Effect of N rates on N uptake,transformation and the yield of winter wheat

A two years field experiment was carried out to study the effects of N application on N uptake and accumulation,N transformation,yield and apparent N recovery in winter wheat(Xiao Yan 22) in high productivity field in Guanzhong Plain of Shaanxi province.Four N rates were employed(0,105,210,and 315 kg/hm2).The experiment design was the randomized complete block with four replications,the area each plot was 33.6 m2(6 m5.6 m).70% of N fertilizer and total P(P2O5 96 kg/hm2) and K(K2O 208 kg/hm2) was used as basal fertilizer,and 30% of N fertilizer used as topdressing fertilizer during the growth stage of regreening.The results showed that N fertilization expect over(application) significantly increased grain,straw yield and total N uptake of shoot of winter wheat in maturity.The apparent N recovery of all N treatments was ranged from 34.2% to 38.3%,which decreased slightly with increasing of N application rates.N content in plant was decreased with the growth stages of winter wheat,but N accumulation in the tissue showed an upward tendency.N application rates influenced N uptake of wheat plant significantly,both N content and N accumulation was increased with N rates increasing in the same growth stage.N application promoted N accumulation in grain significantly,among which.69%～87% of N in grain was transferred from vegetative organs.N fertilization also affected N transfer efficiency,which decreased with N rates increasing.The recommendatory N rate for winter wheat should be controlled from 105 to 210 kg/hm2 under the experimental condition.