MASS-PROPAGATION OF COFFEE FROM PHOTOAUTOTROPHIC SOMATIC EMBRYOS

摘要

The somatic embryos of Coffea arabusta were cultured and different stage embryos (torpedo, precotyledonary, cotyledonary and germinated) were selected. When these embryos were grown photoautotrophically (in sugar-free medium with CO_2 enrichment in the culture headspace and high photosynthetic photon flux) for 60 days the dry mass of each of the cotyledonary and germinated embryos increased by up to 10% and 50%, respectively. In contrast, the torpedo and precotyledonary stage embryos lost at least 20-25% of their initial dry mass. Thus we have suggested that cotyledonary stage embryos can be considered as the earliest stage, which can be cultured photoautotrophically in order to develop plantlets. In this article we have also discussed about a specially designed large culture vessel with forced ventilation system for the mass-propagation of coffee plantlets. The cotyledonary stage embryos were selected and grown in this specially designed large vessel having temporarily root zone immersing system with the view of large-scale embryo-to-plantlet development under photoautotrophic condition. The growth and survival of the plantlets after 45 days of culture were studied and compared with those grown photoautotrophically in a RITA vessel (Vitr Pic, CIRAD) and in a Magenta-type vessel. Results revealed that fresh mass and dry mass of leaves and roots of plantlets developed in the specially designed large vessel were significantly enhanced compared with those of plantlets developed in a RITA vessel. The poorest growth of the plantlets was observed when grown in a Magenta-type vessel. The survival of the plantlets after transplanting ex vitro followed a similar pattern and was highest in the large vessel followed by that in RITA vessel and in Magenta-type vessel.