Comparisons of Genetic Variation and Gains of 6-year-old Families from First-and Second-Generation Seed Orchards of Pinus massoniana

【Objective】 To evaluate genetic gain and effect of improvement of the first-and the second-generation clonal seed orchards of Pinus massoniana, and to provide guidance for the breeding, production and application of the genetically improved P. massoniana.【Method】Two 6-year-old progeny trials of open-pollinated families of P. massoniana using materials respectively from the first-generation and the second-generation seed orchards in Zhejiang Chun'an and Fujian Shaowu were measured for evaluation of growth performance, analysis of genetic variation and gains, and estimation of breeding values of the families. 【Result】There are large differences between progenies from different generations of seed orchard, while major growth traits including tree height, DBH, and volume all were higher than those of the control(i.e. the bulk selection from superior natural stands). The average individual volume and breeding value of the progenies from the first-generation seed orchard were 55.78%-84.62% and 40.66%-71.39% higher