In vitro propagation of Gladiolus hybridus Hort.: Synergistic effect of heat shock and sucrose on morphogenesis - Micropropagation of gladiolus

Three cultivars (cvs.) of Gladiolus hybridus Hort., namely 'Her Majesty', ' Aldebaran' and 'Bright Eye' were successfully micropropagated. The cultures were established using intact cormels or segments of cormels and infloresc ence axes on Murashige and Skoog (1962; MS) medium. The response depended o n media supplements; both callus formation or direct induction of shoot bud s was observed. Shoot differentiation from callus could be obtained on MS m edium containing 1.0 mu M BA (6-benzyladenine) and 10.0 mu M NAA (alpha-nap hthalene acetic acid) in all three cultivars. The same could be achieved by giving a heat shock (HS; 50 degrees C, 1h) to callus cultures (in case of 'Her Majesty' and 'Aldebaran' only) maintained on the basal medium. In thes e two cultivars, high sucrose concentration (0.232, 0.290 or 0.348 M) also favoured growth and proliferation of shoot cultures on a plant growth regul ator-free medium at 20 degrees C in comparison to the cultures kept at 25 d egrees C. On the other hand, shoot cultures maintained on the basal medium at 25 degrees C containing normal (0.058 M, i.e., 2.0%, w/v) sucrose concen tration responded similar to those maintained at 20 degrees C on a high suc rose medium; reduced response was observed on normal sucrose containing med ium at 20 degrees C. Heat shock enhanced shoot proliferation in the culture s maintained on basal medium, but induced prolific rooting in shoot culture s, within 5 days of HS, on high sucrose (optimum 0.232 M) medium. While the number of roots increased at higher sucrose concentrations in the medium i n case of cvs. 'Her Majesty' and 'Aldebaran', the same was found to be inde pendent of sucrose concentration in cv. 'Bright Eye'. Generally the rooted plants produced on high sucrose (0.232 M) medium in comparison to medium wi th normal sucrose concentration showed better survival (ca. 90% as against 40%) in the soil.