IMPACT OF PERENNIAL RYEGRASS SEEDING DENSITIES ON WEED EMERGENCE, GROWTH AND DEVELOPMENT

Research was conducted to determine the effect of perennial ryegrass (Lolium perenne) sowing density on weed growth and development. In glasshouse and field experiments, perennial ryegrass was sown at rates of 0, 5, 10, 20, 40 and 80 kg/ha, with 5 kg/haof white clover (Trifolium repens). With increasing seeding density, perennial ryegrass enhanced its competitiveness against all five of the weeds studied, viz. nodding thistle (Carduus nutans), Californian thistle (Cirsium arvense), Scotch thistle (Cirsium vulgare), ragwort (Senecio jacobaea) and hedge mustard (Sisymbrium officinale). In both trials, increases in the perennial ryegrass seeding density did not reduce weed emergence. However, as perennial ryegrass density increased, weed biomass decreased and time to flowering increased