WATER-USE EFFICIENCY OF CONTROLLED ALTERNATE IRRIGATION ON ROOT-DIVIDED MAIZE PLANTS

A new method of irrigation was designed and tested for its water use e fficiency (WUE). Maize plants were grown in pots with their roots divi ded and established into two or three separated containers of which ir rigation and soil drying were controlled alternately. Results showed t hat when the two halves of the root system were alternatively exposed to a drying soil and a soil with its water content maintained above 55 % or 65% of its field capacity, water consumption was reduced by 34.4- 36.8% and the total biomass production was reduced by only 6-11%, when compared to the well-irrigated plants. Significant increase in WUE, r oot to shoot ratio and stomatal resistance for water diffusion were ob served as a result of such treatment. Leaf transpiration was reduced s ubstantially while the rate of photosynthesis and leaf water content w ere not significantly altered. The results were also compared to root- divided plants of which irrigation was fixed to one container only and showed that a better WUE, root development and distribution, shoot bi omass production were achieved by the alternate drying and rewetting. We conclude that the controlled alternate irrigation (CAI) is an effec tive and water-saving irrigation method and may have the potential to be used in the field. (C) 1998 Elsevier Science B.V. All rights reserv ed.