IUFRO Breeding theory and progeny testing

Korea, a mountainous country with 64% of its land in forests, has a long history of close relationship with forests. Korean government and all people have made efforts toward reforestation, education and research. As a result, remarkable achievements have been made in Korea forestry, especially forest recovering. Tree improvement began early 20th century and breeding programs launched in 1956, starting with plus tree selection and seed orchard establishment.

Clonal seed orchard of Pinus densiflora in Korea

Seed orchards are the link between breeding programs and reforestation through the delivery of consistent, abundant yields of genetically improved seed. Thus, seed orchards are always involved in major breeding programs all over the world. Estimation of genetic gain and gene diversity of seed orchard crops is crucial for both theoretical study and practical management, which higher gain is the main target.

In Korea, all seed orchards are centrally owned, documented and managed by the Division of Tree Breeding in the Korea Forest Research Institute. Total area of seed orchard is 819 ha, and the conifer seed orchards produce genetically improved seeds, which is sufficient for reforestation. In parallel with establishing seed orchards, we also designate seed stands for the supplement of seed supply. We have designated 1,023ha from 11 species in Korea.

Gain could be obtained using orchard management alternatives (genetic thinning, selective harvest and both combined), while reasonable diversity was maintained. Clonal breeding value, fertility variation, pollen contamination and seed production are major factors in the considerations when genetic gain and diversity are estimated. Breeding values are estimated from progeny tests (OP & CP). Gene diversity is monitored by status number (Ns) and loss of diversity is relatively estimated compared to the reference population. By 50% genetic thinning (linear deployment), we expect 10-15% genetic gain in volume growth and some loss of gene diversity that is unavoidable but acceptable.

Genetic gain and seed production by genetic thinning (30% pollen contamination) in a clonal seed orchard of Pinus densiflora

For the trade or transfer of forest reproductive materials, adequate information about source and history should accompany the shipment. Following the OECD scheme for the Control of Forest Reproductive Materials, we have general rules and directions for official statement that a seed lot conforms to certain standards, which may include specific identity, origin, genetic characters and seed purity.

For the successful functioning of seed orchards, orchard managers, specialists and researchers should diligently observe, assiduously collect and consistently study all essential information on parental behavior, compatibility, combining ability and gene flow, and then translate this information into practical terms so that it may be employed in future seed orchards.