Manipulation of the irrigation schedule of rice (Oryza sativa L.) as a means of maximizing water use efficiency and irrigation efficiency in the semi-arid tropics

The effect of manipulating irrigation schedule on grain yield, water use ef ficiency and irrigation efficiency of rice (Oryza Sativa L.) was investigat ed. Significantly higher grain yield was obtained with an irrigation schedu led which maintained the soil moisture regime at saturation rather than at submergence or field capacity. Lowest yield was obtained with irrigation sc heduled at field capacity. Water use efficiency followed the same trend as grain yield, however it was lowest at submergence. Irrigation efficiency wa s significantly higher with the saturation regime than with the submergence and field capacity regimes. The submergence regime had the lowest irrigati on efficiency. Only 37% and 40% of the water used in maintaining the submer gence regime was used to maintain the saturation and field capacity regimes , respectively. (C) 1998 Academic Press.