Competition between perennial rye-grass, meadow fescue and their natural hybrid: variation in growth rates and in the proportion of each species with time.
Growth rate of a triploid [festucoid] natural hybrid between perennial ryegrass and meadow fescue [Festulolium loliaceum]was compared with that of the 2 parent species in the field using isolated plants and simulated swards given 'hay' and 'grazing' management. Isolated plants of the hybrid grew faster than the parent species in midsummer, while meadow fescue grew fastest in autumn and ryegrass in early winter. Under competitive conditions and both management systems, the parent species maintained an equilibrium with each other but each was suppressed by the hybrid; this was probably because the hybrid grew faster in summer and the parent species did not do so in autumn and winter. It was concluded that the relatively small amount of fertilizer applied in autumn seriously decreased the ability of ryegrass and fescue to compete with the hybrid. Factors other than water and nutrients were involved in the ability of the hybrid to outgrow ryegrass in summer.-R.B.