The effect of density on the performance of individual plants in subterranean clover swards

Abstract

A study was made of the growth of individual subterranean clover plants in pure cultures at 4, 16, and 36 plants dm-2. At 20 days there was no difference between plants in any of the treatments. By 41 days significant differences in root weight between densities had developed and these differences extended to top weights, branch numbers, and the rate of leaf formation as the experiment progressed. The effects on individual plants were essentially the outcome of competition for light. At all densities some plants continued to gain weight throughout the experiment while others were suppressed after an initial increase. As competition for light became more severe, variable leaf development led to increasing variation between plants. From 90 days onwards the coefficient of variation of individual top weights and root weights steadily increased at the two higher densities. Those plants that had their developing leaves heavily shaded for a period of time eventually died. The performance of individual plants is discussed in relation to the light microclimate. The experiment leads to the view that dominance and suppression are characteristic, in some degree, of all plant communities.