The Selection Of Superior Clones Of Taxodium Mucronatum Tenore

Taxodium mucronatum, one species of the genus Taxodium Rich in the family of Taxodiaceae, was widely planted in mountainous area and wetland on the purpose of both protection-forest and timber production forest. However, nothing has been reported yet on its breeding, propagation till now and selection of superior clones and scale seedling production of Taxodium mucronatum. Based on the research on the traits of growth, crown types, leaf color, a group of clones of Taxodium mucronatum for different breeding goals as fast growing, golden leaf and nice crown were selected. Besides this, the salt tolerance and photosynthesis characteristics of some clones were also evaluated. The final goal of this study is to select several superior clones of Taxodium mucronatum with virtues in fast-growing, nice crown, golden leaf and high salt-tolerance. The main results of this dissertation are as follows:100 kg seeds of Taxodium mucronatum were introduced from Eastern Mexico by Wujiang City nursery Co., Ltd in 2000, and a population of 100000 seedlings was established at Wujiang City nursery the next year. In 2003, 991 plus trees had been selected from it based on the individual investigation of growth and crown characteristics, among which, 837 plus trees were selected for their merit of fast growing, 92 trees for their unique crown, and 62 for their golden leaves. The selection differential (S) of diameter at base (D) and height (H) were 0.84cm and 56.78cm respectively, and the selection intensity (I) of D and H were 1.5 and 1.89 respectively. On the whole, a conclusion could be drawn that Taxodium mucronatum could be easily vegetative propogation due to their high survival percentage (86% for cuttings and 95% for transplants), whereas a significant variation of survival ratio among plus trees was found.897 clones originated from plus trees of Taxodium mucronatum were tested at Wujiang nursery in March, 2004. The ground diameter (D) and height (H) of each ramet were investigated in March, 2005. A significant variation of growth was found among...