The effects of plant density and frequency of cutting on the growth of cocksfoot (Dactylis glomerata L.). II. Yield in the vegetative and reproductive phases

Abstract

The effects of plant density and cutting frequency on the reproductive phase and yield in cocksfoot (Dactylis glomerata L.) were investigated. The plants of a clone were established at nine spacings that increased geometrically from 4 in. (10 cm) to 17 in. (42.5 cm) between plants to provide densities from 9 plants per sq ft to 0.5 plant per sq ft. They were cut every 2,4, or 8 weeks or cut once at the end of the growing season. Early in the season when growth was purely vegetative the highest yield per unit area was obtained with plants at high densities. Later, in some treatments, but while the plants were still vegetative, the combined effect of very frequent cutting and high density weakened the plants and the highest yields were then obtained at somewhat lower densities. When the plants first became reproductive, the highest yields per unit area were at low densities, as these plants were the earliest to become reproductive and their elongated tillers led to high yields. The optimal density for yield changed with time towards greater density as plants at these greater densities in turn became reproductive. Frequent cutting and high density reduced both the vegetative and reproductive fractions of the plant but the reduction was greater in the reproductive fraction. As high yields were associated with the reproductive fraction, the highest yields for the season were obtained from the uncut plants or from plants cut infrequently (8-week intervals).