Genetic gain in perennial ryegrass forage yield in Australia and New Zealand

Abstract

Genetic gain of forage yield in pasture species underpins long-term productivity improvements in pastoral agriculture. The value of proprietary seed sales in Australia and New Zealand has resulted in more public and private investment in perennial ryegrass breeding than other forage species, but this is still much less than for major row crops. Historic estimates of genetic gain in total annual dry matter (DM) yield for perennial ryegrass cultivars have ranged from 0.25 to 0.73% per year, but ongoing questions from farmers and industrygood organisations has prompted further assessment of recent genetic gains. Analysis of 46 Australian and New Zealand trials identified two distinct periods of genetic gain: (a) before 1990, where genetic gain for total annual DM yield was limited, and (b) after 1990 where consistent genetic gains of approximately 0.76% per year or 105 kg DM/ha/year have occurred, with rates higher than this especially in winter, summer and autumn. Investigations to better understand the key scientific and economic factors responsible for the observed changes in rates of genetic gain are warranted, as this may help inform policies and investment aimed at further increasing rates of genetic gain in all forage species. Keywords: germplasm origin, endophyte, Lolium perenne L., plant intellectual property rights, cultivar evaluation