Farm Table says:
Drought tolerant white clover cultivar for dry margins
What is the problem?
A breeding project was undertaken between April 2005 and June 2009 by the NSWDPI/AgResearch ‘White Clover Improvement Alliance’ to develop drought tolerant white clover cultivars for the low rainfall ‘dry margins’ of eastern Australia.
What did the research involve?
A breeding project using conventional breeding has developed white clover (Trifolium repens L.) cultivars for dry margins environments.
This is the third breeding cycle of the national program that has previously developed cultivars with tolerance of summer moisture-stress to provide reliably persistent cultivars for the existing white clover zone (850-1,000 mm AAR). This breeding cycle has developed three experimental varieties with local adaptation to low rainfall (700-850 mm AAR) conditions.
The breeding strategy comprised:
- selecting superior genotypes
- crossing elite germplasm and
- in situ progeny testing of breeding lines for the expression of key traits
The selection criteria were stolon survival through hot/dry summers (and strong autumn recovery), high herbage yield (including high warm-season growth and high winter activity) and reliable persistence for at least four years.
Parental selection was also applied for seed yield, uniformity of leaf size and flowering pattern, and freedom from disease and virus symptoms.
What were the key findings?
The project successfully completed the field evaluation of the 95 breeding lines and 5 cultivar checks and identified 3 outstanding synthetics that are superior in agronomic performance to both Haifa and the other white clover cultivars under test.
Results to the 4th growth cycle show that:
- Haifa performed poorly and Tribute was the best performing check cultivar
- three lines (39, 50, 70) performed substantially better than Tribute in yield and persistence
- a further 25 lines were identified as having outstanding persistence – these represent a pool of locally adapted germplasm for progressing to a future breeding cycle
A 10-year plan has been developed for the continuation of breeding, evaluation and commercialisation of a new generation of white clover cultivars for climate change. This will more fully exploit the potential of these derived breeding lines, and the established capability of the Alliance, to develop robust white clover cultivars with tolerance of ‘heat & dry’ for this new era.