Implications of species and management interactions for ranking perennial ryegrass (Lolium perenne L.) cultivars: a progress report from the two hemispheres

Experiments with a common design were established in County Cork, Ireland and in four dairying regions in New Zealand during 2012 to determine if forage value indices developed in both countries to rank perennial ryegrass cultivars should account for genotype x management interactions. Eight perennial ryegrass cultivars representing a range of phenotypes were sown in monocultures or in mixtures with white clover and received low or high rates of nitrogen fertiliser. Results from the first year of the Irish and Canterbury (NZ) experiments indicate no evidence that ryegrass cultivars re-ranked or that the scale of the difference between highest-yielding and lowest-yielding cultivars changed, when cultivars were sown in ryegrass-clover mixtures compared with ryegrass monocultures. All experiments will continue for three years to confirm whether or not these initial findings remain valid through different climate years and potential persistence differences among cultivars.