OPTIMAL UTILIZATION OF CLONES AND GENETIC THINNING OF SEED ORCHARDS

A mathematical method is developed for assigning clones utilization fa ctors (= relative numbers of copies) given an upper bound on the utili zation factor of each clone. The mean genetic value is maximized under a diversity constraint. The optimal utilization for a clone is linear ly related to the genetic value of the clone when this value is not to o low and the upper bound is inactive. It is argued that this method i s a useful tool for genetic thinning of seed orchards. The method is e xtended to the situation when the clones can be organized into groups of similar clones. For each group an optimal linear utilization can be found; in the simplest case the slopes are the same for all the group s. The method is applied to a Norway spruce seed orchard with 36 clone s for which predicted breeding values are available.