Effects of Planting Date and Density on Grain Filling Process of Summer Corn(Zea mays L. ) in Yanhuai Flood Storage Area

[Objective] The aim was to understand effects of planting date and density on grain yield and filling process of summer corn in Yanhuai flood storage area. [Method]Effects of two different planting dates and four different planting densities on grain yield and filling process of summer corn in Yanhuai flood storage area were examined. [Result]The duration of grain filling period of early sowing( Jun 15) was longer than that of late sowing( Jun 25); the duration of slight-increase period was shorten; and the duration of fast-increase period and slow-increase period were increased. The duration of grain filling period was about 60 days,and the best harvest date was about early October. With the postponement of planting date,the greatest potential of grain yield decreased,the active grain-filling period shorted,the slight-increase period,the maximum of filling rate and the mean filling rate increased. The single kernel weight was mainly caused by the rate of slight-increase period and the active grain-filling period between different planting dates. The difference of grain yields between different planting densities was affected by the duration of fast-increase period and slow-increase period. [Conclusion] The results provide theoretical basis for improving yield and quality of corn.