DEGRADATION OF EXOGENOUS INDOLE-3-BUTYRIC ACID AND RIBOFLAVIN AND THEIR INFLUENCE ON ROOTING RESPONSE OF PAPAYA INVITRO

Varying concentrations of riboflavin were added to a De Fossard et al. (1974) basal medium containing 10-mu-M IBA and the effect on adventitious root initiation on shoots of Carica papaya L. was studied. Ninety percent root initiation occurred in 11 days when 1-mu-M riboflavin was added to the culture medium. Smaller rooting percentages were observed and roots emerged more slowly with riboflavin concentrations greater and less than 1-mu-M. Tissue culture media were maintained at 27-degrees +/- 1-degrees-C in either darkness or 12-h photoperiods for 28 days, and concentrations of riboflavin and IBA were measured at regular intervals using HPLC analysis. In a De Fossard et al. (1974) basal medium, riboflavin concentrations (0.1, 1.0, 10.0-mu-M) decreased rapidly in light and were independent of the presence of IBA. IBA concentration steadily decreased when media was placed in light, and increasing riboflavin concentrations accelerated the reduction of IBA levels. Concentrations of IBA and riboflavin were stable with dark incubation.