Some aspects of competition between pasture species: the effect of environment and defoliation.
See also Abs. 804. A series of glasshouse, growth room and field experiments were designed to study interference between perennial ryegrass [Lolium perenne] cv. PRG S23 and ribgrass (Plantago lanceolata). Pure stands and 1: 1 and various mixtures of each species were sown at a density of 12 plants/17.75-cm diam. pot in the glasshouse. The effect of cutting ±N fertilizer application on a mixed sward was investigated in the field. Mean plant weights of ryegrass exceeded those of ribgrass 2 weeks after emergence in pots. Close cutting slightly increased ribgrass yields in the field but its population size was controlled by the rapid regrowth of its associates (ryegrass and clover) which exerted intense competition. Factors enhancing the growth of grass species (fertilizers, onset of reproductive growth) reduced the potential yield of associated species in spring and summer.-P.K.