Some considerations when selecting young jack pine families using growth and form traits
1992
Morris, D.M. | Parker, W.H. | Seabrook, R.
The purpose of this study was to provide background information on the heritabilities and genetic correlations for important growth and form traits in 3-year-old jack pine (Pinus banksiana Lamb.) to help evaluate an experimental five-category quality index. Height, diameter, crown diameter, number of branches, number of stem crooks, number of leaders, and crown density were recorded for 3-year-old progeny of 400 jack pine families at the Blue Bird Lake family test in northern Ontario. Narrow-sense (single-tree) heritabilities ranged from 0.08 for crown diameter to 0.17 for height, but no measurable component of family variance was associated with number of leaders. Genetic correlations were negligible between growth and some form characters, but were very high and unfavourable for number of crooks versus height and diameter (0.93 and 0.82, respectively). Thus, the preliminary indication is that selection for maximum increase in growth rate will result in a trade-off in terms of number of stem crooks. It was determined that the experimental quality index could not be used as a stand-alone selection tool. Discriminant analysis indicated that a high level of error (38%) in assigning progeny to the five quality classes existed. This error may be caused by overlap between quality classes, errors made in evaluation by field personnel, or most likely the inability to summarize overall tree form based on the five form traits determined for this study.
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