Location: Dairy Forage ResearchTitle: Selection methods in forage breeding: a quantitative appraisal Author
|Vilela De Resende, Marcos Deon|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2013
Publication Date: 9/1/2013
Publication URL: http://handle.nal.usda.gov/10113/62436
Citation: Resende, R., Casler, M.D., Vilela de Resende, M. 2013. Selection methods in forage breeding: a quantitative appraisal. Crop Science. 53:1925-1936. Interpretive Summary: The discipline of forage breeding spans many species with widely different biological characteristics. Some are perennial, others are annual; some produce seed by selfing, others by outcrossing; and some have very complex mating systems that allow individuals to propagate themselves via seed. A wide range of breeding methods have been developed for use in forage breeding programs and there is little information available regarding the efficiency of these methods, expressed as genetic gain per year. A direct comparison of the efficiency of eight common breeding methods for perennial forage crops revealed only small differences when heritability of the trait under selection is high. For low heritability, a very common case, modern BLUP (best linear unbiased predictor) methods were superior to all other breeding methods. BLUP-based methods were superior because they make use of both among-family and within-family information to increase the accuracy of predicted breeding values. These results will be of value to forage breeders worldwide.
Technical Abstract: Forage breeding can be extraordinarily complex because of the number of species, perenniality, mode of reproduction, mating system, and the genetic correlation for some traits evaluated in spaced plants vs. performance under cultivation. Aiming to compare eight forage breeding methods for direct selection gain and correlated response, different scenarios of trait heritability and genetic correlation have been evaluated based on deterministic equations of accuracy applied to half-sib progenies evaluated in spaced-plant trials, sward-plot trials, or both. Relative efficiency for each method was given in relation to individual selection. Methods differed most when heritability was lower than 0.3, which coincides with the majority of the situations met by forage breeders. Genetic gain of BLUP-based methods was superior to all other methods for trait heritability lower than 0.3, independent of field trial plot evaluation. BLUP-based methods have also shown higher efficiency when the genetic correlation between spaced-plant and sward-plot trial evaluations of a trait was lower than 0.7 and indirect-trait heritability was lower than 0.3. The choice of forage selection breeding method should be based on the mode of reproduction and target-trait heritability. The benefits of BLUP-based selection methods should receive more serious consideration by forage breeders.