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Is linear deployment of clones optimal under different clonal outcrossing contributions in seed orchards

Prescher, F., Lindgren, D., El-Kassaby, Y. A.
Tree genetics & genomes 2006 v.2 no.1 pp. 25-29
Picea abies, breeding value, clones, genetic improvement, genotype, germ cells, outcrossing, seed orchards
Self-pollen seldom results in vital genotypes and can thus be regarded as unimportant. Large-sized clones (clones with many ramets) are more exposed to self-pollen and spread more self-pollen and thus contribute relatively less than small-sized clones. The size of clones required to maximize genetic gain at given diversity, considering that only outcrossing contributes to successful gametes, was derived for tested clones intended to establish a Norway spruce (Picea abies) seed orchard. The derived optimal deployment was compared with linear deployment according to Lindgren and Matheson (Silvae Genet 35:173-177, 1986), where the size of a clone is deployed proportional to its breeding value. The study covered a range of effective numbers between 5 and 50. The results suggest that linear deployment is a good approximation to optimal deployment when only outcrossing is considered. The difference between the two strategies is decreased by increasing clone number and is negligible except at low effective numbers.