IN-VITRO PROPAGATION OF GENTIANA-CERINA AND GENTIANA-CORYMBIFERA

The micropropagation of Gentiana cerina and G. corymbifera was investi gated. Cultures were initiated from axillary shoots or seed. Seeds of G. corymbifera germinated on a Murashige & Skoog (MS) medium containin g 100 mg/litre gibberellic acid (GA(3)) with 54% of the seed germinati ng within 70 days. In the absence of GA(3) germination did not exceed 5%. Both species proliferated shoots on MS medium supplemented with 6- benzylaminopurine (BAP). For G. cerina there was no significant differ ence in proliferation rates for BAP concentrations between 0.05 and 0. 5 mg/litre. In contrast G. corymbifera gave highest multiplication rat es on 0.2 mg/litre BAP. Addition of 1 mg/litre GA(3) to the medium gav e improved proliferation compared to treatments in which GA(3) was abs ent. The best treatment for G. cerina resulted in a shoot multiplicati on rate in excess of 7-fold after 50 days whereas for G. corymbifera t his increase was more than 3-fold. Root initiation occurred on MS medi um supplemented with indole-3-butyric acid (IBA). In both species the frequency of explants with roots increased with increasing IBA concent ration, but at IBA greater than or equal to 1 mg/litre and 3 mg/ litre for G. cerina and G. corymbifera respectively a high proportion of th e plants developed a basal callus. Survival of the G. cerina plants du ring acclimatisation was related to IBA concentration but survival was unrelated to IBA concentration for G. corymbifera. G. cerina survival rates decreased from 80% with up to 0.3 mg/litre IBA to c. 5% at the highest rate of IBA. For G. corymbifera average survival of plants aft er acclimatisation was just over 20%. Thus root initiation with 0.3 mg /litre IBA can be recommended for both species.