<abstract xmlns="http://www.w3.org/1999/xhtml"><p> Progeny-testing is a common element in tree breeding. It takes long time until trees reach the sexual maturity. That time could be used for field testing followed by progeny-test of the selected phenotypes (two-stage strategy), or the time until mating could be reduced by forcing early flowering (singlestage strategy). Benefit of phenotypic pre-selection followed by progeny testing in long-term breeding was assessed as a function of the age at the pre-selection by the aid of a deterministic tree breeding simulator. As a criterion of goodness of a breeding program, annual progress in group merit (GM/Y-refers to the rate of change in the average of genetic gain and gene diversity) at a total budget constraint was used. For simplicity, a long-term program with balanced selection was studied. Scenarios with different genetic parameters, cost and time components were evaluated and optimised for resource allocation. At the optimum age of mating for progeny test, two-stage Phenotype/ Progeny strategy generated higher GM/Y than singlestage Progeny strategy at the age of mating for progeny test equal to three years, except for a typical scenario with weak JM correlation, low heritability and long rotation time. High heritability, short rotation and strong J-M genetic correlation favoured phenotypic pre-selection. Optimum age for phenotypic pre-selection varied from 6 to 17 years and the percentage of GM/Y lost in comparison to the maximum due to delay of mating for the progeny test until age 15 and 25 years ranged from 0 to 14% and from 1 to 29%, respectively. In the case of low heritability, long rotation, low J-M correlation, high cost for cycling and low budget, early mating age would bring little benefit if compared to mating at the optimum age. We suggest that, in long-term breeding based on progeny testing, investment in phenotypic pre-selection is more beneficial than investment to achieve early flowering to initiate the progeny test early.</p></abstract>

Progeny-testing is a common element in tree breeding. It takes long time until trees reach the sexual maturity. That time could be used for field testing followed by progeny-test of the selected phenotypes (two-stage strategy), or the time until mating could be reduced by forcing early flowering (singlestage strategy). Benefit of phenotypic pre-selection followed by progeny testing in long-term breeding was assessed as a function of the age at the pre-selection by the aid of a deterministic tree breeding simulator. As a criterion of goodness of a breeding program, annual progress in group merit (GM/Y-refers to the rate of change in the average of genetic gain and gene diversity) at a total budget constraint was used. For simplicity, a long-term program with balanced selection was studied. Scenarios with different genetic parameters, cost and time components were evaluated and optimised for resource allocation. At the optimum age of mating for progeny test, two-stage Phenotype/ Progeny strategy generated higher GM/Y than singlestage Progeny strategy at the age of mating for progeny test equal to three years, except for a typical scenario with weak JM correlation, low heritability and long rotation time. High heritability, short rotation and strong J-M genetic correlation favoured phenotypic pre-selection. Optimum age for phenotypic pre-selection varied from 6 to 17 years and the percentage of GM/Y lost in comparison to the maximum due to delay of mating for the progeny test until age 15 and 25 years ranged from 0 to 14% and from 1 to 29%, respectively. In the case of low heritability, long rotation, low J-M correlation, high cost for cycling and low budget, early mating age would bring little benefit if compared to mating at the optimum age. We suggest that, in long-term breeding based on progeny testing, investment in phenotypic pre-selection is more beneficial than investment to achieve early flowering to initiate the progeny test early.

Progeny Testing Preceded by Phenotypic Pre-selection – Timing Considerations

Silvae Genetica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Progeny-testing is a common element in tree breeding. It takes long time until trees reach the sexual maturity. That time could be used for field testing...

Progeny Testing Preceded by Phenotypic Pre-selection – Timing Considerations

Published Online: Oct 27, 2017

Page range: 20 - 26

Received: Sep 15, 2003

DOI: https://doi.org/10.1515/sg-2004-0004

Keywords
annual gain, juvenile-mature correlation, gene diversity, group merit, optimisation, two-stage selection, stage-wise selection, flowering induction

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Progeny Testing Preceded by Phenotypic Pre-selection – Timing Considerations

Published Online: Oct 27, 2017

Page range: 20 - 26

Received: Sep 15, 2003

DOI: https://doi.org/10.1515/sg-2004-0004

Keywordsannual gain, juvenile-mature correlation, gene diversity, group merit, optimisation, two-stage selection, stage-wise selection, flowering induction

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
annual gain, juvenile-mature correlation, gene diversity, group merit, optimisation, two-stage selection, stage-wise selection, flowering induction