The influence of grass root systems on growth and form of Trifolium repens

Pure swards of the grasses Dactylis glomerata, Holcus lanatus, and Lolium perenne were allowed to grow in boxes in a standard growth medium; one additional set of boxes with no grasses was used as a control. After 43 weeks, all aboveground parts of the grasses were removed by harvesting at 2 cm below ground level. Next, clones of Trifolium repens collected from patches in a pasture dominated by these three grasses were introduced into each of the grass boxes, in all combinations of grass treatment and T. repens origin, and allowed to grow for 16 weeks. Both the site of origin of the T. repens clones and the treatment imposed by the grasses had significant influences on the growth and form of T. repens. Treatment effects were consistent for most characters, and on average, depression of growth was in the following order: Dactylis > Lolium > Holcus > control. This ranking differs from that reported by many other studies where either whole plants or shoot systems alone were used as the treatment effects on T. repens. Key words: interference, growth, morphogenesis, roots, Trifolium repens.