EFFECT OF SEED PRECONDITIONING AND CULTURE UNDER DIFFERENT LIGHT INTENSITIES ON CALLUS INDUCTION AND REGENERATION IN EXCISED COTYLEDON CULTURES OF MUNGBEAN (VIGNA-RADIATA (L) WILCZEK)

Different seed preconditioning treatments and light intensities were t ested for their effect on the callus induction and regeneration in cot yledon cultures of mungbean (Vigna radiata (L.) Wilczek). There were s ix preconditioning treatments evaluated including imbibition in steril e distilled water, inoculation in plain agar, and inoculation in 6-ben zyladenine (6-BA) supplemented media over a varing period of time. The cultures were incubated in two light intensity conditions; namely, fu ll light (50 mu mol m(-2) sec(-1)) and minimum light (8.5 mu mol m(-2) sec(-1)). Results of the study showed that (1) plain imbibition of se eds in sterile distilled water for 16 hours was more favorable for reg eneration than preconditioning with 6-BA enriched media, and (2) preco nditioning of callus formation and better callus growth. Other importa nt observation was the differential response to plantlet regeneration under different regeneration media. Plantlet regeneration in B5 basal medium supplemented with 1.0 mu M NAA and 9.0 mu M 6-BA was relatively higher than the other regeneration media under full light intensity w hile Murashige and Skoog (MS) basal medium and MS basal medium supplem ented with 1.0 mu M NAA and 9.0 mu M 6-Ba had highter plantlet regener ation under minimum light intensity.