Effects of plant density on nitrogen metabolism and nitrogen use efficiency of late sown winter wheat in Yellow and Huai Valley in China.

[Objective] Effects of plant density on nitrogen metabolism and nitrogen use efficiency of late sown winter wheat were studied to provide a basis for high-yield and efficient use of nitrogen fertilizer of late sown winter wheat in Yellow and Huai Valley in China.[Method] We conducted an experiment to study the effects of plant density on nitrogen metabolism and nitrogen use efficiency of late sown winter wheat in 2007-2008.[Result] The results showed that,compared with normal sowing(October 15),late sowing(October 26) enhanced the activity of nitrate reductase and the soluble protein content in flag leaf.However,the nitrogen accumulation amount of whole plant,nitrogen concentration of grain,grain yield and nitrogen use efficiency of that were reduced because of shorter growing period.Under the condition of late sowing,the activity of nitrate reductase,glutamine synthetase,the soluble protein content in flag leaf was higher under medium plant density(225×104 plants/hm2) and high plant densities(300×104 plants/hm2) than that under low density,so were the leaf nitrogen content,the contribution of translocation nitrogen to grain nitrogen accumulation.Thus,grain yield and nitrogen use efficiency under medium and high plant densities(300×104 plants/hm2) were higher than that under low density.[Conclusion] In the areas with the condition similar to this experiment,when considering both yield and grain quality,Xinmai 18 is suggested with the densities 225×104 plants/hm2 for moderate late sowing.