Photoperiod and Temperature Effects on Root Cold Acclimation1

Abstract

Abstract Hardiness of intact roots of Potentilla fruiticosa L. cv. Katharine Dykes and Picea glauca Voss were determined during the autumn. Both extended photoperiod and warm temperature interfered with root acclimation to cold. Seasonally short days and near freezing temperature were necessary for maximum rates of cold acclimation of roots.