1. INTRODUCTION Dracaena, commonly known as Dragon tree belongs to family Dracaenaceae. The generic name is derived from the Greek word ‘drak<strong>in</strong>ia’ mean<strong>in</strong>g the dragons blood. It consists of about 40 species, some of them be<strong>in</strong>g grown as ornamentals. They have orig<strong>in</strong>ated from tropical regions of Asia <strong>and</strong> Africa. Dash<strong>in</strong>g <strong>dracaena</strong> is a high value commercial foliage ornamental plant <strong>in</strong> the national <strong>and</strong> <strong>in</strong>ternational floricultural market. It occupies a position among the top 10 pot plants <strong>in</strong> the global floriculture trade. Cordyl<strong>in</strong>e, orig<strong>in</strong>ated from the tropical <strong>and</strong> sub-tropical regions of the world, East Himalayas, Ch<strong>in</strong>a, Malaysia <strong>and</strong> North Australia. Cordyl<strong>in</strong>e commonly called as cabbage palm <strong>and</strong> the generic name is derived from Greek word ‘Kordyle’ mean<strong>in</strong>g club or cudgel referr<strong>in</strong>g to the shape of the roots (Pal, 2006). The cordyl<strong>in</strong>e genera belongs to family Laxmanniaceae (Liamas, 2003). Cordyl<strong>in</strong>e is very closely related to <strong>dracaena</strong> <strong>and</strong> differs from the latter only <strong>in</strong> the structure of ovary. Several species of cordyl<strong>in</strong>e are commonly known as <strong>dracaena</strong> (R<strong>and</strong>hawa <strong>and</strong> Mukhopadhyay, 2004). It is a long slender bush up to 3m <strong>in</strong> height <strong>and</strong> priced for its rich coloured foliage, <strong>in</strong>clud<strong>in</strong>g variegated forms. Cordyl<strong>in</strong>es <strong>and</strong> <strong>dracaena</strong>s are excellent pot plants <strong>in</strong> their juvenile state <strong>and</strong> some of them are also suitable for grow<strong>in</strong>g <strong>in</strong> borders <strong>and</strong> shrubberies under a mild climate, for shade gardens <strong>and</strong> greenhouse. At young stage of growth most of the species are widely used for table decorations. The magnificent, delightful <strong>and</strong> charm<strong>in</strong>g foliages of <strong>dracaena</strong>s are used <strong>in</strong> floral designs, bouquets, wreaths, dried arrangements <strong>and</strong> <strong>in</strong>door garden<strong>in</strong>g. The plant commonly found <strong>in</strong> houses, offices, shops, banks, hotels, restaurants, clubs, hospitals <strong>and</strong> schools <strong>and</strong> sometimes several plants are grouped <strong>and</strong> grown <strong>in</strong> terrariums, bottles, bowls, dishes, troughs <strong>and</strong> aquarium cases as elegant table decorations (Beura et al.,2007). Ornamental foliage plants from the world’s tropical <strong>and</strong> subtropical regions provide the basis for today’s foliage plant <strong>in</strong>dustry. The trade of ornamental foliage plants is comparatively a new venture <strong>in</strong> India <strong>and</strong> is ga<strong>in</strong><strong>in</strong>g popularity. As foliage plants are produced primarily for <strong>in</strong>terior decoration or plantscap<strong>in</strong>g, a cont<strong>in</strong>ued desire for multicolour foliage plants <strong>in</strong> <strong>in</strong>terior designs has resulted <strong>in</strong> a dramatic <strong>in</strong>crease <strong>in</strong> ornamental foliage plant production. At present, most of the foliage plants are exported to Germany, USA, Netherl<strong>and</strong>s, U.K., Italy <strong>and</strong> Japan, constitut<strong>in</strong>g nearly 60 percent of India’s floricultural exports (Ray et al., 2006). Tissue culture technique is now used for propagation of numerous ornamental plants for commercial purposes <strong>and</strong> there has been a big market dem<strong>and</strong> for exotic cultivars of <strong>dracaena</strong> <strong>and</strong> cordyl<strong>in</strong>e. These foliage plants are propagated commercially by vegetative methods by division of suckers <strong>in</strong> species produc<strong>in</strong>g suckers or more frequently by air layer<strong>in</strong>g <strong>and</strong> from node or term<strong>in</strong>al cutt<strong>in</strong>gs of the stem. The old stems are cut <strong>in</strong>to bits, each conta<strong>in</strong><strong>in</strong>g one node <strong>and</strong> then placed horizontally <strong>in</strong> moist s<strong>and</strong> <strong>in</strong> seed pans with the bud po<strong>in</strong>t<strong>in</strong>g upwards. The s<strong>and</strong> is kept just moist <strong>and</strong> the cutt<strong>in</strong>gs soon develop roots <strong>and</strong> start grow<strong>in</strong>g. Term<strong>in</strong>al cutt<strong>in</strong>gs also root, but the plants are not as good as those from node cutt<strong>in</strong>gs. The rate of multiplication is very slow as term<strong>in</strong>al cutt<strong>in</strong>g produces a s<strong>in</strong>gle plant <strong>and</strong> a matured <strong>dracaena</strong> plant produces 3-4 plants through stem cutt<strong>in</strong>gs or 2-3 suckers at the base. The traditional method produces less number of plants from a s<strong>in</strong>gle plant <strong>and</strong> also takes more time. Micro propagation technique overcomes these issues by giv<strong>in</strong>g more number of plants with<strong>in</strong> a short period of time. Micropropagation is a very economical means of multiply<strong>in</strong>g a desirable plant species when time, space <strong>and</strong> personnel are often serious constra<strong>in</strong>ts. It is also possible to produce disease free, uniform propagules at a required quantity <strong>and</strong> at an appropriate time of the year. The use of tissue cultured plant<strong>in</strong>g material can rationalize foliage culture because direct plant<strong>in</strong>g <strong>in</strong>to pots without special manipulation for a large harvest of propagule is possible. Moreover, the conventional mode of propagation enables us to produce only four daughter plants from one mother plant (Khan et al., 2004). Therefore micro propagation by means of <strong>in</strong> vitro techniques is of great <strong>in</strong>terest <strong>in</strong> order to speed up the propagation rate <strong>and</strong> to reduce the need for mother plants (George <strong>and</strong> Sherr<strong>in</strong>gton, 1993). The present study aims to
optimize the micro propagation protocol for cordyl<strong>in</strong>e <strong>and</strong> <strong>dracaena</strong> <strong>in</strong> order to make the propagation feasible <strong>and</strong> economical under the follow<strong>in</strong>g objectives, 1. To st<strong>and</strong>ardize the surface sterilization of explants. 2. To identify a suitable explant for shoot <strong>in</strong>itiation. 3. To identify suitable growth regulators <strong>and</strong> their concentration for shoot multiplication <strong>and</strong> root<strong>in</strong>g. 4. To f<strong>in</strong>d out suitable media for harden<strong>in</strong>g <strong>and</strong> ex vitro root<strong>in</strong>g of micropropagated plantlets.
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