化控条件下密度对夏玉米产量及产量性状的影响

品种、密度、化控剂三因素试验表明，密度是影响玉米产量的主要因素，化控条件下，不同类型玉米品种产量随密度的增加均呈先增后减的趋势。郑单958适宜密度75 000～82 500株/hm²，先玉335为67 500～75 000株/hm²，化控剂的使用并不能改变品种的适宜密度；化控条件下穗长、穗粗、行粒数与密度呈负相关，秃尖长与密度呈正相关；先玉335穗行数、千粒重随密度增加而减少，郑单958穗行数、千粒重随密度增加先增后减；化控条件下，随密度的增加穗位高增高、植株重心高度先增后降；先玉335株高降低，郑单958株高先增后降。化控剂可有效降低穗位高、植株重心、株高，降低穗位高进而降低植株重心高度增强抗倒能力是密植稳产关键因素。

Effect of Density on Summer Maize Yield and Yield Traits under Chemical Regulation

Three factor tests with variety, density and chemical regulator showed that, density was the main factor affecting maize yield. Under the condition of chemical regulation, yields of different types of maizes showed a trend of first increasing and then decreasing with the increase of density. The suitable density for Zhengdan958 was 75 000-82 500 plant/ha, 67 500-75 000 plant/ha for Xianyu335. Using chemical regulators did not change their suitable densities. Under chemical control, ear length, ear diameter and kernels per row showed negative correlation with density,while bald tip length positive relation. With the increase of density rows per ear and 1000-kernal weight of Xianyu335 decreased, while that of Zhengdan958 first increased and then decreased. Under chemical control, with the increase of density, the height of ear position was increased, while the height of gravity was first increased and then decreased, plant height of Xianyu335 was lowered, while which of Zhengdan958 was first increased and then decreased. Using chemical control agents could effectively lowered the ear position, plant gravity and plant height, which could increase lodging resistance ability and grain yield.