Large-scale photoautotrophic micropropagation in a scaled-up vessel

A scaled-up culture vessel for the large-scale micropropagation has been designed and the method for the large-scale micro propagation of Eucalyptus under photoauto trophic condition (sugar-free medium) using this scaled-up culture vessel with forced ventilation (SV-treatment) is described. Growth, multiplication, epicuticular wax content, stomatal function of plantlets and transpiration rate and ex vitro survival of the plants grown under SV-treatment were studied and compared with those of the plantlets grown in a Magenta-type vessel with natural ventilation and under photomixotrophic condition (30 g l ^-1 sucrose in the medium). Results revealed that fresh and dry mass in plantlets grown under SV-treatment were significantly higher than those of plantlets from Magenta type vessel. Multiplication was enhanced and normal stomatal closing and opening were observed in the leaves of plantlets grown in scaled-up vessel. Epicuticular leaf-wax content was significantly higher compared with that of the leaves grown in Magenta type vessel. The anatomical study showed well-organized palisade and spongy mesophyll layers for leaves grown in SV-treatment. Importantly after transplanting ex vitro, plantlets survived well without any specialized ex vitro acclimatization treatment. This was because they were better able to control transpiration and thus lost less water and showed no signs of wilting. In contrast, plantlets cultured in Magenta type vessel had open stomata which were not functional, showed a higher transpiration rate and uncontrolled and rapid water loss immediately after transferring ex vitro. Minimization of large-scale plantlet production cost by using scaled-up vessel is also discussed in this article.