Variation in Panicum maximum: A Comparison of Sexual and Asexual Populations

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Abstract
Twenty-five predominantly asexual and 3 highly sexual (50% or more sexual) populations of guineagrass (P. maximum Jacq.), referred to as asexual and sexual groups for brevity, were studied for variability in several vegetative and reproductive characters as well as for 7 allozyme loci. Population means and coefficients of variation (CV) for a majority of characters showed significant diversity among populations. Comparisons of within-population variability using CV and allozyme polymorphisms showed that the sexual lines on the average have more variation than the asexual group, but within-population variability in the asexual group is such that a few even exceed the sexual group in heterogeneity. Estimates of heritability based on parent-progeny regression and on character associations were not significantly higher for the asexual group. These findings are discussed in relation to the classical views about genetic uniformity of asexual populations and clearly suggest that facultative and variable levels of apomixis would require a population study of the role of sex in evolution as well as in crop improvement methods.

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