SYSTEMS RYEGRASS VARIETIES
Colin Eady and Graham Kerr – the continuum from annual to perennial means ryegrass has something for everyone.
Twelve years of torture Words by: Anne Lee
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lant breeding has given farmers a range of ryegrass cultivars to suit just about any situation but it’s important they understand that if they’re heavily focused on one aspect there may be compromises on others. If yield and cool season growth are the top priorities then there are cultivars that can give outstanding results but it may be that same pasture will need renewal in less than five years. Barenbrug science officer Dr Colin Eady describes it as a push and pull kind of paradigm when it comes to breeding some characteristics. Lowering the amount of crude protein is another good example. Much of the plant’s protein is in the enzyme RuBisCO which incorporates CO₂ into the plant and is integral to the function of photosynthesis. “There might be excess protein in the ryegrass for the animal eating it but if we try and lower it to solve a nitrogen excretion issue, we’re going to compromise the very photosynthetic machinery that’s going to capture the carbon and build the sugars the plant needs to grow and achieve plant yield.
“That’s the push and pull we see so often and what breeders are working with all the time. “Most farmers would say the ideal ryegrass would be one that’s very high yielding, maintains quality and is very persistent. “But persistence and yield are inherently pulling in opposite directions. “To be more persistent the plant is putting more of it’s resources into being robust rather than growing an abundance of soft, tender leaves.”
is programmed to come back year after year and will sacrifice some of this year’s activities to have the reserves for next year,” he says. “What we’ve done in plant breeding is to create a continuum between the two extremes. “So, we have hybrids – the cross between the perennial Lolium perenne and the short-term Lolium multiflorum, also known as the Italian. “That also gives us a shot of hybrid vigour.
‘Most farmers would say the ideal ryegrass would be one that’s very high yielding, maintains quality and is very persistent.’ Barenbrug marketing manager Graham Kerr says the true perennial characteristics of ryegrass are what drive it to be hardy while annual varieties are “the party animals” here to grow as fast and as vigorously as they can. “Annuals aren’t programmed to put energy into reserves, they put it all into immediate regrowth whereas the perennial
Dairy Exporter | www.nzfarmlife.co.nz | December 2021
“Then we have the crosses back from the hybrids to either the perennial or annual to give intermediates. “That’s creating this continuum in growth and persistence,” Graham says. Warmer temperatures and farmers moving calving dates earlier over the past 20 years has pushed up late-winter/spring feed demand so cultivars with strong cool 39
