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

Abstract

<jats:p>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</jats:p>

Real-time, non-destructive and in-field foliage yield and growth rate measurement in perennial ryegrass (Lolium perenne L.)

“…For perennial ryegrass (PRG), estimated DMY gains of 4% to 5% per decade in the recent decades [12] and 0.75% per annum since 1990 [13] have been achieved. These lag behind the rate of gain in livestock and crops such as wheat and maize, where breeding for harvest index and plant density have led to substantial yield gains [14, 15].…”

Differences in nitrogen uptake and marginal yield response between low and high yielding perennial ryegrass (Lolium perenne) genotypes

“…Literature suggests the largest percentage genetic gains in perennial ryegrass have occurred in summer and autumn. Harmer et al (2016) reported 1.13 and 1.28 % per annum gain in these seasons, respectively. The impact of genetic gain in these seasons on the parameters of fitted response functions is discussed below.…”

“…Since the aforementioned research was completed, genetic gain in perennial ryegrass total annual forage yield in Australia and New Zealand has occurred at a rate of 0.76 % per annum (Harmer et al 2016), with greater rates of genetic gain in seasons of traditionally low forage growth such as winter, summer and autumn (1.01, 1.13 and 1.28 % per annum, respectively). As the majority of trials informing current recommendations were undertaken before the late 1990s, most data contributing to Australian and New Zealand industry best practice can only have been derived from European ecotypes naturalised to local environments, such as ecotype Victorian and the cultivars 'Grasslands Ruanui' and 'Grasslands Nui'.…”

Persistence of the yield advantage of perennial ryegrass cultivars: concept, evidence and implications

“…Pasture renewal is standard practice for maintaining the productivity of New Zealand's dairy, beef and sheep industries. It is also the mechanism by which superior forage cultivars are introduced and therefore through which gains in productivity traits achieved through plant breeding (Lee et al 2012;Harmer et al 2016) are captured. Pasture establishment is also costly, but it is generally assumed that the productivity benefits of new pastures substantially exceed the costs of establishment (Stewart et al 2014).…”