| Genetic variation of tracheid length, specific gravity, latewood percentage, height growth, and ring width among and within four provenances of tamarack (Larix laricina (Du Roi) K. Koch) was investigated in a ten-year-old provenance test that was planted in Thunder Bay, Ontario. Significant genetic variation of tracheid length, height growth, and ring width was found among provenances and among clones within provenances. A south-north trend of decreasing provenance means with increasing latitude was found for tracheid length, height growth, and ring width. Fast-growing provenances generally had longer tracheids than slow-growing provenances. Variation of specific gravity and latewood percentage was not significant among provenances or among clones within provenances. Variance components and broad-sense heritabilities of wood properties due to clones within provenances were larger than those due to provenances. However, variance components and broad-sense heritabilities of growth characteristics due to clones within provenances were smaller than those due to provenances. Positive genetic correlations (r = 0.03 to 0.88) between wood properties and growth characteristics were detected, and the possibility of improvement of both wood properties and wood volume in tamarack was discussed. |
