Studies On Selection Of Drought-tolerance And Cold-tolerance And Cloning Of Low-temperature-induced CDNA In Acacia

As an excellent short-rotation species for industrial utilization, Acacia, with about 1200 species, characterized by fast growing, low soil fertility tolerance, nitrogen fixation, and soil amelioration, distributes widely along the world. Starting in 1950, the trials of introducing Acacia at a large scale were initiated in our country, and Acacia plantations have been developed quickly since then. From early trials to currently large scale establishment of acacia plantations, Acacia has played a crucial role in forest productivity increment and landscape restoration in southern China. There are continuous efforts to study characteristics of tree resistance. As for Acacia, the study on resistance for improvement of stand productivity tends to be essential and important after the completion of introduction trials and large scale establishment of commercial plantations.In this dissertation, the physiological mechanisms of the drought resistance of three Acacia species: A.mangium, A.auriculiformis and A. crassicarpa by controlling moisture and temperature in a growth chamber were investigated. The system of evaluating drought resistance was developed and applied for the selection of the three Acacia species. The provenances or families with a better drought or cold resistance were selected based on the assessment from the system. It provides a good methodology for selection of Acacia species with superior characteristics of resistance. The index system of the drought resistance for Acacia was also established and the mechanism of their cold resistance was explored when they were treated at low temperature. Moreover, cDNA subtracted library was constructed, and the simply molecular mechanism was discussed. With the aid of regional test of those materials, it was anticipated that the Acacia species with the characteristics of drought resistance, cold resistance, fast...