In vitro PROPAGATION OF Sprekelia formosissima Herbert., A WILD PLANT WITH ORNAMENTAL POTENTIAL

Abstract

Vegetative propagation of Sprekelia (Sprekelia formosissima Herbert.) in natural conditions is limited because it produces only one bulb per year or none. The objective of this research was to generate an in vitro propagation protocol for this species to increase its commercial propagation rate without extracting the species from its natural habitat. Bulbs of 4 to 5 cm in diameter were used as disinfested donor explant material; 1 cm² explants were obtained from the cataphyll leaves with and without a portion of basal disc; these explants were established in MS medium supplemented with 8.87 μM of N⁶ benzyl adenine (BA) and 0.98 μM of indole-3- butyric acid (IBA). For shoot multiplication, bulblets obtained from the previous phase were used as explants and cultivated in MS medium with 2.5, 5, 10, 15 and 20 μM of BA combined with IBA at a 10:1 ratio (BA: IBA). Shoots obtained from multiplication were established in MS medium supplemented with 1, 2, 3, 4, and 5 % (w/v) sucrose to promote growth. Bulblets were rooted in MS medium supplemented with 0, 0.49, 0.98, 1.96, 3.93 and 7.8 μM of IBA. Once roots formed, they were transferred to soil to assess their acclimation. We obtained 89.1 % of aseptic explants, of which 86 % formed two shoots on the average. Multiplication of shoots increased as BA concentration increased in culture medium, and the best results (75 % of bulblets with shoots, 2.66 shoots per bulblet and 2.0 mm diameter shoots) were obtained with 20 μM BA. The best bulb growth in diameter (4.2 mm) and number of bulblet leaves (3.5) was obtained with 5 % sucrose. The use of 0.98 μM IBA resulted in greater rooting percentage (93.7) and number of roots per bulblet (2.0), which were 2.4 cm long on average. Up to 83 % of the bulblets survived acclimation. This protocol to micropropagate Sprekelia formosissima allowed the production of at least 96 bulblets from one mother bulb in a six months period of in vitro culture.