Nitrogen Fertilizer and Sowing Density Affect Flag Leaf Photosynthetic Characteristics, Grain Yield, and Yield Components of Oat in a Semiarid Region of Northwest China

Oat has been gaining renewed interest due to its role in a healthy human diet, animal feed, and as source of high value compounds with industrial applications. Nitrogen fertilization planting density are two the most important crop management practices that affect formation yield components final oat. A 2 year 3 × 5 factorial field experiment was conducted investigate effects nitrogen (N) fertilizer on flag leaf photosynthetic characteristics, grain yield, under rainfed conditions. The consisted three sowing densities (60, 180, 300 kg·ha−1) five rates (0, 45, 90, 135, 180 kg·ha−1). Results showed significantly (p < 0.05) correlated net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration (Tr), water-use efficiency (WUE), limitation (Ls), chlorophyll content (SPAD value), area index (LAI), panicle length, number spikelets per (NSP), grains (NGP), weight (WGP), 1000-kernel weight. Among components, driven by (NSP) (NGP) at low (or high) N supply, whereas, also an factor for yield. had significant increased then decreased increase fertilizer, while they density. maximum values were observed 90 kg·ha−1 treatment both growing seasons, mainly contributing improved traits (Pn, Gs, Tr, Ls, SPAD, LAI). combination is suitable oat production cool semiarid plateau or other agroecozones similar environmental