Forward, backward selection and variation analysis of growth traits in half-sib Larix kaempferi families

Abstract Tree height and diameter at breast height of 30 half-sib Larix kaempferi families were analyzed at different ages. Analysis of variance revealed a significant difference in growth among different families. Phenotypic variation coefficients of the traits tree height and diameter at breast height among families of different ages ranged from 11.04 % to 31.74 % and 19.01 % to 19.83 %, respectively. Average heritability of tree height and diameter at breast height ranged from 0.87 to 0.96 and 0.93 to 0.96, respectively. Significant positive correlations were observed among all traits at different ages. By the method of multiple-traits comprehensive, six families (L18, L12, L8, L3, L25 and L20) were selected as being elite using a 20 % selection ratio at 12 years of age. Average values of these elite families were 11.15 % and 16.83 % higher than the total average for height and diameter at breast height, and genetic gains were 10.53 % and 15.79 %, respectively. Forty five elite individual plants were selected using a 5 % selection ratio which were 23.47 % and 24.90 % higher than the overall average for height and diameter at breast height, respectively.