关键词: 施氮量, 施氮时期, 地上生物量, 氮素吸收利用

Abstract: The amount and method of nitrogen fertilizer application directly affect oat yield and nitrogen use efficiency,which are crucial factors for crop growth and production. To investigate the impact of reduced nitrogen fertilization in different stages on oat biomass and nitrogen use efficiency,this study employed a two-factor experimental design,using Avena sativa L. ‘Qinghai’ as the test material. Three nitrogen application levels (N1:69 kg·hm^-2,conventional nitrogen application rate;N2:51.75 kg·hm^-2;N3:34.5 kg·hm^-2) and two nitrogen application periods (D1:all basal fertilizer;D2:30% basal fertilizer + 70% topdressing during jointing stage) were set up,with no nitrogen fertilizer application during the entire growth period as the control (CK). The study dynamically monitored indicators such as oat aboveground biomass and plant nitrogen content. The results showed that compared with the conventional nitrogen application rate in a single basal application,the strategy of applying 75% nitrogen fertilizer in two stages could significantly increase the aboveground biomass of oats during different growth stages,achieving the optimal yield (14 100.4 kg·hm^-2) during the full maturity stage of oat. In addition,the nitrogen use efficiency and nitrogen contribution rate of the 75% nitrogen fertilizer applied in two stages increased by 26.07% and 4.90%,respectively. Therefore,in the Huangzhong region of Qinghai Province,applying 75% nitrogen fertilizer in two stages can effectively reduce nitrogen loss,improve nitrogen use efficiency,and ultimately achieve nitrogen reduction without yield reduction.

Key words: Nitrogen application, Nitrogen application period, Aboveground biomass, Nitrogen uptake and utilization