Effect Of Different Planting Density On Yield And The Development Of Summer-maize Silks

Contradiction between the reductions of farmland areas and the increase of demands for corn is increasingly fiercer in China. Some measures must be taken to increase the yield, while the scientific determination of the density is crucial to achieve high-yield cultivation of maize. The development process of maize silks must be affected with the change of the density. Therefore, it has not only the important theoretical significance but also the application value of maize high yield to study the effects of different planting density on maize silks.Under different planting density, the silk development and differences of morphological structure of different parts of Zhengdan 958 and Xundan 20 maize ear are studyed. SPSS and DPS softwares are used to analyze the correlation of silk data obtained from quantitative mensuration with density and yield. The results are as follows:The period of silk development delayed accordingly with the increase of density.At early silking stage, the silking number decreased with the increase of density,and the differences reached a significant level among three densities.The growth process of silks showed a typical "S" curve characteristic. For the silks at ear top, the peak value of the silk length appeared in the condition of medium density, and they were almost the same at low and high density; the silk growth speed was the fastest at medium density, it was second at high density and last at low density. For the silks at middle and basal ear,the silks length decreased with the increase of density.At the middle silking stage, the silk growth rate decreased with the increase of density.The growth rate was the latest one reached the peak at high density,and was the earliest one declined at low density.With the increase of density,the number and length of silk hair were decreased, and the stripes became gradually intensive.At medium density, the number of silk hair was the most, the stripes were intensive and the gaps among them were the deepest, it showed that the ability of pollen adhesion increased.The vascular bundles areas of silk reduced with the increase of density on every part of maize ear. The values of silk xylem vessel diameter and phloem areas were maxium on every part of maize ear at medium density. Correlation analysis showed that vascular bundle areas had a significant positive correlation with dry kernels weight of single ear, 1000-kernel weight and kernel numbers of single ear.And the vascular bundle areas had a significant negative correlation with density.The phloem areas had a significant positive correlation with yield.Meanwhile, vessel diameter of xylem had a significant positive correlation with yield.Different planting densities had a great effect on maize yield.The dry kernels weight of single ear and kernel numbers of single ear of Zhengdan 958 and Xundan 20 reduced with the increase of density.The yield showed as follows:medium density >high density >low density.