To explore the effects of nitrogen application and sowing density interaction on the seed yield of ‘Qingyan No.2’ oat （Avena sativa ‘Qingyan No.2’） in the high-altitude area， the optimal planting nitrogen amount and sowing density suitable for the production of ‘Qingyan No.2’ in Huangzhong and its surrounding areas were investigated. This experiment adopted a two-factor randomized block design. Four nitrogen application levels of 0， 45， 90 and 135 kg·hm^-2 （denoted as N₀， N₁， N₂ and N₃） were set， and three sowing densities of 100， 170 and 240 kg·hm^-2 （denoted as S₁， S₂ and S₃） were established. The results showed that the effects of nitrogen application amount， sowing density， and their interaction on agronomic traits and seed yield all reached extremely significant （P<0.01） or significant （P<0.05） levels. Agronomic traits changed significantly with nitrogen application amount and sowing density. The length of the spike， the number of small florets on the main spike， the number of grains on the main spike， the grain weight per spike， and the hundred-grain weight all increased first and then decreased with the increase of nitrogen application amount， and decreased with the increase of sowing density. Seed yield increased first and then decreased with the increase of nitrogen application amount and sowing density， reaching the peak at a nitrogen application amount of 90 kg·hm^-2 and a sowing density of 100 kg·hm^-2. Pearson correlation analysis indicated that seed yield was significantly positively correlated with spike length， the number of small florets on the main spike， the number of grains on the main spike， the grain weight per spike， and the hundred-grain weight. TOPSIS-multi-criteria decision-making model analysis indicated that at a nitrogen application amount of 90 kg·hm^-2 and a sowing density of 100 kg·hm^-2 were the optimal nitrogen application amount and sowing density for ‘Qingyan No.2’ seed production in the study area and similar high-altitude areas.

‘Qingyan No.2’Oats  /  Nitrogen application  /  Sowing density  /  Agronomic characters  /  Seed yield