MICROPROPAGATION OF VANILLA : A FOREMOST ORCHID SPICE CROP OF HUMID TROPICS

摘要

Vanilla belongs to the family Orchidaceae is an important humid tropical orchid spice crop cultivated for its pleasant odour vanillin. It is also called as vainilla in Spanish is a diminutive of vaina "sheath, vagina, pod", motivated by the sheath like shape of fruit. There is a ever growing demand for natural flavour all over the world, and natural vanilla i.e. vanillin is one of the delicacies among the products that have a bright future in the global spice trade (Goodenough 1982; Ranadive 1994). Vanilla planifolia is the only fruit-bearing orchid to produce an edible fragrance substance Vanillin' (4-hydroxy 3-methoxy benzaldehyde) of commercial importance with a world wide annual production of 120 tonnes of natural vanillin which is 1% of total world wide vanillin production. It's rarity makes natural vanillin extremely valuable more than 10,000 per kilo dollar. This orchid crop offers excellent scope for development in the tropical high rainfall regions in southern India. Vanilla a vine orchidis generally propagated by stem cuttings. However, this method of propagation is having certain drawbacks with poor yield (Ayyappan 1990, Knorr et at. 1993). As in case of other economically important plants and horticultural plants, tissue culture methods have been adopted for micropropagation of this orchid (Stafford, 1991; Knorr et al. 1993). In vitro multiplication of V. planifolia has been reported through the culture of callus masses (Gu et aL 1987; Davidonis ET Knorr 1991), protocorms, roottips (Phillip a Nainar 1986), and axillary bud explants (Kononowicz ET Janick 1984; George a Ravishankar 1997). According to most of these reports production of micropropagated plants of Vanilla for commercial propagation requires long periods not less than 6-7 months. So producing elite vanilla plants for successful commercial propagation is necessary. In the recent past attempts were made to develop a rapid method for efficient shoot multiplication ofvanilla by using the various combinations of plant growth regulators and silver nitrate etc and the same will be given in this report.