Studies on Suitable Maize Planting Density of Wheat and Maize Intercropping System in Sichuan Hilly Area

A field experiment was carried out to investigate the effect of different plant densities on spring maize green leaf area,dry matter accumulation,root lodging percentage,stalk breaking percentage and grain yield in Sichuan hilly area. The result showed that,the green leaf area per plant and dry matter accumulation per plant of maize were decreased with the increasing plant density,while the LAI and population dry matter accumulation increased,and the responses of population quality was greater than that of individual characteristics to different plant densities. The grain yield increased with the plant density increasing in the range of 5. 25 × 104plants·hm2to 6 × 104plants·hm2,but it decreased after the plant density over 6 × 104plants·hm2because of their significant declining of kernels per ear and 100-grain weight and their increasing root lodging percentage and stalk breaking percentage. The suitable maize planting density of Chengdan 30 in wheat and maize intercropping system in Sichuan hilly area was 5. 25 × 104- 6 × 104plants·hm2. Meanwhile,the optimal population structure index for high grain yield were LAI from 4. 72 to 5. 41 at silking stage,and population dry matter accumulation from 6330. 98 kg·hm2to 6898.80 kg·hm2at silking stage,as well as 16541.33 kg·hm2to 16616. 25 kg·hm2at maturity stage.