Dry matter yield, herbage quality and persistency of equivalent populations of perennial ryegrass with and without reduced flowering

Reducing the number of flowering tillers that perennial ryegrass produces would improve the feeding value of herbage and could also be used to reduce pollen flow to wild ryegrass populations. Equivalent populations with and without one or more genes that reduce flowering (normal and leafy populations, respectively) were compared over three harvest years (1999-2001) in a field plot experiment with two cutting managements (silage and simulated grazing). In 1999, samples of dried herbage from each harvest were analysed for leaf lamina content, in vitro digestibility (DMD), crude protein (CP) and water-soluble carbohydrate (WSC). The leafy population produced one-fifth to one-third as many reproductive tillers in May as did the normal population, depending on the management. Mean leaf content of the herbage over all harvests and managements was 63 g/kg higher in the leafy population but its mean DMD was only 7 g/kg higher. In August, September and October, when the leaf contents of the two populations were very similar, the mean DMD of the leafy population was 7 g/kg lower than that of the normal population. Mean annual dry matter yield over both managements of the leafy population was 6-8% lower than that of the normal population but the leafy population was slightly more persistent.