While it doesn’t seem like an obvious one for the top 20 list of “essential survival items,” white clover-based pastures underpin most of New Zealand’s milk, meat and wool production in a quiet and unassuming way.   White clover currently contributes around $3 billion annually to the New Zealand economy and each one percent improvement in yield has been estimated to be worth more than $20 million.

White clover is integrated into pastures to improve nutritive value and animal intake rates, and to provide low-cost nitrogen for pasture growth.  It has also been a key in the development of New Zealand’s low-cost livestock farming systems.

Without white clover, livestock production in New Zealand would have to depend solely on fertiliser nitrogen.  This has obvious environmental consequences. 

Not only has New Zealand become very good at growing quality pasture with white clover as an integral component for its grazing animals, it also has a thriving export industry in producing clover seed, earning around $20 million a year.

Research has been fundamental in the success of this “white gold” in New Zealand, and AgResearch Grasslands scientists have earned an international reputation for their role in that research.  AgResearch is also leading the world in understanding the genetic composition of this essential pasture plant.

But there is still further research needed.

The challenge

New Zealand must continue to provide white clover innovations that maintain the competitive position of New Zealand’s pastoral industries.  Improvements are necessary for farmers to continue to achieve the four percent ongoing animal on-farm productivity targets.  But not only that, we have to look “outside the square” to see what other leading edge life science solutions white clover may provide. 

Researchers have a responsibility to keep pace with the rapid international developments in plant biotechnology, which is behind AgResearch’s plant breeding and genomics programme focus on new plants and plant gene technologies.  This focus will lead to improved germplasm development, and to genetic knowledge for forage plants and how they respond to environmental conditions.

AgResearch, based at Grasslands, has the world’s most comprehensive white clover research programme, aimed at developing plants that provide the meat and dairy industries with new market opportunities.

Current research programmes to improve white clover concentrate on further genetic improvements, forage quality and pest and disease resistance.

Underpinning this focus is AgResearch’s pioneering work in gene mapping.  A linkage map of the white clover genome is an essential resource for continued genetic improvement, providing considerable opportunities like locating genes controlling economically significant traits and for marker-assisted selection for delivery of superior white clover cultivars.  The current challenge for the genomic scientists who have produced this white clover gene map, is to utilise the wealth of information the map contains.

How leading edge science is meeting the challenge

Research is focusing on improving quality factors that affect animal and human health.  Combining extended flowering with higher condensed tannin levels in clover flowers may reduce the impact of bloat in the future. Other target traits include altering the balance between protein and metabolisable energy, increasing the omega-3 fatty acid content, and modifying traits associated with reduced methane emissions from sheep and cattle.

AgResearch has identified genetic resistance to two of New Zealand’s major clover problems – clover cyst and root knot nematode, and the breeding programmes are incorporating this resistance.  Other pest research is focusing on providing genetic tolerance to clover root weevil and clover flea.  Experimental clovers have also been developed to be effective against white clover mosaic virus and porina.

New Zealand-bred white clover cultivars are market leaders in every major international market, and this positions us strongly to capture future advances from genome mapping and functional genomics research.  Successful development of the world’s first comprehensive white clover genome map has opened the way for further gene discovery and clover improvement. 

Achievements

Improvements made by AgResearch to white clover over recent years have meant better yields, pest and disease resistance, drought and heat tolerance and improved animal performance.  Examples of this include USA grazing trials in which Durana, a new white clover released in Georgia, has provided an additional 100 kg/ha of beef in each year of a three year trial.  Crusader white clover has also topped independent trials in the UK for performance during the past two years.

Breaking the negative relationship between two important agronomic traits, leaf size and stolon density has been crucial to improving persistence of cultivars in all leaf size classes.

In fact, it would be fair to say white clover is getting better and better.

Commercial white clover cultivars produced alongside commercial partners, include Tribute which was launched this year at NZGA Conference.  Other leading white clover varieties bred by AgResearch include Crusader, Kopu II, Sustain, Prestige, Bounty and Durana.  Many of these new cultivars perform well in New Zealand but also perform strong internationally.  Crusader and Kopu II are good examples of this.

Contacts

For further information on white clover, please contact:
Dr Derek Woodfield, AgResearch Grasslands, phone 06-351-8073 Email derek.woodfield@agresearch.co.nz
Dr Bruce Campbell, AgResearch Grasslands, phone 06-351-8015 Email: bruce.campbell@agresearch.co.nz