施氮水平对不同种植制度下玉米氮利用及产量和品质的影响

研究了不同施氮量对套作和单作条件下春、夏玉米氮利用以及产量和品质的影响. 结果表明，随着施氮量的增加，单作和套作条件下，春、夏玉米吸氮量显著增加，籽粒产量、生物产量和籽粒蛋白质产量也显著增加.由于春、夏玉米需求的养分种类与形态一致，低氮条件时竞争较激烈，春玉米处于优势地位，但其吸氮量仍低于单作.增加施氮量可以缓解这种竞争，利于玉米的高产优质.施氮量由187.5 kg·hm^-2增至375 kg·hm^-2时，春、夏玉米单作时生物产量平均增加1.717 kg·kg^-1 N，而套作时平均增加12.179 kg·kg^-1 N；春、夏玉米单作时蛋白质产量平均增加0.305 kg·kg^-1 N，而套作时平均增加1.829 kg·kg^-1 N；春夏玉米套作的土地当量比由1.59增加到1.91.与单作相比，春夏玉米套作可显著提高玉米产量和改善品质，增施氮肥有利于套作条件下玉米高产优质潜力的充分发挥.

Effects of N application rate on N utilization,yield and quality of maize under different cropping systems

The study on the effects of N application rate on the N utilization, yield and quality of mono- and inter-cropped spring- and summer-sown maize showed that under both of the cropping systems, the N uptake, grain yield, dry matter accumulation, and grain protein yield of spring- and summer-sown maize were increased with increasing N application rate. Due to the same demand of N nutrition, there was a competition between spring- and summersown maize in inter-cropping system, especially under low level N application. Spring-sown maize was of superiority in inter-cropping system, but its N uptake was still less than that in mono-cropping system. The competition could be offset by increasing N application. When N application increased from 187.5 kg x hm(-2) to 375 kg x hm(-2), the average increment of dry matter yield of mono-cropped spring- and summer-sown maize was 1.717 kg x kg(-1) N, while that of inter-cropped spring- and summer-sown maize was 12.179 kg x kg(-1) N. The average increment of protein yield of mono- and inter-cropped spring- and summer-sown maize was 0.305 kg x kg(-1) N and 1.829 kg x kg(-1) N, respectively, with the land equivalent ratio increased from 1.59 to 1.91. Compared with mono-cropping, inter-cropping spring- and summer-sown maize could get higher yield and higher quality, and this effect was increased with increasing N application rate.