Irrigation regimes affect early root development, shoot growth and yields of maize (Zea mays L.) in tropical minor seasons.

Moisture stress is an important factor affecting field-grown maize in the tropics, especially in the minor dry seasons, and irrigation is required for successful crop growth and yields. Field experiments evaluated the impact of four irrigation regimes ranging from 3 to 21-day intervals on growth of maize (Zea mays L.) roots and shoots at critical stages and on seed yields when compared to those of irrigated maize plants in two minor seasons at Sri Lanka. While surface wetting at planting induced germination in all treatments, growth of seminal and first-order lateral roots was enhanced by increasing irrigation intervals. Relative water contents were similar at irrigation intervals of 3, 7 and 14 days and declined thereafter. At anthesis, root length and weight densities indicated the greater penetration into soil layers with increasing intervals of water supply. The highest yields were at 7 and 14-day irrigation intervals thus illustrating that regular water supply in minor dry seasons may be detrimental for maize growth and yields