English

Abstract

The high yield of crops mainly depends on the interaction between nitrogen (N) fertilization and planting density. The present study evaluated the influence of different N application rates and planting density on the yield and N utilization efficiency of direct seeded rape during the 2016–2017 and 2017–2018 growing seasons. The three N application rates including 108 kg N ha−1, 144 kg N ha−1 and 180 kg N ha−1 were laid out into main plots while planting density including 15.0 × 104, 22.5 × 104, 30.0 × 104 and 37.5 × 104 plants ha−1 respectively into sub-plots. The results showed that suitable planting density was the premise to gain high rapeseed yield and the contribution of planting density to rapeseed yield was small when it surpassed a certain value. The highest yield in the two growing seasons was achieved at 144 kg N ha−1 with planting density of 30.0 × 104 plants ha−1. The rapeseed yield increased linearly as N uptake of the seed part increased, but at high planting density, there was no increase in yield with the increase N uptake of non-seed parts (stem + husk) when rapeseed yield exceeded a certain value. High planting densities raised shoot N uptake and N transfer to rapeseed seeds with the increase of density and N utilization efficiency was also improved. The too much N application resulted in more N accumulation in non-seed parts without increasing production. Under the same target yield, the increased planting density can save 32.4–65.7% of N fertilization compared with the conventional planting density. The combination of different N fertilization rates and planting densities is helpful to increase rapeseed yield. The best N management strategy is to achieve high yield and reduce the environmental risk to reduce the N fertilization at suitable high density. © 2022 Friends Science Publishers