Influence of acremonium lolii infection in perennial ryegrass on germination, emergence, survival, and growth of white clover

Abstract

Four glasshouse experiments and two field trials were conducted to determine the effects of perennial ryegrass (Lolium perenne L.) infected with Acremonium lolii Latch, Christensen & Samuels on white clover (Trifolium repens L.) germination, emergence, growth, and survival. Under controlled laboratory experiments, ryegrass leachates temporarily inhibited the rate of white clover germination, but did not affect white clover emergence or yield. In glasshouse experiments, the presence of A. lolii did not influence white clover emergence or growth. Emergence of indicator plant species grown in pumice sand substrate which previously grew ‘Ellett’ or ‘Grasslands Nui’ perennial ryegrass was not affected (‘Ellett’) or was enhanced (‘Grasslands Nui’) by the presence of A. lolii. In field trials, A. lolii infection did not significantly affect white clover survival, vigour, or leaves and stolons per plant, when ryegrass tiller densities were similar. Later, when tiller density of A. lolii-free plants decreased there was a strong inverse relationship between ryegrass tiller density and white clover vigour and growth. Radiation penetration to white clover plants was not different as a result of the presence or absence of A. lolii. It is hypothesised that below-ground competition between ryegrass and white clover had the greatest influence on white clover vigour and growth and allelochemicals released by A. lolii had no direct influence on this relationship. © 1992 Taylor & Francis Group, LLC.