The examination of some winter hardiness components in grasses using canonical variate analysis

SummaryWinter vigour, winter burn, freezing damage and early spring yield were measured in 24 perennial ryegrass varieties which varied in their degree of winter adaptation. Winter vigour and winter burn were negatively correlated due to senescence in the dormant varieties. Cold resistance, measured in a freezing test, was also negatively correlated with winter burn but was independent of spring yield. Spring yield was positively related to winter vigour but negatively related to winter burn. The more dormant varieties which sustained most winter burn were better able to survive freezing.A canonical variate analysis showed that the first two canonical variates accounted for 87·8% of the total variation. Interpolation from the means of the four characters suggested that the first canonical variate represented adaptation to winter conditions. A generalized model based on these findings is proposed and its use in the formulation of grass breeding strategies discussed.