大气NH3浓度升高和施氮对冬小麦生物量和氮素利用的影响

为揭示大气NH₃浓度升高和施氮对冬小麦生物量和氮素利用的影响，通过开顶式气室，以小偃22为试验材料，于2020-2022两年进行田间微区试验，设置3个施氮水平（0、180和240 kg·hm^-2）和两种大气NH₃浓度（空气背景NH₃浓度:0.01~0.03 mg·m^-3;高NH₃浓度:0.30~0.60 mg·m^-3）,对不同处理下小麦地上部和根系干物质、氮素积累量及氮素利用效率进行分析。结果表明，大气NH₃浓度升高能显著提升小麦地上部生物量、根系生物量、地上部氮素积累量和根系氮素积累量，2年内平均增幅分别为5.77%、6.74%、8.94%和9.98%。在空气背景NH₃浓度下，施氮后小麦显著增产， 180和240 kg·hm^-2施氮水平下产量较0 kg·hm^-2施氮水平分别提高了45.26%和50.67%。在大气NH₃浓度升高环境中，随着施氮量的增加，小麦产量出现先升后降趋势， 180 kg·hm^-2施氮水平下产量最高， 240 kg·hm^-2施氮水平下小麦产量较0 kg·hm^-2施氮水平降低17.97%，小麦氮肥农学效率和氮素利用率也随之降低。这说明，大气NH₃浓度升高的环境中适当减少氮肥施用量能有效提升冬小麦的氮素利用率，稳定小麦产量。

Effects of Elevated Atmospheric NH3 Concentration and Nitrogen Application on Biomass and Nitrogen Utilization of Winter Wheat

In order to reveal the effects of elevated atmospheric NH₃ concentration and different nitrogen application on the biomass and nitrogen utilization of winter wheat, a field micro-experiment was conducted in 2020-2022 with Xiaoyan 22 as experimental material in an open top chamber. Two factors were set up at different nitrogen application levels (0 kg·hm^-2, 180 kg·hm^-2, and 240 kg·hm^-2) and atmospheric NH₃ concentration (air background NH₃ concentration: 0.01-0.03 mg·m^-3, AM; high NH₃ concentration: 0.30-0.60 mg·m^-3, EAM). The biomass and nitrogen accumulation in shoot and root, and nitrogen use efficiency of wheat were measured and analysed under different treatments. The results showed that the increase of atmospheric NH₃ concentration significantly increased the shoot biomass, root biomass, shoot nitrogen accumulation, and root nitrogen accumulation of wheat, which were 5.77%, 6.74%, 8.94%, and 9.98% higher than the background NH₃ concentration in two years. Under the air background NH₃ concentration, the wheat yield increased with the increase of nitrogen application rate. The treatment of 180 kg·hm^-2 and 240 kg·hm^-2 nitrogen application significantly increased yield by 45.26% and 50.67% respectively in two years. Under the high NH₃ concentration, with the increase of nitrogen application rate, the wheat yield first increased and then decreased. The yield of wheat was the highest under the 180 kg·hm^-2 nitrogen application; the yield of wheat was significantly reduced by 17.97% under the 240 kg·hm^-2 nitrogen application, and the agronomic efficiency and nitrogen utilization efficiency of wheat nitrogen fertilizer also decreased. This shows that reducing the application of nitrogen fertilizer and maintaining the level of nitrogen fertilizer at 180 kg·hm^-2 in the environment with elevated atmospheric NH₃ concentration can effectively improve the nitrogen utilization efficiency of winter wheat and stabilize wheat yield.