Evaluation of semi-hybrid perennial ryegrass populations

Abstract

The yield potential of modern forage cultivars is a limit to production from pasture- based agriculture, and may influence profitability. Hybrid vigour has increased yield in a range of plant species, but is only partially captured in conventional forage breeding systems. The objective of this research was to assess the potential for harnessing hybrid vigour in a semi-hybrid breeding system for perennial ryegrass (Lolium perenne). Paired crosses among eight parental sources, including four cultivars and four ecotypes, were used to create 28 semi-hybrid populations. Parents, semi-hybrids and check cultivars were trialled in pure grass plots under rotational grazing for 2 years in the Manawatu. Dry matter yield data were used to estimate cumulative and seasonal patterns of hybrid vigour expression for cultivar x cultivar semi-hybrid combinations. The mean level of high parent heterosis was less than 2%. However, one combination exhibited significant (p