| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
The boron contents in the blackened Japanese persimmon (kurogaki) and heartwood of ebony (Diospyros ebenum), and further those in the leaves and stems of young persimmon trees, which were grown under the control of boron content in fertilizer, were investigated in the first year (2003) of this project. It was found that there is a significant difference of boron contents between normal portion of all persimmon samples (boron content<10 ppm) and blackened portions (several tens ppm). Also for ebony, a clear difference between heartwood and sapwood was observed, which suggests the participation of boron to the heartwood formation. In the fertilizing test, the young persimmon tree grew soundly under the boron concentration less than ten times of the standard (54 ppm), however above 100 times of the standard, the injury due to excessive fertilizing of boron appeared. The boron contents of the injured stems and leaves were same level of the blackened portion of persimmon xylem.
In the 2nd te
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rm of the project (2004), the relationships between boron content and heartwood formation, formation of abnormal tissue (i.e. black-heart in sugi (Cryptomeria japonica)), and adhesion tissue in aloes wood were investigated. For 13 species of Japanese and tropical hardwood and 2 species of softwood, significant difference in boron content was found between heartwood and sapwood. Exceptionally high boron content in the sapwood of inuenju (Maackia amurensis) suggested the contribution of wound by insect. The participation of boron to the black-heart of sugi was not found, because the boron content did not differ between normal heartwood and black-heart. Concerning the aloes wood, a part of sample showed high boron content suggesting the participation of boron to the formation of adhesion tissue for the recovery of injury.
From these results, the blackening found in Diospyros genus is a unique phenomenon, and the mechanism of the formation of blacken portion is interesting in connection with the preservation of wood. Less
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