The influence of leaf death on the rate of accumulation of green herbage during pasture regrowth.
Measurements were made of growth and death in spring and autumn in a perennial ryegrass/white clover sward, and by integration of growth and death data an estimate was obtained of absolute levels of productivity throughout the successive stages of regrowth. Initial reductions in the rate of accumulation of green herbage marking the onset of the phase of decreasing growth rate were accounted for by leaf death. When clover was dominant there was an apparent reduction in the rate of overall synthesis as well. This reduction occurred with clover shortly after complete light interception was attained in both seasons. The lack of any similar effect with ryegrass until lodging occurred was attributed to species differences in growth habit and the subsequent effects of intense shading on the lower canopy.-R.B.