Survival, reproductive development and density of tillers in pure swards of Aries HD and Yatsyn 1 perennial ryegrass (Lolium perenne)

Abstract

Tiller number, survival and development were determined in clover-free swards of Aries HD and Yatsyn 1 high-endophyte perennial ryegrass established in the autumn of 1995 and continuously stocked with sheep. Few tillers died until mid December, after which survival approximated an exponential decay curve. There was no difference in the rate of tiller death between Aries HD and Yatsyn 1 swards. Seedheads were first observed on 19 November 1996 and were still visible on 26 March 1997. Aries HD appeared to have a greater proportion of initial reproductive tillers, but after mid-December a lower proportion than Yatsyn 1. There was an indication that Aries HD swards had a higher density of lighter tillers than Yatsyn 1. In a second experiment established in the autumn of 1997 rotationally grazed with sheep, Aries HD appeared to have a greater proportion of vegetative tillers during November and December, and greater mean ryegrass tiller density. Marginal differences in reproductive behaviour were not translated into any difference in in vitro organic matter digestibility between Aries HD and Yatsyn 1. Keywords: Aries HD, digestibility, flowering, perennial ryegrass (Lolium perenne), tiller demography, tiller population density, tiller survival, Yatsyn 1