利用北京地区推广的 8个主要玉米杂交种 ,在不施N和施N条件下研究了产量、N累积量及N效率的基因型差异。结果表明 ,在不施N和施N条件下 ,不同品种之间产量的变异幅度分别为 6 2 %、5 7% ;N累积总量的变异幅度则分别为 5 5 %、48%。其中以农大 10 8的产量和N累积总量最高 ,中单 12 0和中单 2号最低。随施N量增加 ,吸收效率和N效率显著下降 ,利用效率则变化不大。在 2个施N水平下 ,N效率基因型差异主要决定于吸收效率 Using the eight main maize hybrids popularized in Beijing, genotypic differences in yield, N accumulation and N efficiency were studied under N and N application conditions. The results showed that the yield variability of different cultivars was 62% and 57% under N and N treatments, respectively. The variation of N accumulation was 55% and 48% respectively. Among them, the output and N cumulative total of Nongda 108 were the highest, the lowest among Zhongdan 12 and Zhongdan 2. With the application of N increased, the absorption efficiency and N efficiency decreased significantly, while the utilization efficiency changed little. Under the two N application levels, the difference in N efficiency genotypes was mainly determined by absorption efficiency