In the coming weeks, Richard Rennie will examine some of the work quietly taking place to help farmers deal with tougher climatic challenges. This week begins with work by AgResearch trialling more drought resistant clovers and grasses.
IT IS rare for plant scientists to claim they are excited by new varieties they are working on, preferring to hold back until the proof lies in the commercial pudding.
But there is a sense of excitement among AgResearch’s forage team about the unit’s latest clover hybrids, and what they could mean for the resilience of New Zealand farms under climate change.
Dr Jim Crush and his plant team at AgResearch Ruakura have been at the forefront of work to try and develop a future-proofed clover hybrid and grass types as climate change sinks its teeth into pastoral production.
“Certainly, improved moisture stress tolerance is a big driver for a few of our programmes as the climate has definitely got lumpier in the last few years,” Crush said.
His team is tasked with looking further ahead into commercialising varieties in a process that can take over 10 years from conception to farm paddock sowing.
Thanks to a relatively early start, farmers can expect to see the first commercially available results of the team’s white clover hybrid efforts in five years’ time.
Working with the PG+ Group, which comprises AgResearch, Barenbrug, PGG Wrightson Grasslands Innovation, B+LNZ and DairyNZ, the team has crossed conventional white clover T.repens with old world dryland clover T.occidentale.
The clover can be found above the high tide line in dry sandy parts of Brittany, Cornwall, Ireland and the Channel Islands.
Dryland field trials are now under way on Lincoln University’s Ashley Dene’s stony soils and on sandy country near Bulls.
As NZ’s go-to white clover, T.repens was introduced and thrived at a time when soil moisture was more reliable, and drought periods shorter or less frequent.
Despite its shortcomings in this tougher climate change world, Crush says the new hybrid retains 87% of T.repens’ genetic material. As a result, it does not suffer any loss of the characteristics like high-feed value that made white clover what it is.
“But it is the remaining 13% of wild genes that include traits for drought tolerance that we see making a difference,” he said.
Those traits include a thicker, longer tap root and thicker leaves capable of holding a greater amount of moisture.
T.repens’ genetic pool is relatively limited to clovers that tend to perform best in damper conditions. Crush believes the strategy of developing hybrid clovers is looking like it will be here for keeps.
“It just gives breeders greater genetic variability to play with,” he said.
He also sees it as a positive that the hybrid has been arrived at through conventional plant breeding, removing the tough issues of trialling and possibly perception that accompany any GE type crop.
While clover hybrids are looking promising in a push back against the climate change challenge, work is also under way on examining ryegrass options.
As a species, ryegrass growth is affected by air temperatures over 25C, where heat stress occurs and even if moisture levels are adequate, growth slows considerably.
Shallow root systems also challenge pasture over dry weather, and bring issues of persistence when also grazed repeatedly under such conditions.
Crush says while clover research is more advanced, some promising developments are appearing for grass alternatives too.
“We have developed a range of hybrid ryegrasses and cocksfoot grasses, some which are looking very interesting,” he said.
Hybrids of standard cocksfoot crossed with a Himalayan species “shouted hill country sheep and beef” to Crush and his associates.
Similarly, some early rye-fescue hybrids appear to offer the best of ryegrass quality with fescue’s drought tolerance.
He is anticipating a significant shift within the seed industry away from a “one size fits all” grass approach in coming years.
“As the climatic extremes have grown on a regional basis, I think we will shift to more regionally adapted hybrids,” Crush said.
“We are seeing that already to some extent with the Forage Value Index breaking NZ into four regional zones
Agresearch’s work on its controversial genetically modified High Metabolisable Energy (HME) grasses also continues to make steady progress.
The research body is coy about drawing attention to the grasses, but has reported they have performed well in controlled growing conditions in its United States trials.
Principal scientist Dr Greg Bryan reported that the grasses are now growing in field trials in competition with one another, as they would in a pasture situation. The grasses include high energy and drought tolerance among their traits.
However, their commercial release here remains dependent upon changes in this country’s regulations around genetically modified material.
