WINTER HARDINESS IN MARGINAL POPULATIONS OF TIMOTHY

A comprehensive collection of local fodder grass populations was carri ed out in the northern regions of Norway in 1972 and 1973. The main pu rpose was to find ecotypes with extreme winter hardiness. This paper g ives results from experiments carried out with some of the timothy pop ulations collected. After testing in dense stand a few of the most pro mising populations were selected for investigation of genetic variatio n 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. Du ring 1986 to 1990 the half-sib families from these polycrosses were gr own in two series of experiments laid out at two locations, Tromso and Alta. Significant genetic variations were found for winter hardiness within all six populations tested, as well as interaction between fami lies 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 visu ally estimated general performance, but not correlated with digestibil ity.