Experimental study on radiation utilization efficiency and soil temperature in paddy field with different irrigation methods in Northeast China

In order to investigate the radiation utilization efficiency and soil temperature with different irrigation methods in cold region and black glebe, northeast, China, three irrigation methods namely control irrigation (CI), wet irrigation (WI) and flood irrigation (FI) were carried out in the field conditions. The radiation utilization efficiency (RUE) and soil temperature with different irrigation methods were analyzed. The results demonstrated that the chlorophyll content (SPAD) was higher in CI plot than in WI and FI plots, while the dry biomass increase (ΔD) and leaf area index (LAI) in CI plot were lower as compared to WI and FI plots. Among the three irrigation methods, FI had the best value of RUE and approached its highest value at the heading stage during the two seasons. The lowest light interception was obtained in CI regime. The soil temperature of 5 cm and 10 cm in CI plot was greater than in WI and FI plots. By contrast, soil heat dissipation and heating quickly while water absorbed more slowly, leading to a large temperature difference between day and night in CI plot, a small temperature difference between day and night in WI and FI plots. Therefore, in cold region and black glebe, northeast, China, with CI method, it could increase the surface soil temperature but the rice growth was restricted. Conversely, FI plot had much advantage in cold region and black glebe, northeast, China.