Effects of interaction between density and nitrogen on grain yield and nitrogen use efficiency of winter wheat

In order to verify the optimum nitrogen application rate and planting density for higher grain yield and nitrogen use efficiency, and to provide basis for the development of rational cultivation measures, two cultivars ,Tainong18（T18） and Shannong15（S15） representing large and middle ears respectively were used in this study. Under field condition, four regimes of planting density and three nitrogen rates were applied to study the interaction between nitrogen and density on grain yield and nitrogen use efficiency of wheat. The results show that planting density, nitrogen rate and the interaction between them have significant effects on grain yield and yield components of winter wheat. Compared with the nitrogen rates, planting density is a key factor for increasing the grain yield, and for increasing the agronomic efficiency and apparent recovery efficiency of applied N. In this study, taking both grain yield and nitrogen use efficiency into consideration, the appropriate plant density and nitrogen rate of T18 are 102 kg/ha and N 180 kg/ha respectively, while for S15 are 83 kg/ha and N180 kg/ha. Conclusively, we can adjust nitrogen rate and planting density to take advantage of the interaction between them in promoting the uptake and use of nitrogen for high grain yield and in improving nitrogen utilization.