Study On Physiological And Biochemical Mechanism Of Age Effect And Position Effect In White Poplar

Vegetative propagation technique is applied widely in forestry production and it have wide development prospects, but clones were easily affected by the age of mother tree and the position scions and cuttings in ortet-maturation effect and position effect-appeared ageing phenomenon. In this research, morphological, growth, physiological and biochemical indexes about age and position effect were studied using ramet from different age and different position of triploid Chinese white poplar to find some markers that judge development stage of trees and to guide selecting suitable propagation material in production. The major results are described as follows:1. The morphological and growth indexes were significant differences among propagation material from different position of triploid Chinese white poplar ortet. The internode length, leaf aera, base diameter growth, height growth and petiole length decrease gradually with the height of propagation material increased in ortet. This differences mainly existed in ramets that from propagation material of root and crown position2. The photosynthetic physiological indexes and indexes about free radical have some differences between propagation material from different age and different position of triploid Chinese white poplar ortet, but this variation have no discernible regularity. So, it was hard to judge maturation effect and position effect of Chinese white poplar with photosynthetic physiological indexes and indexes about free radical3. The soluble proteins contents and fractions have some differences between propagation material from different age and position of triploid Chinese white poplar ortet and current-year branch in different position of trees, but this variation have not some regular rule in different positions, ages of trees and different tree species. So, it was hard to construct relationships between soluble proteins contents, proteins fractions and the different development phase of trees, therefore, it was not suitable as a marker in vegetative propagation4. The single plant hormone contents of IAA and ABA have not same rule neither in ramets from different position propagation materials of triploid Chinese white poplar ortet or in current-year branch at different position of trees. But the IAA/ABA has same rule: the rate of IAA/ABA in current-year branch at basal part of trees and ramets from root is higher than stem and crown propagation materials of triploid Chinese white poplar ortet. This showed that phase change of trees have relationships with contents variation of IAA and ABA. So, the relative differences of position effect of trees can be judged by comparing the IAA/ABA rate to reference materials that already juvenility or aged...