Ease of Floret Tripping in Alfalfa: Quantitative Inheritance and Expected Genetic Gain
- Eric E. Knapp,
- Larry R. Teuber and
- John A. Henning
Breeding alfalfa (Medicago saliva L.) with florets that are easier for honey bees (Apis mellifera L.) to trip has been proposed as a means of increasing the efficiency of pollination and improving seed yield. The objectives of this study were to determine the mode of inheritance and develop breeding recommendations for ease of tripping. Thirteen plants were chosen at random from ‘CUF101’ and emasculated crosses were made in a 6 × 7 factorial mating design. Ease of tripping was evaluated on florets of the resulting progeny in the field at Davis, CA, in 1990 and 1991. Variance components were estimated with autotetraploid genetic models and used to predict expected genetic gain for different breeding methods. Variances due to both males and males × females were significant, whereas the variance due to females was not significant. Additive genetic variance was 9.15 x 10~6 and digenic genetic variances was 4.45 × 10−6. Narrow-sense heritability for ease of tripping on an individual plant basis was 34% (SE = 16%). Expected genetic gain per year was greater for phenotypic recurrent selection than for mass selection, half-sib family selection, half-sib progeny test selection, and among-and-within half-sib family selection. Phenotypic recurrent selection, based on a single year of evaluation, is recommended as the most efficient breeding method for improving ease of tripping of CUF101 alfalfa.
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