Progress in a Programme for Breeding Resistant Mutants of Field Bean (Vicia faba L.) to the Southern Cowpea-Weevil (Callosobruchus maculatus F.) by the Use of Gamma Rays and Conventional Breeding

Mutants, produced after the application of seed treatment by 6060 Co gamma ray doses varing from 500 to 5000 rad, as well as nonirradiated lines of field bean (Vicia faba L.), with different seed coat colours showed-across three seasons-the higher resistance of the white seeded lines and mutants against infestation by the southern cowpea weevil (Callosobruchus maculatus F.) an insect which attack the pods after pod setting or during the green pod stage and while the crop is maturing or in the store. The brown seeded varieties, lines and mutants tested in addition to an introduced purple variety showed higher susceptibility-to the same weevil-indicating a possibility for chemical resistance, of the bean variety an assumption which needs more investigation. Methods used and results obtained have been discussed in the light of the relevant literature.