Optimal Planting Density of New High Protein Summer Soybean Varieties in Huang-Huai-Hai Region

In order to determine the optimal planting density of new high-protein summer soybean varieties in Huang-Huai-Hai region and provide theoretical basis for their popularization and utilization, we used new high-protein summer soybean varieties Shengdou 18, Shengdou 24, Hedou 37 and Hedou 38 as test materials, and studied the effects of planting density on the agronomic traits, seed quality, yield and yield components. The results showed that the plant height and pod height of new high protein summer soybean varieties increased with the increasing of planting density, the effective pods number per plant, the seed number per plant, the dry weight of root, stem and pod per plant and 100-seed weight decreased with the increasing of density, while its effects on main stem node number, effective branch number, seed protein and fat content were not significant. The dry weight of group root, stem and pod of Shengdou 18 and Shengdou 24 were higher with the planting density of 19.5×10~4-22.5×10~4 plants per hectare, while those of Hedou 37 and Hedou 38 had the highest with the planting density of 19.5×10~4 plants per hectare. The highest yield of Shengdou 18 was 3 750.00 kg·ha^-1 under the planting density of 22.5×10~4 plants per hectare, and the highest yield of Shengdou 24, Hedou 37 and Hedou 38 was 3 458.65, 2 952.30 and 3 625.70 kg·ha^-1 respectively under the planting density of 19.5×10~4 plants per hectare.