RESPONSE OF PERENNIAL RYEGRASS VARIETIES TO ANNUAL CHANGES IN SWARD MANAGEMENT

The effect of annually switching sward management between cutting regi mes that simulated rotational grazing and those for forage conservatio n vs. maintaining a constant management regime was studied by testing for ranking-order changes between six perennial ryegrass varieties. To tal dry-matter (DM) yields were found to change in response to an annu al switch in management. When under a conservation management and swit ched in the next year to simulated grazing, all six varieties yielded more in that year than when they were maintained constantly under simu lated grazing. Similarly, when under a simulated grazing management an d switched in the next year to conservation, all six varieties yielded less than when maintained constantly under a conservation management. These yield differences were largely expressed in spring of the year following the management switch. Differences in the ranking order of v arieties were observed between the constant sward management treatment s and the alternating managements. However, in these changes in variet y ranking, no variety was consistently favoured or disadvantaged by th e annual switch in management. Therefore, no clear evidence was produc ed that an alternating management system had any consistent effect on variety ranking and the observed changes were possibly due to the norm al year-to-year variation frequently recorded in variety performance t rials.