| summary(En) : | End-grain heartwood wafers, 1 × 1 × 1/8" in size, were prepared from six tropical woods. Materials consisted of two groups of wafers; one was the extractive-free (F) which was subjected to successive extractions with ether, methanol, 0.01N NaOH and 0.01N HCl and the other was the unextracted original (A). Wafers of both groups were exposed to attack by Polyporus versicolor and Poria monticola for 90-days in a room maintained at 24°C. Two decay-test methods, the agar-glass rod-block method, in which a 3mm. diameter bent-glass rod was used as the bed of the wafer specimen, and the agar-feeder block-block method, in which the specimen rests on the feeder-block, were employed. In the decay test, six wood species, two fungal species, one test period, two treatment groups, two test methods and four replicates were used, iis, 6 × 2 × 1 × 2 × 2 × 4 = 192 specimens, each in its individual upright square bottle conta Thatning 25 cc. malt-agar on the bottom, were used.
The degree of decay was measured by weight loss, on the basis of moisture-free untreated wood weight before subjecting to decay. Weight-loss values for each specimen are shown in Table 1. The effects of main factors and their interactions are statistically studied in the form of the analysis of variance shown in Table 2.
The conclusion to be drawn is, that among the noticeable results, special emphasis should be laid on the interaction between the fungal species and the test method (M×F). The effect of this interaction is highly significant, although the effect of the test method (M) is not significant in the result of lying concealed behind the average of the two oppositeuresults. That is to say, each fungus has the optimum condition for its own activities; thus by differing the test method, significantly different weight Losses might be obtained with the same fungus. One should bear this point in mind in the laboratory decay tests and in the case of revising the standard method for the decay tests. |
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