Effects of some growth regulators on in vitro tuberization in Dioscorea alata L. ?Brazo fuerte? and D. abyssinica Hoch.

Abstract

Nodal cuttings of Dioscorea alata L. 'Brazo fuerte' and D. abyssinica Hoch. were cultured in vitro to assess the influence of NAA on the production of microtubers. In D. alata, high concentrations of NAA (27 and 54 μM) favored the production of large microtubers, whereas the highest number of microtubers was obtained with 2.7 μM. D. abyssinica was found to be more sensitive to NAA since concentrations higher than 0.27 μM promoted the growth of callus on the root system. In this species, the production of the largest microtubers was obtained at 2.7 μM whereas the number of microtubers was not affected by any concentration tested. In D. alata, the effects of ABA and BAP were also evaluated. The weight of the microtubers increased with increasing concentrations of ABA. This effect, however, was observed only on expiants cultured under 8 h photoperiod, but not on those cultured under 16 h. Finally the presence of BAP at concentrations as low as 0.22 μM adversely affected the survival of the explants.