Effects of Abscisic Acid and Water Stress on Development and Morphology of Wheat

Abstract

Experiments were conducted to compare the effects of abscisic acid (ABA) and water stress treatments on leaf morphology and floral development in a spring wheat. In one experiment injections of ABA or a control solution were given twice a week into the base of the main stem for a period of 3 weeks. In a similar experiment control plants were watered daily and treated plants were subjected to water stress by watering only once a week. In both experiments the treated plants produced smaller leaves and fewer spikelets per ear. Analysis of epidermal morphology using polystyrene imprints of selected leaf blades from the main stem and a tiller of each plant showed that, compared with control plants, both ABA and water stress decreased the mean cell size, reduced the number of stomata per leaf, and increased the production of trichomes in all the leaves sampled. Data for stomatal lengths and stomatal indices showed differences between a main stem leaf and a tiller leaf which were consistent for both experiments. It is concluded that ABA could mediate many of the responses of wheat plants to prolonged water stress. The possible adaptive value of these responses is discussed.