日本産２葉松の産地試験

The seeds of Japanese two-leaf pine were collected from 30 stands in various places of Japan. (Pinus densiflora 14, P. Thunbergii 13, hybrid between both species 3). The size of seeds, and the growth and the drought resistance of seedlings from these seeds were examined and previously reported. Interspecific and intraspecific differences proved to be significant, but the cause of between-provenance differences was not ascertained.
In Dec. 1954, the 1-1/2 seedlings of these pines were planted in the Exp. Forest of Shimane Agr. Coll. on the slope of Mt. Sambe. Each plot (provenance) consisted of 14-18 seedlings without replica,. In 1962-64, tree height, breast height,diameter, number of cone bearing trees and cone number of each, tree were examined. (Table 2 ) The results are as follows.
1. Between-provenance differences significant were proved for height and diameter growth, total volume and percent of cone bearing tree in each plot, but the cause of differences could not be explained in relation to the environmental condition of the seed provenance.
2. Comparing the total growth in 1964 for each species group in disregard of provelance, hybrid group showed the largest in height, diameter and volume. In height P. Thunbergii group was the second, but in diameter P. densiflora group was the second. P. Thunbergii group beared the most cones, the next was P. densiflora group.
3. The winter 1962-63 had the heaviest snowfall and the lowest temperature for several decades. Durihg 1959-64, height growth of P. densiflora group showed the remarkable decrease in 1963, whereas the decrease of height growth of P. Thunbergii group was seen in 1964. The cause of this result could not clarified.
4. Considering from the mortality of seedlings in outplanting and the growth for ten years in this experimental plantation, it seems that P. Thubergii have an advantage over P. densiflora for the planting tree in this district.