施氮水平和收获时期对夏玉米产量和籽粒品质的影响

为明确黄淮海夏玉米适宜的施肥量和最佳收获时期，设计了5个氮肥水平（不施肥、113、181、249和375 kg N·hm^-2）和2个收获时期（S₁：9月23日，农民习惯收获时间；S₂：9月29日，推迟6 d收获），研究施氮量和收获时期对夏玉米产量和品质的影响.结果表明：随施肥量增加，夏玉米穗粒数、千粒重和产量均增加，但差异不显著，其中施肥量在113～181 kg N·hm^-2的玉米产量、氮素利用效率均相对较高；随施肥量增加，夏玉米蛋白质和赖氨酸含量增加，淀粉含量降低.与9月23日蜡熟期收获相比，9月29日完熟期收获的夏玉米籽粒千粒重、产量、淀粉和赖氨酸含量均增加，籽粒蛋白质和脂肪含量降低.依据产量水平，黄淮海高产夏玉米区适宜的施肥量在113～180 kg N·hm^-2，最佳收获时期应推迟至9月29日-10月5日.

Effects of nitrogen fertilization rate and harvest time on summer maize grain yield and its quality

In order to approach the optimal nitrogen fertilization rate and suitable harvest time for the high grain yield and quality of summer maize in Huanghe Haihe Area, a field experiment with five nitrogen fertilization rates (0, 113,181, 249, and 375 kg N·hm^-2) and two harvest time (S₁: September 23, conventional harvest time for local farmers, and S₂: September 29, 6 days delayed) was conducted. The results showed that the kernel number, grain yield, and 1000-grain mass increased with nitrogen fertilization rate, but the differences were not significant. With increasing nitrogen fertilization rate, the protein and lysine contents of the grains increased, while the starch content decreased. After 6 days delayed for harvest, the grain yield, 1000-grain mass, and the starch and lysine contents of the grains increased, but the protein and crude fat contents decreased. Based on the yield level, the optimal nitrogen fertilization rate for the summer maize in Huanghe-Haihe Area was 113-180 kg N·hm^-2, and the suitable harvest time was from September 29 to October 5.