Genetic Variation and Selection of Growth and Morphological Traits in Filial Generation from Second Generation Clonal Pinus massoniana Seed Orchard

In 2013, seeds of 38 families of Pinus massoniana from second generation clonal seed orchard, of one common family and of second generation clone as CK1 and CK2 were collected in Chun’an, Zhejiang province. In 2014, seedling cultivation was carried out, and in March 2015, experimental forest of above-mentioned seedlings was planted. In November 2011, tally was made on the plantation. The result demonstrated that here were extremely significant differences among families in the growth traits (tree height, DBH and single plant volume) and morphological traits(crown width and trunk straightness) of different families. The phenotypic variation coefficient of volume and genetic variation coefficient were both the largest, indicating that the volume had variation potential at both genetic level and phenotypic level. The variation range of single plant heritability for growth trait was 0.15-0.62, and the variation range of family heritability was 0.52-0.82, indicating that the fine tree selection was mainly based on family selection combined with single plant selection within the family. Eight excellent families were selected according to the 20% selection rate, and the individual genetic gain of volume was 22.05%-36.60%, and the actual one was 28.60%-43.48%. The average genetic gain was 128.26%-152.25% higher than CK1 and 9.13%-19.33% higher than CK2. According to the 5% selection rate, 91 excellent individual plants of 26 families were selected. Compared with the average of the forest, the individual genetic gain of volume was 80.12%.