Effects of nitrogen fertilizer and genotypes on the nitrogen and phosphorus accumulation of winter wheat grain during grain-filling period in a sub-humid farmland eco-system

A field experiment was carried out in the south part of loess plateau with 632mm annual precipitation and three varieties of winter wheat,“9430”，“Xiaoyan No.6”,“Shang 188”were used as indicating crops to study the effects of nitrogen fertilizer on grain nitrogen and phosphorus accumulation during the grain-filling period. The results show that during the grain-filling period, the grain nitrogen concentration presents a “high-low-high” temporal changing pattern, but the grain phosphorus concentration declines linearly. The final grain nitrogen concentration is coincident with the grain nitrogen concentration during the grain-filling period in six treatments.“Xiaoyan No.6”grain nitrogen concentration is always higher than that of “Shang 188” and “9430”during the grain-filling period. The grain nitrogen accumulation rate is higher than that of phosphorus; especially at the end of the grain-filling period. There is a significant positive relationship between the length of active grain nitrogen accumulation period and the thousand-kernel weight. Increasing grain nitrogen accumulation rate can increase the grain protein content. Genotype has a significant effect on the active grain nitrogen accumulation period and the average nitrogen accumulation rate, but has not any significant effect on the active grain phosphorus accumulation period and the average phosphorus accumulation rate. Although nitrogen application has not any significant effect on the parameters of grain nitrogen and phosphorus accumulation during the grain-filling period, it could increase the grain nitrogen concentration at mature.