| Co-Investigator(Kenkyū-buntansha) |
SATO Keiichi Tokyo University of Agriculture and Technology, Faculty of Agriculture, Assistan, 農学部, 助手 (90178723)
SUGIYAMA Tamiji Tokyo University of Agriculture and Technology, Faculty of Agriculture, Lecturer, 農学部, 講師 (80015099)
KUBO Takafumi Tokyo University of Agriculture and Technology, Faculty of Agriculture, Associat, 農学部, 助教授 (00015091)
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| Budget Amount *help |
¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Research Abstract |
Specific gravity used as an important index of wood properties is closely related to the quantitative pattern of early- and latewood formation in stems of conifers. In this study, seasonal process of early- and latewood formation was observed using pin-marking or cutting methods, and some endogenous hormones such as indole-3-acetic acid (IAA), abscisic acid (ABA) and cytokinins (CKs), which included in cambial, phloem and differential zone, was qualitatively and quantitatively analyzed throughout a growing season.
1) The quantitative variation on latewood observed among trees or in stems of a tree indicated the relation to the rate of latewood cells production, and it was considered that the rate was influenced by activity of earlywood formation, namely the time of transition to latewood and the rate of earlywood cell production.
2) The transition to latewood was brought about by the considerable reduction of IAA levels, and it occurred when the levels decreased in region of 120-160ng/cm
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^2. Maximum peak of IAA concentration effected on the time of transition to latewood and the rate of earlywood cell production. In the stem just below crown base after pruned remarkably, IAA maintained higher level during relative long period, resulting in increase of production of latewood cells. As for ABA known as inhibiting substance for growth, the seasonal variation was little recognized within stems or in any trees, so that it was not found the relation to the wood formation.
3) In deciduous and evergreen trees, IAA was present more less in cambial zone of stems even during the dormancy, and it brought about the reactivation of cell division, before IAA was synthesized in new bud and leaves. But cambial and differential activity after initial stage may be influenced by current IAA.
4) Ribosilzeathin was found in cambial zone of stem, which was a kind of CKs known as promoting substance. However the relation to wood formation was not recognized, because seasonal variation on its concentration was obscure. Less
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