Winter hardiness in marginal populations of timothy

Summary A comprehensive collection of local fodder grass populations was carried out in the northern regions of Norway in 1972 and 1973. The main purpose was to find ecotypes with extreme winter hardiness. This paper gives results from experiments carried out with some of the timothy populations collected.After testing in dense stand a few of the most promising populations were selected for investigation of genetic variation within populations by growing in duplicate blocs of 100 clones from randomly selected plants. Twenty-two clones were selected from each of six populations and planted in separate isolated polycross fields. During 1986 to 1990 the half-sib families from these polycrosses were grown in two series of experiments laid out at two locations, Tromsø and Alta.Significant genetic variations were found for winter hardiness within all six populations tested, as well as interaction between families and locations, while the interaction effects between families and years were small and insignificant in all cases.Winter hardiness was strongly genotypically correlated in the positive direction with visually estimated general performance, but not correlated with digestibility.