Genetic variation and predicted gain from selection for winterhardiness and turf quality in a perennial ryegrass topcross population

Improved winterhardiness in turf-type perennial ryegrass (Lolium perenne L.) could expand its area of adaptation for turf and seed production, but breeding efforts have been hindered in part by a lack of identifiable winter-hardy germplasm. This research was conducted to estimate genetic variation for winterhardiness in a perennial ryegrass topcross population and to determine the feasibility of simultaneously improving turf quality and winter field survival. 'NK-200', a perennial ryegrass cultivar with acceptable winterhardiness in northern Minnesota, was topcrossed to a large sample of improved turf-type cultivars and 243 of the resulting half-sib families were selected for evaluation. Genetic variances, correlations, and predicted gain from single and multiple trait selection were estimated for winterhardiness and turf quality characteristics of half-sib progeny evaluated at two Minnesota locations in 1994 and 1995. Significant additive genetic variation and moderate narrow-sense heritability estimates were obtained for winterhardiness (σ(A)/² = 0.64 ± 0.11; h² = 0.59 ± 0.10). Fifty-five half-sib families had higher or equivalent winterhardiness than NK-200 suggesting transgressive segregation. Significant additive genetic variation was found for turf quality, crown rust (Puccinia coronata Corda) resistance, and leaf texture, but turf quality and leaf texture were undesirably correlated with winterhardiness (r(A) = -0.15 and -0.25, respectively). Gain from selection estimates revealed that single trait selection could rapidly improve winterhardiness and turf quality. However, some form of multiple trait selection would be necessary to improve winterhardiness and turf quality traits simultaneously. These results indicate that the potential exists to develop improved turf-type perennial ryegrass germplasm with increased winterhardiness.