Genotype and location effects on internode length of Pinus radiata in New Zealand

Internode length of Pinus radiata D. Don in New Zealand is under strong additive genetic control, and it is an important index of the amount of clearwood yielded by unpruned trees. Variation between genotype in internode length is much greater on fertile, high-latitude sites, but rankings of genotypes are quite stable over all sites. Both multinodal (short-internode) and long-internode breeds have been developed to supply timber products for differing end-uses. Much greater yields of clearwood can be obtained from a long-internode breed, but this will be at some cost in gains for growth and form traits when compared to the most advanced multinodal tree type. It is important to match the choice of breed with the planting site, and with subsequent management of the forest crop; this will be greatly assisted when the effects of the tree breeding programme can be accounted for in existing forest planning models