New Zealand Journal of Forestry (1976) 21(2): 239–247
©New Zealand Institute of Forestry
Selection of Pinus radiata clones in New Zealand for planting from cuttings
M.D. Wilcox , I.J. Thulin and T.J. Vincent
Five hundred Pinus radiata trees were selected in 6- and 7-year-old stands at Kaingaroa Forest in 1966. The aim was to select the best tree in every 30 for combined superiority in stem straightness, branching habit, and vigour. Wood density was determined on each tree, and the 250 highest density ortets were selected for clonal testing.
Cuttings from the 250 ortets were set in the nursery in May 1966, and 206 clones rooted sufficiently well to be included in clonal field tests. An average of nine cuttings per clone were planted in a replicated test on a Tarawera Ash site in Kaingaroa Forest in June 1968.
Further cuttings, taken from the ramets in the clonal test, were set in the nursery in 1970 and 1971. Of the 206 clones, 56 failed to re-root better than 35% and were accordingly culled.
The cuttings in the Kaingaroa test were measured in 1972. A multiple trait selection index was used to rank the clones, and on the basis of this 40 of the remaining 150 clones were culled. The 110 clones left were planted in repropagation hedges in 1972 and the best 65 of them were selected for remeasurement in the Kaingaroa trial in 1974.
The 65 clones were re-ranked in 1974 using a new selection index incorporating stem volume, straightness, branching quality, and wood density. Regardless of how the economic weights "were varied in the index, two of the clones were always in the top rankings. Both clones are fast growing, have superb stem form, have high wood density, and root well from cuttings. Efforts are now being made to produce large numbers of cuttings of the top ten clones for demonstration plantings and to investigate whether their good growth rates can be maintained by hedging in clonal archives.