Mass propagation of Eucalyptus camaldulensis in a scaled-up vessel under in vitro photoautotrophic condition

A scaled-up culture vessel was designed for the large-scale photoautotrophic micropropagation of chlorophyllous plants. The culture vessel (volume 20 I) contained a plug cell tray with 448 plantlets, and had a forced ventilation system to supply CO₂-enriched air. A nutrient-reservoir was connected to the culture vessel from which nutrient solution was circulated to the culture vessel every 24 h. Nodal leafy cuttings of Eucalyptus camaldulensis L. were cultured photoautotrophically in this system without sugar in the nutrient medium, but with an enriched CO₂ concentration and a high photosynthetic photon flux. The growth and the net photosynthetic rate of the in vitro growth plantlets and the survival percentage of the plantlets after transplanting to ex vitro conditions were compared with those of plantlets grown photoautotrophically under natural ventilation in conventional small culture vessels (Magenta-type vessels; volume 0.4 I). Fresh and dry masses and net photosynthetic rate were significantly higher in plantlets grown in the scaled-up vessel compared to plantlets grown in the conventional small vessels (control). The environmental conditions created in this scaled-up vessel (with forced ventilation) also facilitated acclimatization in vitro. Importantly, after transplanting to the ex vitro condition, plantlets grew well without any specialized ex vitro acclimatization treatment. (C) 2000 Annals of Botany Company.