INFLUENCE OF NITROGEN-FERTILIZATION, SOIL TYPE AND WATER-STRESS ON PRODUCTION AND WATER-USE EFFICIENCY OF DIGITARIA-ERIANTHA CV IRENE UNDERGREENHOUSE CONDITIONS

The influence of N-fertilization, soil type and water stress on the gr owth rate and water-use efficiency (WUE) of Digitaria eriantha was eva luated in a pot trial at the University of Pretoria. There were five l evels of N, on three soil types and the treatment combinations were re plicated under conditions of sufficient water supply and water stress. It was concluded that N fertilization, at levels higher than 80 kg Na .(-1), had a significant effect on both growth rate and WUE. In the c ase of growth rate, the influence was overshadowed by soil type. Water stress had a severe effect on growth rate, but only at relative high levels of N application was WUE effected. Growth rate and therefore al so WUE, decreased as the season progressed. It would therefore be good policy to scale down or stop irrigation as soon as the crop's growth rate start to decrease.