Morphological variability of fruit and chromosome numbers in Tunisian populations of Atriplex halimus L. (Chenopodiaceae)

Atriplex halimus L. (Chenopodiaceae) can be divided in two subspecies: the diploid halimus (2n=2x=18) and the tetraploid schweinfurthii (2n=4x=36). This was based on differences in morphology, with respect to habit, size, leaf shape and fruit morphology. Atriplex halimus L. is a perennial shrub used as a fodder in the and and semi-arid parts of North Africa and the Middle East. A. halimus is dominant in the semi-arid and sub-humid areas while A. schweinfurthii is more common in and areas. Natural populations of A. halimus L. exhibit large levels of plant morphological and physiological variability. However, little is known about the morphological variability of its fruits. We located and sampled ten populations of Atriplex halimus L. in Tunisia to assess their fruit diversity. Fruit shape, size, length, width, and weight, measured on samples collected from all ten populations, were highly variable suggested a height phenotypic variability in the natural populations of Atriplex halimus L. In another hand, chromosome numbers for five populations of Atriplex halimus L. from Tunisia were determined. Although the Tunisian populations originated from widely-separated sites of contrasting climatic conditions, the chromosome counts showed that all of them were tetraploid (2n = 4x = 36).