Abstract
A 2-year experiment was conducted using 84 cylindrical metal barrels, each 80 cm in diameter and 120 cm in height. Barrels were packed with sandy loam soil to evaluate the effect of three subsurface water levels (30, 70, and 100 cm) and four irrigation intervals (daily, every second day, every third day, and every fourth day) in a completely randomized design on growth and production of Hassawi rice (Oryza sativa L.) cultivar. The 30-cm subsurface water level (SW L) gave the highest grain yield. However, yield decreased as SW L increased. On the other hand, the four irrigation intervals showed significant increase in grain yield as the frequency of irrigation decreased. All yield components were positively affected by increasing irrigation frequency. The most important was found to be the 100-grain weight. The increase in grain yield was associated with the increase in plant height, plant fresh weight, plant dry weight, and weight of 100 grains. The interaction between SW L and irrigation intervals revealed that the highest grain yield was obtained at 30-cm SW L and daily irrigation. However, the grain yield obtained at 30-cm SW L and irrigation every second day showed similar yield and higher water use efficiency, with a savings of 12% irrigation water compared to that used at daily irrigation and 30-cm SW L. All other combinations of SW L and irrigation intervals either produced very low grain yields or showed low water use efficiency. Therefore irrigation of Hassawi rice in sandy loam soil may benefit from shallow SW L (30 cm) and irrigation every second day, which may prove to be an acceptable management practice for grain rice production, providing the highest water use efficiency.