Pasture plant breeding in New Zealand: where to from here?

Abstract

<jats:p>Ecologically sustainable pastures remain the base of New Zealand's competitive advantage in livestock production, but while modest but steady productivity gains from pasture plant breeding have been documented, these appear to be difficult to convert to livestock production, and pasture production is perceived as up against a ceiling. This paper discusses the contribution of pasture plant breeding, focusing on the ryegrasses, and to a lesser extent on white clover. Heritable variation is evident in the basic components of herbage growth and herbage quality. However, changes to individual traits are not reflected in improved integrated field performance. More precise information is required on how factors interact. New breeding technologies will allow integrated improvement of interacting factors. Evaluation trials and modelling should be managed to provide feed-back identifying the specific requirements of future high-performing systems. Keywords: New Zealand, plant breeding, ryegrass, white clover</jats:p>

Changes in plant morphological expression in 12 perennial ryegrass cultivars following frequent and infrequent cutting management

“…Furthermore, to summarize the responses across all the characters, there was good evidence that directional plant selection did occur in the aged swards as ten of the 12 seed accessions differed from their FC accessions and eight differed from their IC accessions. These differences involved a shift in the mean population value of individual characters with ageing and provide evidence to support the hypothesis of Easton et al (2011) for selective fitness pressures within swards.…”

“…Although Easton et al . (2011) recognized the potential for natural selection to shift the mean characteristics within a perennial ryegrass cultivar population, they found little evidence of this effect. Nonetheless, the possibility remains, at least in theory, for selection to occur within a single cultivar of a perennial ryegrass.…”

Multi-Trait Genomic Prediction Improves Predictive Ability for Dry Matter Yield and Water-Soluble Carbohydrates in Perennial Ryegrass

“…Perennial ryegrass is one of the most valued forage species in temperate regions of the world, characterized by relatively high nutritional value, and optimum seasonal and annual dry matter yield (DMY) from herbage, providing a cost effective source of nutrition, for ruminant livestock (Wilkins and Humphreys, 2003;Baert and Muylle, 2016). The historic rate of genetic improvement for seasonal and annual DMY and nutritive quality traits is moderate, between 4% and 7% per decade (Easton et al, 2002;Wilkins and Humphreys, 2003;Sampoux et al, 2011). One reason for the moderate rate genetic improvement is the complex nature of these traits, which makes it challenging to accurately measure.…”

Predictive ability of genomic selection models in a multi-population perennial ryegrass training set using genotyping-by-sequencing

“…Increased seasonal and annual level of herbage dry matter yield (DMY), a driver of livestock productivity, is a principal breeding objective for this species (Wilkins and Humphreys 2003 ; Williams et al 2007 ; Chapman et al 2017 ). However, the realised rate of DMY genetic gain has been modest, at between 3 and 4% per decade (Easton et al 2002 ; Sampoux et al 2010 ; Van Wijk and Reheul 1990 ). One underlying factor is that DMY is often not directly selected for in breeding programmes (Casler and Brummer 2008 ).…”