Abstract
Medicago polymorpha is a herbaceous legume that can be a useful pasture plant, in particular, in regions with a Mediterranean climate. The genetic variation in 120 lines of M. polymorpha sampled from five regions in Tunisia was characterized on the basis of 16 morpho-phenological characters. Results from analysis of variance (ANOVA) showed that differences among populations and lines existed for all traits, with population explaining the greatest variation for measured traits. The populations of Enfidha and Soliman were the earliest flowering, while those of El Kef, Bulla Regia and Mateur were the latest. El Kef and Mateur exhibited the highest aerial dry weight while the lowest value was found for Soliman. Moderate to lower levels of heritability (H²) were registered for investigated traits. There was no significant association between pairwise population differentiation (QST) and geographical distances. Studied lines were clustered into three groups with 59 for the first group, 34 for the second group, and 27 lines for the third group. The lines of the first two groups showed the largest length of stems while those of the second group had the highest number of leaves. The variation of quantitative traits among populations was influenced by the altitude, temperature and relative humidity. Overall, the high levels of within population variation and the lack of correlation between population differentiation and geographical distances suggest a potentially important rate of long-distance seed dispersal and confirm the role played by natural selection in the population structure of Tunisian populations of M. polymorpha. Key words: Medicago polymorpha, populations, quantitative traits, population differentiation, environmental parameters.
Highlights
Results from analysis of variance (ANOVA) showed that differences among populations and lines existed for all traits, with population explaining the greatest variation for measured traits
Results from the ANOVA showed that the variation of measured traits was explained by the effects of population and lines within population (Table 2)
Results from ANOVA support that the variation of the traits was explained by population and lines nested within population effects
Summary
The genus Medicago, with about 87 species of herbs and shrubs widespread from the Mediterranean to central. In Tunisia, the genus Medicago is well represented and it is an extremely rich and diverse gene pool (Seklani et al, 1996). Burr Medic (Medicago polymorpha) is an annual herbaceous legume, diploid (2n = 14) and self-compatible species. M. polymorpha can be a useful pasture plant, in particular, in regions with a Mediterranean climate (Salhi Hannachi et al, 1998). M. polymorpha is a species of Mediterranean origin, but its species range is wide spread throughout the world. In Tunisia, M. polymorpha grows in a range of environments from humid to upper arid stages (Abdelkefi et al, 1996)
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