Effect of forage conservation cut at different phenological stages of perennial ryegrass on the dynamic of ryegrass/white clover sward

Abstract

In Remehue Regional Research Centre (Osorno, Chile) throughout two years (1987/88 and 1988/89) the dry matter yield, botanical composition, population dynamic, regrowth and persistence of perennial ryegrass (Loliumperenne L.) and white clover (Trifolium repetís L.) mixture was evaluated at five different phenological stages of the ryegrass during the spiing-summer period in each year. The five stages were: boot (B), ear emergency (EE), blooming (BL), milky aqueous grain (MAG) and hard mealy grain (HMG) compared to rotational grazing (RG) all around the year. Treatments were grazed with cows after cutting in each development stage. The annual dry matter yield was different between phenological stages of cut management against all year grazing. On the same way, significant difterences (P<0.01) were obtained on B (4,3 ton dry matter/ha) and MAG (9,5 ton din/ ha) and on B (2,5 ton dm/ha) and MAG (6,1 ton dm/ha) in spring-summer 1987/88 and 1988/89, respectively. The dry matter yield was accumulated between 51 and 56 days on B and between 90 and 98 days on MAG, for the first. and second year, respectively. The older phenological stages produced higher accumulated yield at conservation cut. However regrowth and persistence of the sown species were significantly reduced through the years. The perennial ryegrass contribution (% dry matter base) decreased from 83,5 to 38,8% at B stage and from 69,6 to 9,0% at MAG stage between tlie beginning and the end of the experimental period, which shows the easy way to reduce persistence of sown species under conservation cut management when perennial ryegrass/white clover sward is spelled o ver 60 days in spring.