Document Type



Alfalfa, falcata, heritability, genetic correlations


The complex genetics of autotetraploid alfalfa (Medicago sativa L.) make additive genetic variance component estimation difficult. Halfsib family variances often are used to estimate additive genetic variances and, by extension, narrow sense heritabilities and additive genetic correlations. These estimates contain a portion of the dominance variance. Using such calculations, in conjunction with parent-offspring covariance estimates, the dominance component can be separated from the additive genetic component. This is rarely done. This study reports average estimates across 30 populations, of both additive and dominance variance component estimates based on between halfsib family variance and parent-offspring covariance for biomass yield, plant height, regrowth, plant width, plant growth angle, vegetative density, and maturity during each of three harvests. We consistently found negative dominance variance estimates. Based on previous theory, this suggests epistatic interactions are a noticeable component of most traits measured. Assuming no epistasis leads to inflated narrow sense heritability estimates when compared with estimates based on parent-offspring regression. Assuming no epistasis and no dominance variance, weighted averages of additive genetic variance between halfsib family and parent-offspring effects revealed plant width and vegetative density additively correlated with biomass yield. Peak photoperiod maturity had a nonsignificant negative additive correlation with biomass yield. Plant height had no additive correlation with biomass, in contrast to the strong phenotypic correlation observed. Additive genetic correlations for the same traits measured during different harvests in most instances were highly correlated. On average, third harvest heritabilities were greatest. Our results suggest selecting plants based on later season performance (August - October) is most effective for Iowa environments.

Publication Date

January-December 2007

Journal Title

Journal of the Iowa Academy of Science





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© Copyright 2008 by the Iowa Academy of Science, Inc.



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