Selection of superior trees of Betula alnoides

Key words: 
• forest tree breeding /
• Betula alnoides /
• selection of superior tree /
• selective index

Abstract: The quantitative properties , qualitative properties and environmental factors of 261 candidate Betula alnoides trees in 25 counties were measured .The correlation analysis of 9 properties of these candidate trees showed that volume and straightness of stem could be used as the main indexes for selection of superior trees of B . alnoides .The indexes of tree-selection were defined by quantity regression .The multiple entry quantity model was established for different locality factors , stand types and ages of tree with volume .Its multiple correlation coefficient was 0.920 815 .There was a difference between theoretical and realistic volume ;the frequency of difference was in normal distribtuion .The difference was the selection index Ii for superior trees selection and I 0.5 was the foundation of classification .The superior tree selection standards were as follows :(1)Class Ⅰ superior tree :Class Ⅰ straightness of stem , Ii 0.381 257 .(2)Class Ⅱ superior tree :Class Ⅰ orⅡ straightness of stem, -0.381 257 Ii 0.381 257 .(3)Class Ⅲ superior tree (normal tree):Ii -0.381 257 .The 46 class Ⅰsuperior trees and 145 class Ⅱ superior trees were selected by the standards .They accounted for 17.62 % and 55.56 % in all candidate superior trees respectively .[ Ch , 2 fig .2 tab .11 ref .]