Maize root morphology, distribution, and effective rooting depth under contrasting soil water availability

Aims: To evaluate the effect of differential irrigation management on the growth, depth distribution, and morphology of the maize root system, and how these factors influence vegetative and grain productivity. Methods: A field experiment was conducted under rainfed and irrigated conditions in soil with acidic pH and increasing penetration resistance with depth. Grain yield, shoot dry matter, soil properties, and root attributes were measured. Root samples were collected at four soil depths (0–10, 10–20, 20–30, and 30–40 cm), and root morphology and distribution were quantified using image-based analysis. Results: Rainfed conditions promoted greater root allocation at intermediate depths, particularly at 20–30 cm, whereas irrigation increased root concentration in the surface layer (0–10 cm). In both treatments, root development below 30 cm was limited by combined physical and chemical soil constraints. Irrigation increased shoot biomass and grain yield, reflecting improved water availability in layers with higher root activity. Conclusions: Soil water availability modifies maize root distribution within the soil profile and interacts with soil constraints to define effective rooting depth. These results highlight the importance of incorporating root distribution and soil limitations into irrigation scheduling and soil management strategies in intensive maize systems.