Effects of Sowing Date and Density on Yield and Fat Content of Summer Soybean

[Objective] The research aimed to discuss the suitable combination with sowing date and density for summer soybean with high yield and oil content.[Method] In the field test with high-oil summer soybean variety Ludou 9 as tested materials and 4 sowing date and 4 density treatments,the effects of sowing date and density on yield and fat content of high-oil summer soybean were studied.[Result] With the delay of sowing date,the yield of summer soybean showed a decreasing trend.With the increment of density,the yield of summer soybean showed a trend of first increasing and then decreasing.When sowing date was June 5th and density was 27×104 plants /hm2,the yield of Ludou 9 was highest(3 565.5 kg /hm2).With the delay of sowing date or the increment of density,pod number per plant,grain number per plant,100-grain weight and grain number per pod all showed decreasing trends.Plant height decreased with the delay of sowing date and increased with the increment of density.Node number and branch number of main stem decreased with the delay of sowing date,the effects of node number of main stem by density was smaller and branch number was obviously decreased with the increment of density.When summer soybean was sowed after June 5th or the density was more than 27 ×104 plants/hm2,the fat content of grain was decreased.[Conclusion] Early sowing in suitable period and reasonable planting density were propitious to high yield and oil content of summer soybean.