Influence of Water Stress on the Mass of Roots of Buffelgrass Selections and on Their Distribution

Abstract

Approximately two thirds of South. Africa is classified as arid or semi-arid. Cenchrus ciliaris (buffelgrass) is well adapted to many of these dry areas and as such can play an important role in the reclamation of degraded rangelands and stabilization of abandoned, or marginal, cropland. Over the past six years the University of Pretoria has been involved in a series of trials to evaluate the relative merits of material from Africa, America, Asia and Australia (Venter et al., 1993; Rethman et al., 1995; Venter & Rethman, 1996). One of the characteristics, for which this material has been screened, is that of drought tolerance. In South Africa, where low precipitation is also characterized by high variability, the ability of plants to exploit both light and episodic heavy precipitation is influenced by the distribution and extent of the root system. In this instance use was made of the opportunity—presented by an investigation to assess the influence of water stress on above ground productivity over a two year period (Venter et al., 1994; Venter et al., 1995)—to make a terminal assessment of the mass and vertical distribution of roots of seven buffelgrass selections.