Understanding of maize root responses to changes in water status induced by plastic film mulching cultivation on the Loess Plateau, China

Water stress is the most important factor limiting crop production in arid and semiarid regions. Cultivating crops using a plastic film mulch can significantly increase crop yields by optimizing soil hydrothermal conditions in semiarid agroecosystems. Therefore, clarifying root adaptability to plastic film mulch cultivation is crucial when attempting to produce stable and high maize yields. A two-year experiment was conducted to investigate the effects of two treatments, no mulching (NM) and plastic film mulching (FM), on the yield, water productivity (WP), and root morphology of spring maize on the Loess Plateau. The results showed that the FM yield (14.31-15.02 t ha-1) significantly increased by 18.6-29.7 % compared to NM (11.03-12.66 t ha-1). The FM treatment also significantly increased dry matter (51.0-61.6 %), leaf area (19.7-25.7 %), and WP (28.8-46.3 %), but decreased ET (8.6-12.8 %). In addition, soil water storage in the FM surface soil layer significantly increased compared to that of NM. Film mulching also produced more robust roots and promoted the convergence of roots towards the surface of the soil, whereas NM roots tended to grow downwards to obtain water from the lower soil layers. The regression analyses indicated that root length (R2 = 0.725, P < 0.01) and biomass (R2 = 0.736, P < 0.01) were positively correlated with grain yield. The results suggested that maize adapts to changes in root morphological behavior under FM. These changes contribute to soil water and nutrient capture and shoot development, which subsequently support the high yields produced under plastic film mulching. Therefore, film mulching is a promising strategy for improving yield and WP and for optimizing root morphology in dryland agriculture.