スギ肥培木の材質に関する研究 (第4報)スギ肥培木と対照木の年輪構成の差異について

This work is one of the studies made by the authors on wood properties of forest fertilized Sugi(Cryptomeria japonica D. Don). In this paper the widths of growth ring of fertilized trees and of non-fertilized ones are compared and examined under microscopic observation. These test trees are produced in the experimental forest of Kyoto University, Shirahama, Wakayama Prefecture(fertilized trees 3, non-fertilized trees 3, total number 6) and Okutsu-cho, Tomada, Okayama Prefecture(fertilized trees 2, non-fertilized trees 2, total number 4). The following items are observed and measured about the disk at breast height: a)Average width of annual ring b)Average number of cell consisting of an annual ring c)Width of late wood and number of cell d)Width of early wood and number of cell e)Width and number of false ring, number of cell. The results may be summerized as follows: 1)In diameter at breast height, height and volume, the differences between two populations characterized by fertilization and non-fertilization are quite significant at the 1 % level. (as shown table 1). 2)In the width of growth ring and average number of cell, the differences between two populations are significant at the 1 % level. 3)In the width of late wood and cell number, the differences are significant at the 5 % level except some portion, but are not significant at the 1 % level. The difference in the ratio of late wood between two populations is not quite significant at the 5 % level, so it seems reasonable to assume that the difference in the ratio of late wood between fertilized trees and non-fertilized ones is negligible. 4)In the width of early wood and number of cell, the significant difference between two populations is recognized at the 5 % level, but the difference in the size of cell is not significant. And this indicates that the difference in the width of growth ring between fertilized trees and non-fertilized ones depends upon the number of cell, but is not concerned with the size of cell. 5)The false rings are found more in fertilized trees, and the difference between two populations is significant at the 1 % level. 6)The significant difference is not recognized in the ratio of the number of cell in an annual ring to the number of cell in a late wood and false rings between two populations.