Combined Effect of Plant Density and Nitrogen Input on Grain Yield, Nitrogen Uptake and Utilization of Winter Wheat

Combined Effect of Plant Density and Nitrogen Input on Grain Yield, Nitrogen Uptake and Utilization of Winter Wheat

The nitrogen input and plant density have significant effects on nitrogen uptake and utilization of winter wheat. The objective of this work was to optimize nitrogen input and plant density for higher nitrogen uptake and utilization while maintaining grain yield. Field experiments were performed during the 2011-2012 and 2012-2013 growing seasons using two cultivars under different nitrogen input rates (0,180 and 240 kg ha-1) and plant densities (120, 180 and 240 plants m-2 for Jimai 22 and 135, 270 and 405 plants m-2 for Tainong 18, respectively). The results showed that increasing plant density improved yield and increased nitrogen-use efficiency owing to the increased nitrogen uptake efficiency. The highest plant density at nitrogen input of 180 kg ha-1 obtained equivalent grain yield, and higher nitrogen uptake efficiency and nitrogen utilization efficiency compared with that at 240 kg nitrogen ha-1. Nitrogen-use efficiency positively correlated to nitrogen uptake efficiency at all nitrogen input rates. Negative relationship between nitrogen-use efficiency and nitrogen utilization efficiency was only found at nitrogen input of 240 kg ha-1, indicating that the low nitrogen utilization efficiency limited nitrogen-use efficiency increasing at high nitrogen input.. .