Effects of Nitrogen Application on Yield and Canopy Biomass Accumulation and Distribution of Ningdong 11 Wheat

For providing the theory basis of high winter wheat yield in the yellow river ningxia valley(YRNV),using a randomized block design and Ningdong 11 wheat,the effects of different nitrogen levels on photosynthesis product accumulation,translocation and yield were studied.The results showed that different nitrogen levels affected changes of photosynthesis product accumulations in wheat leaves,sheaths and spikes.Total dry matter accumulation maximized at maturity,in the order of N4N3N2N1(N1,N2,N3 and N4 represent 90,180,270 and 360 kg nitrogen fertilizer per hectare respectively),but the order for grain yield was N3N4N2N1.The main reason was that population density in the N4 treatment increased with ineffective tillers,which led to poor ventilation,transparent less,water supply shortage,seed setting rate declined,grains per spike reduction,ultimately,the harvest index decreased.Harvest spike deficiency led to lower yield in the treatment of N1 and N2.Further analysis showed that the grain yield formation was completed by front-flowering dry matter accumulation,operation rate and post-flowering dry matter accumulation.In addition,increasing nitrogen application amount could prolong function period of green leaves and increase the grain filling duration,which was conducive to the formation of photosynthate,but excessive nitrogen resulted in wheat mature delay of 6 days,which was bad for multiple cropping after the harvest of winter wheat,cropping structure adjustment and the farmers' income increased.Therefore,270 kg nitrogen fertilizer per hectare is suitable for winter wheat in high fertility fields in YRNV.