of wheat were significantly correlated with the export of pre-anthesis accumulated N. 【Conclusions】In Conclusion, considering the effect of N application level and rainfall gradient, N180 increases water and N utilization, and N recovery efficiency in the wet year, and N150 in normal and dry years, which are the optimum N fertilization level for dryland winter wheat on the Loess Plateau.