Abstract:
The effect of competitive stress was studied in two key grass species, Athephora pubescens Nees ecotype VH20 and Eragrostis curvula (Schrad.) Nees cultivar Ermelo. Increasing competition resulted in a decrease in the total yield per plant in both species. Eragrostis curvula proved to be the superior competitor, while A. pubescens was evidently an inferior competitor exhibiting high sensitivity to both forms of competitive interference. Both intra - and interspecific competition failed to have a significant effect on the pattern of biomass allocation to the vegetative organs in both species, while reproductive allocation was absent. A decrease in net co2 uptake rate per unit leaf area, exhibited by both species, coincided with a decrease in leaf production per plant. Increasing competition resulted in retarded relative growth rates and restricted morphological development. A field survey conducted in a natural plant community did not support the findings made of A. pubescens in the pot trials.
