Efficiency of Selection Based on Phenotype, Clone and
Progeny Testing in Long-term Breeding
By Darius Danusevičius and Dag
Lindgren
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.