Studies on the regulating mechanisms of stem form and cambial activity in broad-leaved trees

点击翻译按钮获取中文摘要

1. The flooding treatment altered the growth, morhology, stem anatomy and ethylene production of Fraxinus mandshurica and Alnus japonica seedlings. Fooding stimulated diameter growth of the submerged stems by increasing both the number and size of wood fibers produced ; however, the thickness of the cell walls of the wood fibers was reduced by flooding. In response to the flooding treatment, the seedlings formed abundant adventitious roots which grew through the hyperhydric tissues. Aerencyma tissues were observed in the bark of the adventitious roots. Flooding also enhanced ethylene production in the submerged portions of stems.2. GA3 prevented the bending of branches in the weeping type of Japanese cherry, Prunus spachliana. Eccentric growth of GA3-treated branches was observed. In the xylem on the upper side of such branches the presence of gelatinous fibers, which stained strongly with fast green, was demonstrated.Moreover, a less dense distribution of vessels and a steeper angle o … More f cellulose microfibrils in the secondary walls of fiberes were also observed on this side. Similar features were noted in the xylem of the branches of cherry trees of the weeping type. These results suggest that GA3 induces tension wood on the upper side of branches of Prunus spachiana of the weeping type, so that the branches become to grow upwards, resembling branches of the upright type.3. The application of uniconazole-P,an inhibitor of GAs biosynthesis, to stem nodes of horizontally-positioned, 2-year-old Fraxinus mandshurica Rupr.var.japonica Maxim. Seedlings at various concentrations significantly inhibited not only righting the stems but also wood formation. The application of GAs (GA3 and GA4) in combination with uniconazole-P negated the inhibitory effect of the treatment of uniconazole-P alone. The GAs alone did not affect wood formation, however, both GAs increased wood formation on both the upper and lower sides of horizontal stems with an increase in the concentration of combined uniconazole-P.In all of the seedlings, tension wood was formed on the upper side of stems. The application of uniconazoleP alone at various concentrations did not inhibit the formation of tension wood fibers. Less