Breeding values of tree seed
The development of tree breeding values and a system of rating tree seedlots is based on a seedlot’s genetic worth for the trait of interest.
Genetic worth is an index that has been developed in British Columbia to assist seed orchard managers with optimizing the potential genetic gain from orchard seed. It is also used to translate changes in the level of genetic improvement in reforestation stock into growth and yield predictions.
Generally, breeding values are predicted for an average site in the seed planning zone. Tree breeding programs are moving into advanced generation selection (forward selection), and many programs incorporate traits with both quantitative and threshold or binomial distributions, such as pest or disease resistance. Consequently, government researchers use data analysis software to analyze complex linear mixed models.
Researchers are developing analytical methods to deal with both backward selection breeding values, based on parental breeding value prediction, and forward selection breeding values, based on within-family or animal model predictions. The methods use best linear prediction or best linear unbiased prediction methodologies.
- White, T.L. and G.R. Hodge. 1989. Predicting breeding values with applications in forest tree improvement. Kluwer Academic Publ., Boston, Mass. 367 pp.
- Stoehr, M., J. Webber, and J. Woods. 2004. Protocol for rating seed orchard seedlots in British Columbia: quantifying genetic gain and diversity. Forestry 77(4):297-303.
- Xie, C.-Y. and Yanchuk, A.D. 2003. Breeding values of parental trees, Genetic worth of seed orchard seedlots, and yields of improved stocks in British Columbia. WJAF 18(2) 1-13.