Abstract
According the observations, during a few years, on the frost damage of Cryptomeria growing in southern Hokkaido, it seems there are some relations between the tree-types and its frost-hardiness.
To obtain more informations and establish a method of selecting the hardier trees, Cryptomeria trees were classified into 3 types, (Fig. 1) and the frost-hardiness of each type was studied.
(1) At the afforested area, it is found that type I and II suffered less from frost damage than type III. (Table I and Fig. 2)
(2) Twigs, detached from trees of each type in midwinter, were frozen at -20°C for 20hrs. to determin the order of frost-hardiness. The results of the test shows that type I and II are hardier than type III. (Fig. 4, 5)
(3) In addition, the seasonal variations of frost-hardiness and osmotic concentrations, from November to May, point out that type I is hardier than type III. (Fig. 4, 5)
From these results, it is cleared that tree type has relation to the frost hardiness. Therefore, it is suggested that frost-hardy trees may be selected by tree type.
