Interaction of the Coupled Effects of Irrigation Mode and Nitrogen Fertilizer Timing on Rice Yield in Different Regions

The production efficiency of water and nitrogen is affected by irrigation and the nitrogen rate. However, it is unclear whether there is a coupling effect of irrigation mode and the timing of nitrogen fertilizer application on rice. Therefore, a two-year field experiment was conducted at two sites with varying cumulative temperatures from 2018 to 2019. The effects of irrigation mode and nitrogen fertilization timing on rice yield and related physiological parameters were examined in different regions. The results showed that sites with different average temperatures had different coupling effects of water and nitrogen on crop growth. The impact of irrigation mode on yield was greater than that of nitrogen fertilizer timing at the site with a 2800 degrees C annual cumulative temperature (Wanchang). Alternate wetting and drying irrigation increased yield, water production efficiency and nitrogen production efficiency by 8%-10%, 31%-37% and 8%-10%, respectively. In the site with a 2500 degrees C annual cumulative temperature (Longjing), the coupling effect of irrigation method and nitrogen fertilization timing was significant, and continuously flooded irrigation combined with nitrogen fertilizer (40%:30%:20%:10%) improved rice yield and production efficiency by delaying senescence of leaves and increasing dry matter translocation. The results indicate that combining temperature to explore the optimal coupling mode of irrigation and nitrogen is a promising cropping technique to improve crop productivity and production efficiency in northeastern China.