Effects of Sowing Dates on Leaf Development Characteristics of Summer Maize(Zea mays L.)

[Objective] The aim was to explore the material basis of sowing date on influencing maize yield formation.[Method]The effects of sowing dates on maize leaf development characteristics under two densities(60000 and 75000 plants/hm2) were discussed.[Result]With delaying of sowing date,the developing rate of the ear-leaf and the leaf above it were accelerated,their leaf area index decreased significantly after 13-leaf stage,their chlorophyll content reduced at the silking stage and all the later stages.[Conclusion] The changes of leaf development due to sowing dates adjustment is one of the key reason that sowing date influences the maize yield formation,the yield loss of summer maize due to the late sowing reduces by farming activities adjusting timely.