Effects of key growth conditions on endogenous hormone content in tillering stem bases,germination of lateral buds,and biomass allocation in Indocalamus decorus

Physiological responses and changes in growth of Indocalamus decorus Q.H.Dai under different ecological conditions are essential for further understanding growth regulation and adaptive mechanisms and establishing an evidence-based management system for optimal growth. In this study, the endogenous hormone content in tillering stem bases, germination of lateral buds, and biomass allocation of this bamboo species in different growth environments were investigated. Among the endogenous hormones in the basal stems of tillers, indole-3-pyruvic acid and zeatin riboside were highly correlated with lateral buds that germinated to form shoots, while gibberellic acid was highly correlated with lateral buds that germinated to form rhizomes. The best lateral bud germination characteristics were achieved with full sun, a density of six plantlets per pot, and watering every 6 days. I. decorus plantlets used different resource allocation strategies depending on treatment. Different ecological factors influenced endogenous hormones in the bamboo stem base,which affected lateral bud germination and biomass allocation.

Laws of Trunk Extension and Branching Sprouted from Lateral Buds in Paulownia

Inorder to carry out trunk extension by lateral buds ,the laws of trunk extension and branching sprouted from lateral buds were investigated in 1-year-old seedlings of P.tomentosaxP,fortunei 33 under natural conditions.The results indicated：（1）Under conditions of high density and extensive management,42%of individuals in P.tomentosaxP.fortunei 33 showed pseudo dichotomous branching characteristics and could not extend their trunks in the second year.But other individuals showed the characteristics of sympodial branching and pseudo monopodial branching （not from terminal buds ）and could realize natural trunk extension.All the 3types of branching could be called branching of pseudo asis;（2）The stem form quotieties of extended trunk in all individuals wrer larger in the second year ,but only 14%of them could straight extend their trunks and 86%of them needed2-3years to reach straight trunk estension;（3）Among individuals which could extend their trunks ,from upper lateral buds to lower lateral buds on trunks ,the lengths and diameters of branches sprouted from lateral buds became smaller and smaller ,but the angles of branching up to trunk became larger and larger ,and the fourth pair of lateral branches reached to the largest,Under the fourth pair ,the angles of branches became smaller again and those branches all died.

Temperature Characteristics of Dormancy Development of Terminal and Lateral Buds in Paulownia

In order to probe the death reason of terminal buds and carry out trunk extension by using lateralbuds, the temperature characteristics of dormancy development of terminal and lateral buds in Paulowniatomentosa p. fortunei 33 were investigated by raising cutting branches on different date at 25 ℃ and 15 ℃.The results were as follows: ①The death reason of terminal buds and the first pair of lateral buds was itselfecological adapting strategy, not the injury of early frost and freezing; ②The lateral buds 2, 3 and 4 hadobtained the feature of winter dormancy, and could survive from cold winter, and widen its possible temperaturerange of sprouting to lower temperature by experiencing winter chilling; ③The lateral buds 2, 3 and 4 couldsprout at the same time in spring, but it was difficult to sprout for other lateral buds; ④The sprouting ofupper lateral buds could restrict the sprouting of lower lateral buds at 25 ℃, but not at 15 ℃.