A breeding strategy for the New Zealand Radiata Pine Breeding Cooperative

This paper documents the breeding strategy of the New Zealand Radiata Pine Breeding Go-operative (NZRPBC) following a revision in 1997 to 1999. This co-operative serves 15 members in New Zealand and south-eastern Australia, and provides improved genetic material used for planting throughout New Zealand and in parts of Australia. In the revised strategy, emphasis on recurrent selection for general combining ability (GCA), a 2-superline structure, main population and breeds are maintained. A non- regionalised breeding programme, and a final selection around age eight years are also maintained. A new Structural Timber breed is to be formed, along with a Clear Cuttings breed (with modified emphases compared to the long- standing Long Internode breed). The Growth and Form breed will be expanded, recombining new superior parent clones. The existing Dothistroma-resistant breed will also be progressed, while the existing Long Internode and High Wood Density breeds will be used as sources of selections. Good parents not selected for the breeds will be used in the main population. A Guadalupe breeding population is also to be established. The combined populations are to have a census number near 550 and a target status number of 400. The role of the breeds is to get optimum genetic gain while delaying the build-up of inbreeding, and to be the main source of new selections for seed orchards. The main population will serve as a reservoir of genetic diversity, as a source of candidates for existing and future breeds, and as a form of 'genetic insurance'. Candidates within breeds will be crossed in disconnected factorials and tested as seedlings or as clones within families. Candidates within the main and Guadalupe populationwill be tested as seedlings. The previous full review of the New Zealand breeding strategy for radiata pine was in 1986. The strategy was revised because of subsequent developments that impacted on breeding, including: new information and new tested parents; adopting a collaborative government-industry approach to breeding; advances in breeding strategy, forest genetics and propagation techniques; and changes in emphases and practices in the forestry sector. The 1986 strategy had several key results, namely an emphasis on recurrent selection for general combining ability, a 2-superline breeding population with relatedness kept within superlines, stratifying the bleeding population to an unspecialised main population and specialised breeds (with some overlap), a single breeding programme for all New Zealand, and separate crossing for recombination and for estimation of GCA.