Abstract
The author collected seed from trees in stands of Cryptomeria japonica D. DON at eight sites. The sites, though within a relatively small areas, are greatly different in environmental conditions. The cold-resistance of each population was then compared in the field. The author found that there was a great difference depending upon seed source in the rate of survival of the seedlings after they passed one winter in the field. However, the author could not observe a correlation between the survival of offsprings and the environmental conditions in which the mother tree grew. This seems to be due to the fact that, since seed collection stands of Cryptomeria japonica are mostly man-made forests and have not been naturally selected, so that the gene-component of the seed collection stands has not reached equilibrium with the local environment.
There was a great difference in the rate of survival depending upon the way of planting. In each offspring group, the author tried three types of planting; (1) ordinary seedling planting, (2) bunch planting of two seedlings in one planting hole, and (3) bunch planting of one Cryptomeria seedling with one Abies veitchii seedling. The rate of survival of (3) was the highest. No interaction between seed source and the way of planting could be observed. Therefore, it is considered that both factors operate independently.
