Enhancing spatial and temporal coordination of soil water and root growth to improve maize (Zea mays L.) yield

Enhancing the spatial and temporal coordination between soil water and roots is very important for crop growth. The vertical distribution and relationship between soil water and root are however poorly understood during maize growth under different soil water conditions. In this study, two maize hybrids ZD958 and FM985 were treated with drip irrigation (DI), flood irrigation (FI), and rainfed (RF) in two–year field experiment as well as with irrigation at 0–30 (TI), 30–60 (MI), 60–90 (BI), 0–90 cm soil layers (AI) and no irrigation in three–year tube experiment. In field experiment, DI and FI both increased root dry weight, root length density (RLD), and the proportion of coarse root length at different soil layers relative to RF. DI increased grain yield by 10.0% in FM985 and by 10.8% in ZD958 compared with FI. Both total root and fine root length were greater in DI than in FI, which increased the nitrogen and water use efficiency and yield. In the tube experiment, irrigation at different soil layers increased root dry weight, RLD and the proportion of coarse root length compared with no irrigation, with AI increasing the most. FM985 distributed more roots at the 0–30 cm soil layer than ZD958. Grain yields were positively correlated with the RLD in each soil layer and coarse root proportion at the upper layer (r=0.493** in field experiment and r=426** in tube experiment) but negatively correlated with root–shoot ratio (r=−0.793** in field experiment and r=−670** in tube experiment) at maturity stage. In conclusion, there is a large potential to improve maize yield by enhancing the spatial coordination between root distribution and soil water movement.