Effects of nitrogen application on the accumulation and transportation of dry matter and nitrogen in the above-ground organs of wheat in rice-wheat rotation areas.

A field experiment was conducted to study the effect of nitrogen application on accumulation and transportation of nitrogen and dry matter of aboveground organs in wheat and in the lower yangtze region.This experiment used Yangmai 10 as the material,and four nitrogen levels of N1(0 kg/ha),N2(93.75 kg/ha),N3(168.75 kg/ha) and N4(243.75 kg/ha) were set up.The results showed that increasing nitrogen fertilizer could increase leaf area index(LAI) of wheat,but no obvious differences existed between N2 and N3,and increasing nitrogen ferti-lizer did not affect the dynamic change of LAI.With the amount of nitrogen increasing,more dry matter was obtained,and the highest nutrition organ transfer rate was observed in N0,the highest contribution rate to grain were observed in N2.The transfer rate of stem was significantly higher than that of leaf.The increase in the amount of fertilizer increased the accumulated amount of nitrogen in all growing periods of wheat.There were higher residual nitrogen in stem of N3 after harvest,this would reduce nitrogen utilization rate.Increasing nitrogen would increase wheat yield,but no obvious differences existed between N2 and N3.The highest physiological efficiency of nitrogen was observed in N1 and the maximum utilization efficiency of nitrogen fertilizer was in N2.