Abstract:

【Objective】This manuscript described the realized genetic gain and construction techniques of an open-pollinated seedling and seed orchard of Masson pine (Pinus massoniana). 【Method】The orchard was established in the 1990 to 1992 period and covers an area of 33.33 hm² in Baisha State-Owned Forest Farm, Shanghang County, Fujian Province, China. The orchard comprises more than 198 families of trees that were intensively selected from the excellent provenance area of Fujian Province. The orchard design was classified into two types: (1) Combined design of seed production area with progeny test area. (2) Separated design of seed production area and progeny test area. Based on the results of open-pollinated forests progeny test, trees with the lower breeding values were removed from the seed orchard (genetic thinning) on three occasions in 2000, 2004 and 2008, respectively. In 2003, a progeny test forest with seedlings from 68 half-sib families of the seedling seed orchard including a commercial check was established.【Result】A realistic genetic gain of 8.5% was obtained based on a test of 6-year offspring of Masson pine open-pollinated seedling seed orchard, and the volume growth of improved seed plantation was increased by 30% more than that of the unimproved stand. The results of simple sequence repeat (SSR) molecular analysis showed that the seedling seed orchards had high genetic diversity and random mating degree. The establishment of the first generation free-pollinated seed garden of Masson pine was successful. The following are the two key findings: (1) Quality and quantity of superior tree selection is the basis for achieving high genetic gain and continuing genetic improvement. (2) Scientific genetic evaluation of the progeny population and genetic thinning in the production population are the key techniques. (3) The detection, regulation and daily management of the mating system in a seed orchard are important conditions to ensure the normal operation of the orchand. 【Conclusion】 (1) For some fast-growing tree species such as eucalyptus and Masson pine, the seed orchard crops are not appropriate for pruning and dwarfing culture. It is more advantageous to adopt the technique of “Integrating the measured population and the producing population” to build the orchard. (2) Information regarding juvenile-adult correlation of the main traits of the established tree species is not yet available. It is necessary to carry out pruning and dwarfing culture. It is valuable to use the separated design of seed production area and progeny test area and to use the genetic evaluation data obtained from the separated progeny test to guide the genetic thinning of production population in the seed orchard production. In a word, the multi-generation seed orchard should be established in a location with good isolation conditions and relatively gentle terrain, and the orchard crops should be maintained without pruning and dwarfing to retain the natural tree shape. After completion of the production task in the seed orchards, the seed orchard trees could be transformed into forest tourism forest, forest health forest or timber reserve forest, to give full play to the multiple functions of the forest and reduce the operating cost of the forest improved seed base. This is a new model of multi-generation low-cost construction of seed orchards worth exploring.

Key words: Pinus massoniana, seedling seed orchard, realized genetic gain, genetic thinning, seed orchard crops pruning and dwarfing, improved seed base management mode