Preliminary seedling selection of superior clones of pot culture Betula platyphylla

The goals of this study were to select superior clones of pot culture Betula platyphylla, and to achieve maximum genetic gains and economic benefits based on gene additive and non-additive effects. A total of 37 birch clones obtained through tissue culture techniques were used to study height, ground diameter, number of lateral branches, leaf area and internode length for two years and significance analysis of their difference. Finally, using the methods of membership function in fuzzy mathematics and principal component analysis, we provided weight value of each character and comprehensive evaluation of the clones. The results showed that there were significant differences (P < 0.01) in each of five traits (height, ground diameter, number of lateral branches, leaf area and internode length). The correlation analysis indicated that the height was positively correlated with the ground diameter, lateral branch number and internode length, but negatively correlated with the leaf area. According to the average of the two-years membership function value, the clones were classified into four grades: grade 1, grade 2, grade 3, grade 4. Seven clones were identified as grade 1, of which the height, ground diameter and number of lateral branches were 11.31%, 9.91% and 8.93% higher than average, respectively; while 13 clones were classified as grade 2, and these may be used as candidates to increase genetic diversity.