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An attempt has been made to study the potential of mutagenic effects of gamma rays and sodium azide (NaN3) on the meiotic cells of Vigna unguiculata (cowpea). Cowpea being a self-pollinated vegetable crop has very limited genetic variability therefore induced mutation can provide additional source of mutation in recent plant breeding programmes. Chromosomal aberrations like unorientation, multivalents, laggards, bridges, micronuclei, stickiness and precocious movement etc. were noticed in mutagen treated populations. Chromosomal aberrations were found to be correlated with the concentrations of physical and chemical mutagens individually as well as in combination. On the basis of our experimental results it can be concluded that the combined treatment proved to be more effective in inducing abnormalities and pollen sterility as compared to individual treatment sets.

The occurrence of polytenic nuclei in the anther tapetum of field grown variety K 5269 of a bean species, Vigna unguiculata has been recorded. There are pronounced polytene nuclei with chromocenters unassociated with chromatin bundles. In comparison to polytenic nuclei of other plants they were relatively smaller with a small nucleolus. These features of polytenic nuclei suggest low level of endoreduplication in Vigna unguiculata.