Morphophysiological aspects of dormancy in the dispersal unit of Atriplex cordobensis

The factors involved in the dormancy of dispersal units of Atriplex cordobe nsis were investigated. The chemical composition and the presence of a mech anical barrier were ascertained in bracts of the dispersal unit. The presen ce of Na, Cl and saponins inhibit partially the germination of seeds. Histo logical studies revealed strongly thickened and lignified walls of epiderma l and subepidermal cell layers. These may constitute a mechanical barrier t o water permeability and, therefore, prevent germination of the dispersal u nit.