Abstract: This research evaluated the effects of planting density and nitrogen fertilizer rate on maize photosynthetic characteristics, yield and yield components under full film double ridge plastic mulch. The research relied on a field experiment that was set up in 2012 at Dingxi, in the Longzhong region. The experiment used a split plot design, with four planting densities as the main plot factor: 45000 (D₁), 52500 (D₂), 60000 (D₃), 67500 plants·ha^-1 (D₄). The sub plot treatment comprised two nitrogen fertilizer rates: 200 (N₂) and 300 kg N·ha^-1 (N₃). It was found that the leaf area index of maize improved with increase in planting density and nitrogen fertilizer rate, while the chlorophyll concentration decreased with increasing planting density. With increased planting density, the photosynthesis rate of maize decreased. Nitrogen fertilizer rates had no significant effect on the photosynthesis of maize. The treatment (D₂N₂) had the highest yield. The grain yield and biomass of D₂ were, respectively, 15.2% and 14.5% higher than D₁, while the grain yield and biomass under N₂ were, respectively, 10.9% and 4.8% higher than those of N₃. There was a significant positive correlation between grain yield and ear number and kernel number, but no significant correlation with hundred-grain weight. Therefore, under double furrow sowing with full film mulch in dryland farming areas of central Gansu, China, a planting density of 52500 plants·ha^-1 and nitrogen fertilizer application of 200 kg N·ha^-1 was found to be optimal for sustainable cultivation of maize. This cultivation regime facilitated leaf photosynthesis, leading to increased numbers of ears and kernels, thus enhancing maize grain yield.

Key words: planting density, nitrogen rates, maize, yield, photosynthetic characteristics