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 c ompared, for 3 years (1986-88), on field plots sown with a mixture of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium rep ens 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 st olon nodes/m2 and the proportion of stolon nodes which produced branch es. The latter factors out-weighed the former, leading to the inverse relationship between cutting height and the proportion of clover in th e sward previously reported (Acuna & Wilman 1993). A reduction in cutt ing height reduced the following attributes of ryegrass: the height of the shoot apex, the length and width of leaf blades, sheath length, l eaf extension rate, the death rate of leaves and the net gain in blade length. Cutting height had little effect on either the thickness of c lover leaflets or the rates of leaf emergence in clover and ryegrass.