Effect of nitrogen sources on shoot bud differentiation ofDioscorea deltoidea Wall. callus cultures

Tuber callus by subculture ofDioscorea deltoidea Wall, was grown with different sources of nitrogen on N-free Murashige and Skoog’s basal media supplemented with a high level of kinetin (1, 3, 6, 9 and 12 ml 1^-1) and low concentration of auxin (0.01 mg 1^-1 2,4-D) for shoot bud differentiation. Shoot and root differentiation was observed only in the case of ammonium nitrate. Other sources of nitrogen failed to produce shoot bud differentiation except in the case of ammonium citrate where tissues were slight green in colour and were recognizable as pro-embryo.