The study comprised 16 perennial ryegrass trials, each lasting three years, in Waikato, Taranaki, Manawatu, Canterbury and Southland and showed significant differences among perennial ryegrass cultivars in total annual and seasonal drymatter (DM) yield. All trials were grazed, run to New Zealand seed industry standards and audited by AsureQuality.
Authors Graham Kerr, David Chapman, Errol Thom, Cory Matthew, Aart van der Linden, David Baird, Evan Johnston and Jen Corkran, of Agriseeds, DairyNZ and Massey University, said the study reinforced gains made in pasture development, gave farmers confidence in cultivar selection and helped set better protocols for future trials.
Chapman, DairyNZ principal scientist feed and farm systems, said the study was unique because it included ryegrass cultivar and endophyte combinations that had not featured in other trials.
“The more data we have on cultivar performance in different regions and different years, the greater the reliability of information that we get on relative cultivar merits. More data equals more confidence.”
As well as recording annual and seasonal DM yield, researchers evaluated ryegrass cultivar persistence, plant pulling and crown rust. Variations in seasonal DM yields recorded during the study were significant enough to translate to marked differences in profitability, and showed how pasture development had advanced over the past decade.
“A good example is the extra winter growth that has been achieved in the move from NZ Mangere ecotype-based plant breeding material to Spanish material,” Kerr, technical development manager for Agriseeds, said.
“There was a difference of 300kg DM/ha recorded between the lowest and highest winter diploid yields, which translates to increased profitability of $120/ha, if an economic value of 40c/kg additional DM/ha is assumed. And that’s only for June and July. Over an entire 12-month period the total gain is much higher.”
Not every cultivar evaluated during the study was presented in the final data set, because only those that consistently demonstrated the best genetic gain were released commercially, Kerr said. There were 67 breeding lines from Agriseeds evaluated but 66 were omitted from the results reported. The one chosen is now known as Trojan.
“A one in 67 chance of release shows how rare such top performers are in plant breeding,” Kerr said.
Publishing the study was important because it also highlighted the need for better methods of measuring pasture persistence in seed industry testing protocols, he said.
“We need to test in real farm conditions and results of this study have helped the industry move to better trial protocols.”