Danusevicius D, Lindgren D
Efficiency of selection based on phenotype, clone and progeny testing in long-term breeding
Silvae Genetica: 2002 51:19-26
The overall goal for long-term breeding was formulated as maximising annual progress in group merit (GMG/Y) at a given annual budget. Group merit is a weighted average of breeding value and gene diversity. Breeding strategies based on testing of phenotypes, clones or progeny for selection of parents for next breeding cycle were optimised as regards testing time and test entry size. The dependence of GMG/Y on genetic parameters, cost and time components was investigated. Numeric values were chosen with long-term breeding of Norway spruce in mind. The highest GMG/Y under the most likely parameter values for clone, phenotype and progeny strategies was 0.250%, 0.152% and 0.139%, respectively. The clone strategy was the best over the whole range of considered cases, except for the scenario with high narrow-sense heritability, for which the phenotype strategy was the most efficient. Except for low narrow-sense heritability, the phenotype strategy was the second best, but superiority of the phenotype strategy over progeny strategy was usually small. If reproductive maturity of the test parents could be shortened to below about 12 years, the progeny strategy may be better than the phenotype strategy. Comparably high costs (per parent) seem to be acceptable for promoting early sexual maturity. Narrow-sense heritability, additive variance at mature age, rotation age, plant-dependent cost and the time needed to produce the test plants had the strongest effect on GMG/Y. The clone strategy became less superior at high dominance variance. Short rotation age favoured the clone and phenotype strategies. Reduction of cost per test plant was especially beneficial for the clonal and progeny strategies.
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