Response of South African indigenous grass species to drought stress induced by polyethylene glycol (PEG) 6000

Abstract

Degradation in arid and semi-arid regions can be ascribed primarily to environmental conditions such as extreme changes in temperature and erratic rainfall patterns. Seed germination and seedling growth of three grass species ( Anthephora pubescens, Heteropogon contortus and Themeda triandra) indigenous to arid and semi-arid regions of southern Africa were assessed under controlled conditions that simulated drought stress using polyethylene glycol (PEG) 6000. Exposure to water potentials below − 0.3 MPa significantly decreased germination rates and shoot lengths for all three species, despite slight differences in their sensitivities to osmotic stress. More dramatic differences between the species were evident when the effects of water stress on root growth were evaluated. These findings form the basis for future trials involving the use of indigenous grasses in the restoration of rangelands.