双重化控对春玉米不同密度群体冠层结构的影响

在大田栽培条件下,以京单28和先玉335为试验材料,设置5个密度梯度,分别于6叶期和9叶期叶面喷施膦酸胆碱合剂(ECK)和聚糠萘合剂(PKN),研究双重化控对春玉米群体冠层结构的影响.结果表明,随密度的增加,叶面积指数(LAI)、平均叶倾角(MTA)、株高、穗位高上升,透光率降低,冠层结构恶化.双重化控显著降低了高密度下(7.5万～10.5万株/hm²)LAI、穗下叶面积百分比,增加了MTA,提高了下层的通风透光性;缩短了穗下节间长,拉伸穗上节间长,改善了中上部的冠层结构;改善了玉米的穗部性状,显著提高了高密度下的玉米产量,京单28和先玉335产量增幅分别为9.76%～13.00%和10.95%～12.08%.研究表明,双重化控使玉米群体冠层结构得到合理优化,通风透光增强,使高密条件下植株个体维持较高的光合生理活性,产量同步提高.

Effect of Plant Growth Regulators on Canopy Structure in Spring Maize under Different Plant Densities

The field experiment was performed to investigate the effects of plant growth regulators on canopy structure in spring maize under different plant densities. The result showed that with the increasing of plant density, the area index, the mean leaf tilt angle, plant height, ear height increased, but the percent transmission decreased sharply under excessive high density, resulting in uneven light distribution within canopy. The plant growth regulators had decreased the area index and the percent of the area under ear, decreased the mean leaf tilt angle under 75 000-105 000 plants/ha, and shorter lengths of internodes under ear and longer lengths of internodes above ear. Therefore, this could obviously improve the light permeating conditions in the lower layers. The yield and yield components were sharply improved under high plant density. The yield of Jingdan28 and Xianyu335 were 9.76%-13.00% and 10.95%-12.08% higher than the control plants. Thus, the plant growth regulators were proved to be useful to give a good foundation for the photosynthesis production and yield increasing.