Effects of Planting Density and Nitrogen Application on Yield and Lodging of Mechanized Sowing Summer Maize

The effects of different planting density and nitrogen application on growth characteristics,yield and lodging of mechanized sowing summer maize were investigated in a field experiment in Sichuan hilly area.The results showed that the growth characteristics,yield and lodging were significantly correlated with density.The ear height during vegetative growth stage,leaf area index in the stamen-growing stage,population biomass,effective panicle number had an increasing trend respectively with density increasing.Under density of 7500 plants per hm2,the plant increased barren ratio,number of gain ear,100-kernel weight,and ear length,length of bearing kernel,ear diameter,rows per ear,kernels per row,were reduced compared with 4500 and 6000 plants per hm2.The yield reached an optimum when planting density was 6000 plants per hm2 and nitrogen application was 375 kg·hm2.Stalk breaking was the major form of lodging of summer maize,and it happened in the internode from bottom 5rd to 6th which was significantly affected by density and application levels of nitrogen.The treatment with density of 6000 plants per hm2 and nitrogen application of 375 kg·hm-2 could reduce root lodging percentage and stalk breaking percentage of summer maize.