Linear dependency of winter wheat yield and nitrogen use efficiency on the pre-anthesis temperature in the lower reach of the Yangtze River

Abstract

Global warming is expected to enhance the nitrogen (N) absorption capability of crops, which causes a change in nitrogen fertilizer input. However, the impacts of warming and nitrogen application on crop growth, yield and nitrogen use efficiency (NUE) are still unclear. Here, we conducted a 4-year field experiment of nighttime warming before winter wheat anthesis to explore the response of winter wheat yield to warming and the variation in nitrogen use efficiency under different nitrogen application levels (N150: 150 kg·ha−1, N225: 225 kg·ha−1, and N375: 375 kg·ha−1). The results showed that warming shortened the winter wheat vegetative growth period (VGP) by 8.3 days, while it prolonged the reproductive growth period (RGP) by 6.7 days. However, there was no significant difference in the growth period of winter wheat between nitrogen treatments. Meanwhile, warming increased winter wheat yield by increasing the number of effective spikes and grains per spike. Every 1 °C increase in pre-anthesis temperature increased winter wheat yield by 45.48, 55.78 and 60.88 g·m−2 for the N150, N225 and N375 treatments, respectively. There was no significant difference in yield between the N225 and N375 treatments, but the nitrogen partial factor productivity (PFPN) and the nitrogen utilization efficiency (NUtE) of N225 were significantly higher than those of N375. PFPN and NUtE were positively correlated with pre-anthesis air temperature under different nitrogen treatments. Multiple linear regression showed that a 1.0 °C increase enhanced NUtE by 11.62%, 9.75% and 7.85% for the N150, N225 and N375 treatments, respectively, and enhanced the PFPN by 7.77%, 8.94% and 9.81% respectively. Therefore, we suggest that 225 kg·ha−1 is an appropriate amount of nitrogen application in the lower reach of the Yangtze River under future climate warming.