中文摘要：

以郑单958（ZD958）和登海661（DH661）为试材，比较研究了4．5、7．5和10．5万株hm^-2三个种植密度下，雌穗分化与籽粒发育及败育的关系。结果表明，密度对玉米雌穗原基开始分化的时间无影响（不同密度下，穗原基均在播后28～29d左右开始分化），对吐丝期分化的小花总数影响很小。但是高密度推迟了雌穗的分化进程，增加了败育花和未受精花的数目，导致正常成熟小花数目的降低。与低密度相比，高密度下DH661正常小花数减少了100．0个，ZD958减少了76．4个。高密度加大了雌雄穗吐丝开花间隔，降低了吐丝植株的比例（DH661吐丝植株占93．64％；ZD958的占81．80％），推迟了吐丝时间，使单株吐丝量减少，散粉持续时间缩短，导致败育增加。正常受精的小花在灌浆期也会发生籽粒败育，尤其是在花后10d左右败育严重。相关分析表明，玉米最终的穗粒数与开花期以及花后10d、20d的冠层底部透光率相关性显著，花败育率与开花前冠层底部透光率显著负相关。

英文摘要：

Two cultivars ZD958 and DH661 were used to analyze the effect of different planting densities （45 000 plant ha1, 75 000 plant ha^-1, 10 5000 plant ha^-1） on kernel development and barrenness in maize （Zea mays L.）. The results showed that increasing plant density had little effects on the time of ear primordia differentiation （the ear primordia presented at 28-29 days after sowing under different densities） and the total number of floret primordia during silking. However, the differentiation of ear was postponed under high density, the number of abortive florets and unfertilized fiorets increased with the increase of plant den-sity. Compared with low-density, the high density reduced number of normal fiorets per ear by 100.0 for DH661 and by 76.4 for ZD958. Additionally, the anthesis-silking interval （ASI） was elongated, the ratio of the silked-plants was decreased （ratio of DH661 was 93.64% and that of ZD958 was 81.80% under high density）, the time of silking was delayed, the number of silked florets per ear was reduced and the pollen shedding duration was shortened with increasing plant density, which results in the in- crement of abortion after fertilization. Interestingly, kernel abortion would also occur during grain-filling, especially in 10 days after anthesis. The kernel number per ear had a positive correlation with the bottom transmittance at silking, 10 d after silking and 20 d after silking, while the ratio of abortive floret was negatively correlated with the bottom transmittance before flowering sig-nificantly.