Effects of phosphorus nutrition on P absorption and yields of soybean

A soybean cultivar, Suinong 14, and the sand culture were used to study the effects of phosphorus (P) nutrition levels and without P on P absorption and yield of soybean at different stages. The results show that the promoting role of the higher P nutrition levels on the P concentrations and P absorption of soybean at early and medium stages is obvious, and soybean plant P absorption is increased continually under the increase of P nutrition at the beginning of blooming (R1). When the P level is 51 mg/L, the promoting role of the P nutrition is not obvious at the beginning of seeding (R5). When the P levels are from 21 to 31 mg/L, the P concentrations of leaves and stems are not increased obviously. When the P nutrition level is 31 mg/L, the promoting role on soybean P absorption of the P nutrition is not obvious at the full maturity (R8), and when the P nutrition level is 41 mg/L, the P concentrations of roots are not increased obviously. When the P nutrition level is increased, the soybean yield shows a single peak curve and the yield is the highest when the P nutrition level is 31 mg/L. When the P nutrition level is increased, the kernel number of a plant shows a single peak curve too, and the kernel number is the largest when the P nutrition level is 21 mg/L. When the P nutrition level is the lowest (P1), the kernel number and the node number are the least, while the weight of 100 seed is the largest. Before the beginning seeding of soybean, the P nutrition level is the key factor of forming yield, and after the beginning of seeding, the yield is insensitive to the P nutrition. The node number and kernel number are decreased under no P nutrition during V3～R1 and R1～R5 stages, while the vegetative of plant is not obviously affected, and the yield and P absorption are decreased obviously. The P concentrations of vegetative, pod skin and seed and P absorption of seed are exclusively affected under no P nutrition during R5～R7 stages, while the effect on the yield is not obvious.