Plant Growth Substances and the Regulation of Growth Under Drought

Abstract

This paper reviews briefly the effects of water deficits on the synthesis and distribution of plant growth regulators with some emphasis on genotypic variation in synthesis. The effects of abscisic acid on growth and development are also considered and interactions between growth regulators are highlighted. One possible role for a growth regulator in providing a mechanism to regulate physiology, growth and development as a function of water availability is discussed in detail. It is proposed that reduction in root tip turgor will reduce the synthesis and transport of cytokinins in the root tip and that this reduced transport, perhaps combined with drought-induced reduced uptake of nutrients from the soil, will influence the physiology of the shoot independently from any hydraulic influence.