Effects of planting density on assimilation,accumulation,distribution and use efficiency of nitrogen in late sowing winter wheat

The objective was to study effects of planting density on the assimilation,accumulation and distribution of nitrogen,and its use efficiency for late sowing winter wheat.Three plant densities(150×104,225×104 and 300×104 plants/hm2) were designed in the late sowing dates for the two year's field experiment by using heavy spike type of winter wheat cultivar Lankao Aizao 8 as an experiment variety.The results showed that compared with the traditional early sowing,the flag leaf activity of nitrate reductase(NR) and the content of soluble protein(SP) were remarkably enhanced in the late sowing dates.The accumulation amount of nitrogen per stem,the contribution ratio of nitrogen that nitrogen stored in vegetative organs was translocated to grain,the nitrogen harvest index and nitrogen intaking efficiency in the late sowing dates were higher than that in the traditional early sowing dates,while the nitrogen use efficiency and grain yield were decreased.The activities of nitrogen metabolism enzymes-accumulation amount of nitrogen,nitrogen use efficiency and grain yield in middle density(225×104 plants/hm2) and low density(150×104 plants/hm2) treatments were higher in the traditional early sowing dates,while that in middle density(225×104 plants/hm2) and high density(300×104 plants/hm2) treatments were higher in the late sowing dates.The protein content and yield of middle density treatment were significantly higher than that of the other two densities in both sowing dates.Therefore,when taking both grain yield and efficient nitrogen utilization into consideration,it is suggested that the densities of 225×104 and 300×104 plants/hm2 be adopted in the late sowing for the variety Lankao Aizao 8