密植条件下去叶处理对夏玉米籽粒灌浆及产量的影响
Effects of Leaf Removal on Grain Filling and Yield of Summer Maize under High Density

增加种植密度是当前玉米增产的重要举措之一。然而，随着密度的提高，群体拥挤，叶片之间郁闭遮阴，导致群体中下部叶片光合速率下降，致使籽粒灌浆受阻，粒质量降低，严重限制高密度条件下产量的进一步增加。因此，如何提高密植玉米群体对光能的有效利用，增强群体光合能力进而提升产量成为当前玉米高产栽培的关键问题。2016年在种植密度为82 500株/hm的大田试验条件下，以紧凑型玉米‘郑单958’和半紧凑型玉米‘强盛101’为试验材料，于吐丝后7 d进行不同程度去叶处理，即分别去除顶部1片叶（S1），2片叶（S2），3片叶（S3），4片叶（S4），以不去叶为对照（CK）。结果表明，去叶可显著改善密植玉米群体冠层透光率（LT），去除顶部2片叶（S2）能延缓密植夏玉米冠层中下部叶片的衰老，延长群体LAI高值持续期，同时还有效提高功能叶SPAD值。此外，去除顶部2片叶（S2）还显著增加灌浆中期籽粒的灌浆速率，使收获期粒质量增加，进而表现增产。其中成熟期，‘郑单958’ S2处理较对照增产13.1%，‘强盛101’增产12.7%。可见，去除顶部2片叶（S2）能显著改善籽粒灌浆中后期冠层中下部叶源光照环境，保证籽粒灌浆期间有较高的源叶面积，籽粒灌浆速率得以显著提高，成熟期粒质量得以明显增加，最终收获较高的群体产量。
Increasing the plant density is a crucial method to improve the grain yield. However,with the increase of planting density,the population was crowded and the leaves were shade each other. The photosynthetic rate of the middle and lower leaves of the population decreased,and the grain filling was blocked,the grain filling was poor and the grain mass decreased,which greatly restricted the yield of the maize under high density. Therefore,how to improve the effective utilization of light energy in maize population under high density,and enhance the photosynthetic capacity of the population and increase the yield become the key problem of high yielding cultivation of maize. In this study,the field experiment in the planting density of 82 500 plants per hectare was conducted,the compact corn ‘Zhengdan 958’ and semi-compact corn ‘Qiangsheng 101’ as the test material. Remove the top 1 leaf (S1),top 2 leaves (S2),top 3 leaves (S3) and top 4 leaves (S4) at 7th day after silking,and no leaf removal as control (CK). The results showed that leaf removal could significantly improve the canopy light transmittance (LT) of the maize population,and the removal of the top 2 leaves (S2) could delay the senescence of the middle and lower leaf of the summer maize and prolong the persistence of the population LAI,while also effectively improve the functional leaves SPAD value. In addition,the removal of the top 2 leaves (S2) also significantly increased the grain filling rate in the medium grain filling stage,increasing the grain mass during harvest and then increasing the yield. As in the mature period,the yield of treatment of ‘Zhengdan 958’ S2 increased by 13.1% compared with the control ,and ‘Qiangsheng 101’ increased by 12.7%. It can be seen that removal of the top 2 leaves (S2) can significantly improve the light environment of the middle and lower leaves of the canopy in the later stage of grain filling,ensure a high source leaf area during grain filling,and the grain filling rate can be improved significantly. The