F.R. McKENZIE

Department of Grassland Science, University of Natal, Scottsville, Republic of South Africa

Abstract

The vigour of Lolium perenne during its establishment year was evaluated under subtropical conditions. Both plant and individual tiller vigour were monitored under nitrogen (N) applications ranging from 120–720 kg/ha/yr. Plant vigour, as indexed by etiolated growth per unit area, increased with increasing levels of applied N up to 480 kg/ha/yr. Increasing levels of applied N increased tiller density, but reduced individual tiller vigour. Irrespective of treatment effects, vigour in perennial ryegrass under subtropical conditions during the establishment year declines during mid- to late summer.