Evapotranspiration and water use efficiency of different grass species in the central Orange Free State.

Abstract

Evapotranspiration (Et) and water use efficiency (WUE) were determined for each of seven grass species during the 1986/87 seasons. The highest and lowest mean daily Et of 2, 39 and 1, 66 mm were recorded respectively for Themeda triandra and Sporobolus fimbriatus. Between species, the average Et for the two seasons did not differ significantly. On average the highest and lowest WUE of 7, 83 and 4, 72 kg/ha above-ground phytomass produces for each mm water evapotranspired, were recorded respectively for Cymbopogon plurinodis and Panicum stapfianum. The average WUE of C. plurinodis, Digitaria eriantha and T. triandra was 38% (P < 0, 01) higher than that of the other four species. Under conditions of moisture stress the WUE of the above-mentioned three species was the lowest and that of Eragrostis chloromelas the highest.

Keywords: above-ground phytomass; cymbopogon plurinodis; digitaria eriantha; eragrostis chloromelas; eragrostis lehmanniana; evapotranspiration; grass; grasses; hydraulic non-floating lysimeters; moisture stress; orange free state; panicum stapfianum; phytomass; south africa; sporobolus fimbriatus; themeda triandra; water use efficiency