IN VITRO MORPHOGENIC RESPONSE OF ORCHID BY USING DIFFENENT EXPLANTS

Abstract

Orchid is an ornamental plant with high commercial value. Since, conventional propagation method si not competent ot produce sufficient planting materials for commercial cultivation and also seed propagation results ni unwanted heterozygous types, vegetative propagation by means of in vitro culture is an essential for rapid multiplication of orchids to meet the current market demand. This study was aimed ot select the suitable type of explants for ni vitro micropropagation of orchid. Young mother plants of Vanda orchid were collected from the net house subsequently nodal portion with auxiliary buds, leaves and stem were separated from these plants. Different types of 1cm long explants namely single nodal segments, base and tip portions (0.5 cm width) of leaves and stem segments (entire and vertically cut into half) were excised from these plant parts and then surface sterilized with 20% of sodium hypochlorite (5.25% active ingredients) for 30 min. Subsequently they were cultured on the MS basal medium supplemented with 2.0 mg/l BAP and 0.2 mg/l NAA to evaluate ni vitro morphogenesis. Result revealed that highest survival rate and ni vitro response (88.8%) were significantly (P<0.05) high ni light green immature nodal segment explants. Within four weeks of culture, mature leaf segments failed ot show any in vitro response. Immature leaf segments showed moderate in vitro response (33.3-44.4%) and survival rate (55.5%) was higher ni immature leaf tip portions than base portions (44.4%). Meanwhile stem segment explants showed very low survival rate (22.2%) and ni vitro response (11-22%). Within 4weeks of culture, creamy white ni colour swelling was observed ni nodal explants. Subsequently, nodules like structures were formed ot initiate shoot buds on nodal portions after 8 weeks of culture. The result indicated that nodal segments were found to be the best for in vitro plant regeneration as compared to leaf and stem segment explants