Abstract:

The Eucalyptus grandis×E.urophylla cuttings from different ages of stock trees were taken as the experiment materials. The physiological and biochemical index of the cutting leaves, such as their photosynthesis, nitrogen metabolism, endogenous protected enzyme system, membrane lipid reaction, etc. were tested to explore the rules on Eucalyptus grandis×E.urophylla senescence with different age of scion mother tree. The results showed the indices had obvious different on chlorophyll content, soluble content, SOD activity, POD activity, CAT activity, MAD content and PRO content of different age of scion mother tree. The physiological index of the cuttings leaves measured accurately, controlled conveniently scion mother tree ages, and ensured the quality of the cuttings. The age of scion mother trees and the leaves of cuttings on senescence physiology had a clear link, chlorophyll content, soluble protein content, POD activity, SOD activity and PRO content and scion mother tree ages had negative correlation. The CAT activity and scion mother tree ages had negative correlation. Through measured the above physiological and biochemical indicators could determine the scion mother tree ages, the physiological indices of the cuttings' leaves were small, the ages of the scion mother trees were greater, the growth of the cuttings recessed quickly. MDA and the ages of scion mother trees were a positive correlation, the age of the scion mother tree could be determined by the amount of MAD, the greater the MAD, scion mother tree ages showed greater, and the growth of the cuttings recessed quickly. And CAT activity and the age of scion mother tree had no regularly , CAT activity should not be used to determine scion mother tree ages. So according to above testing results, it could be indicate synthetically that among the 3 young forests, the resistance to senescence of the one-year-old was the strongest, the two-year-old was stronger, and the three-year-old from cutting was the weakest. The change of physiological index was often affected by environmental conditions, Therefore, It should be under the same environmental conditions to judge the declines of cuttings' descendant, when the age of the ortet were determined, physiological index was first, the growth and morphology index must be considered, at the same time,they could be used to judge the senescence speed in cuttage propagation process of Eucalyptus grandis×E.urophylla.

Key words: Eucalyptus grandis×, E.urophylla, cutting propagation, scion mother tree, age effect, oxidize-resistant physiology