EFFECTS OF CUTTING HEIGHT ON THE GROWTH OF LEAVES AND STOLONS IN PERENNIAL RYEGRASS-WHITE CLOVER SWARDS

All combinations of five cutting heights (2, 4, 6, 8 and 10 cm) were compared, for 3 years (1986-88), on field plots sown with a mixture of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) in Wales. The plots were cut at 4-week intervals from April to October each year, A reduction in cutting height reduced the length, width and weight of clover leaflets, petiole length. stolon diameter, the length of stolon internodes and the height of stolons above ground level, but increased the length of clover stolon/m2, the number of stolon nodes/m2 and the proportion of stolon nodes which produced branches. The latter factors out-weighed the former, leading to the inverse relationship between cutting height and the proportion of clover in the sward previously reported (Acuna & Wilman 1993). A reduction in cutting height reduced the following attributes of ryegrass: the height of the shoot apex, the length and width of leaf blades, sheath length, leaf extension rate, the death rate of leaves and the net gain in blade length. Cutting height had little effect on either the thickness of clover leaflets or the rates of leaf emergence in clover and ryegrass.