Improving white clover for Australasia

Abstract

Improving the genetic merit of temperate forage legumes helps ensure profitability and sustainability of our Australasian pastoral industries. Today’s plant breeders are supported by a range of underpinning research activities including genetic resources exploration and enhancement, plant physiology, plant health, feed quality, agronomy, quantitative genetics and plant biotechnology; and have collaborative interfaces with animal and farm systems science. Lifting the rate of gain by integration of molecular tools, innovative breeding strategies, and new genetic resources is the major objective of our white clover breeding network. This paper, presented at the Australasian Grassland Association’s recent Legume Symposium, focuses on the key research and development achievements in white clover breeding for Australasia, and on the success and future of an Australasian collaboration to breed improved cultivars for the region’s temperate environments. The paper reports on successful developments in the areas of improving white clover root systems for phosphate uptake, pest tolerance, development of novel inter-specific hybrids and marker-aided breeding. The successful trans-Tasman collaboration in white clover breeding and future work is also discussed.

Root morphology and architecture, and internal phosphate use efficiency, in related white clover cultivars of different ages

“…Reducing the cost to white clover of its herringbone root system by selection for high specific root length (Eissenstat 1992) is achievable (Crush et al 2008;) and could be augmented by selection for long root hairs (Caradus 1981). Marker-assisted selection shows considerable promise for clover breeding (Barrett et al 2006;Jahufer et al 2012) and would be particularly useful for root traits such as specific root length and root hair length.…”

“…White clover root systems vary, particularly in the ratio of taproot to fibrous root (Caradus 1977), and selection for long roots (Ennos 1985) and large taproot diameter (Caradus & Woodfield 1998) has conferred growth advantages under drought conditions. Heritability of several root traits in white clover is adequate to breed for elite root types (Woodfield & Caradus 1990) and, more recently, breeding populations have been screened for root traits (Jahufer et al 2012).…”

Rate of Genetic Gain for Persistence to Grazing and Dry Matter Yield in White Clover across 90 Years of Cultivar Development

“…In New Zealand alone, it is estimated that white clover adds approximately NZ$3 billion attributable to the seed industry, N fixation, and honey production . Globally, renewal of white clover is estimated at 3 to 4 million ha yr −1 (Mather et al, 1996).White clover breeding is important worldwide and is recognized as a priority in many countries with a pastoral-based livestock productivity system ( Jahufer et al, 2012). In terms of area, white clover is the predominant temperate forage legume serving as a companion to temperate grasses in grazing systems (Laidlaw and Teuber, 2001).…”

“…White clover in mixed sward pastures is estimated to occupy ?15 million ha in Australasia and 5 million ha in the United States. Globally, renewal of white clover is estimated at 3 to 4 million ha yr −1 (Mather et al, 1996).White clover breeding is important worldwide and is recognized as a priority in many countries with a pastoral-based livestock productivity system ( Jahufer et al, 2012). For example, the last checklist of white clover varieties (Caradus and Woodfield, 1997) described a total of 326 cultivars in relation to their maintainer institution, origin and breeding procedures used, agronomic performance, and disease susceptibility, among other characteristics, depending on the information available.…”

Prospects for improving perennial legume persistence in mixed grazed pastures of south-eastern Australia, with particular reference to white clover

“…and focused on white clover for high-rainfall and irrigated dairy pastures (Jahufer et al 2012). The other breeding program, conducted by NSW Department of Primary Industries based at Glen Innes, focused on white clover for beef and sheep dryland 5 pastures with an emphasis on improved persistence under conditions of summer moisture stress, heat stress and close grazing (Ayres et al 1996).…”