Impact of Clone Mixture Composition on Stability of 7th-year Mean Height in a Series of Norway Spruce Clone Tests

1990

S. 757-763

1 Abb., 5 Tab., 18 Lit. Ang.

Unselbständiges Werk

200088614

Canadian Journal of Forest Research 1990 ; 20(6), S. 757-763

Four mixtures of Norway spruce (Picea abies (L.) Karst.), each containing 56 clones, were analysed for height at age 7 years at six locations in southern Sweden. The number of clones in each mixture was subsequently reduced in a stepwise manner from 56 to 40, 30, 20, 10, and finally, 5 clones. The reduction process was conducted in three ways: (i) random deletion, (ii) deletion based on height growth, and (iii) deletion based on clone stability. No difference among the means of clone mixtures could be found for 20-56 clones for any elimination procedure tested, and no mixture x location interaction existed despite the number of clones in the mixture or the elimination process used. Location effects were consistently significant, independent of the number of clones in each mixture. Also, replication effects were significant, independent of the number of clones in each mixture. Also, replication effects were significant in all cases but one. Random elimination of clones resulted in weak differences between mixture means when 10 and 5 clones were included. Deletion of clones based on lack of stability or inferior height growth only slightly changed the variation pattern compared with when all 56 clones were present in each mixture. Relative height growth performance of clone mixtures with as few as 5 clones appeared to be stable within the region of Sweden that was represented by the trials.