Conditions were established for efficient plant regeneration from cotyledon explant calli in different cultivars of Brassica juncea, B. campestris and B. carinata on Murashige & Skoog's (MS) medium supplemented with various combinations of cytokinins and auxins.
Regeneration frequency, however, varied with genotype and the different growth hormone combinations in media. Almost in all species, MS medium with zeatin (1.0mg 1 -t) and IAA (0.1 mg 1-t ) was found to be best for shoot organogenesis followed by the ones containing high kinetin (2.0mg 1 -t) and low IAA (0.02 or 0.2mg l -t) concentrations. On these media, the cotyledonary explants invariably underwent callusing followed by multiple shoot formation, which could be separated and subcultured for further propagation. Number of shoots per cotyledon explant cultured varied from 0 to as many as 50. In B. juncea and B. campestris, the regeneration frequency declined sharply in the absence of auxin in medium. BAP in combination with NAA yielded no or a reduced number of shoots. Shoot organogenesis also declined with the reduction in photoperiod from continuous light to 16 hours. Shoots were easily rooted during prolonged incubation on the same medium and whole plants were transferred to pots in the greenhouse and grown to maturity.