Effects of Nitrogen Application Rate on Dry Matter,Nitrogen Accumulation and Translocation in Rainfed Winter Wheat in Southern Shanxi

A field experiment locating in rainfed area Xiangfen Shanxi was conducted to study the effects of different nitrogen rates on dry matter,nitrogen accumulation and translocation of winter wheat during the two-year experiment period.The results showed that dry matter accumulation annually varied greatly,but mainly occurred after reviving period,which accounted for more than 80% of the maximum dry matter accumulation.Two uptake peaks of nitrogen of winter wheat appeared at seedling stage and during the revival to heading stages period under different treatments,which accounted for 20%～38%and 44%～56% of the total uptake respectively.The dry mater accumulation before and after anthesis and nitrogen accumulation in maturity stage increased significantly with the increasing of N application in the range of N 0～180 kg/hm2,but the biomass and nitrogen accumulation in maturity stage no longer significantly increased when N application rate was over 180 kg/hm2.However,no significant difference was observed on dry matter translocation efficiency and the contribution proportion relative to P rate.The grain nitrogen accumulation from the transfer of the stems and leaves to the grain accounted for 82% to 98% of the grain nitrogen accumulation amount,and only a small portion of nitrogen was fromthe soil.