Abstract:

Saplings of Eucalyptus grandis × E.urophylla regenerated by different vegetative propagation methods and generations were used as materials. Dynamics of four kinds of the endogenous hormones (abscisic acid, ABA; gibberellin, GA-3; indole acetic acid, IAA and zeatin riboside, ZR) in the leaves were detected using enzymelinked immunosorbent assays (ELISA). Regression analysis of the data was conducted with the growth characters to investigate the mechanism of eucalyptus senescence in the propagation processes. Results indicated that the contents of hormones in IAA, GA-3, ZR, and ABA/GA-3 value (k), ABA/ZR value and ZR/GA-3 value were all significantly different among the saplings. The six physiological indices could stably and accurately reflect the antisenescence capacity of eucalyptus, and predict the growth performance of the saplings. The IAA, GA-3 and ZR contents were all positively correlated with the antisenescence capacity. The higher the contents, the stronger the antisenescence capacity was and the faster the saplings grew. To the contrast, the k , ABA/ZR and ZR/GA-3 were negatively correlated with the growth characters. The growth characters were principal parameters and the hormone indexes were supportive parameters in determining the anti senescence capacity. The growth characters, integrated with the hormone indexes, could predict the growth and senescence progress in vegetative propagation process of E. grandis× E.urophylla. Based on the above testing parameters, the first generation of tissue culture was the strongest in the anti senescence capacity, the eighth generation of tissue culture was second, and the third generation from cutting was the weakest.

Key words: Eucalyptus grandis×E.urophylla, vegetative propagation, endogenous hormone