EFFECT OF AUTUMN CUTTING REGIME ON DEVELOPMENTAL MORPHOLOGY AND SPRING GROWTH OF PERENNIAL RYEGRASS

Two field experiments were conducted at Aberystwyth on simulated swards of S. 23 perennial ryegrass which were cut one or more times between August and January. The further effect of cutting in early spring was also examined. The weight of harvestable herbage produced in spring was found to be much less from plots which had been cut frequently in autumn and winter, and was also reduced when the final cutting date was progressively delayed. The principal effect of later and more frequent cutting in autumn on developmental morphology was a dramatic reduction in the length of leaves produced subsequently. This effect persisted well into the spring period. Numbers of tillers and leaves were much less affected. Thus a greater bulk of herbage was present in spring on autumn-rested swards. Production of new tillers in spring was, however, encouraged by greater levels of prior utilization, including cutting in March. Total herbage yields from the different defoliation systems up to and including different harvesting dates in spring were very similar, but contained a higher percentage of dead material when autumn growth had been allowed to accumulate for longer periods. Under these systems considerable numbers of leaves were formed but died without being harvested. Tiller survival at low temperatures was poorer in swards left undefoliated after the end of August. © 1979, Cambridge University Press. All rights reserved.