Acclimatization of in vitro Germinated Seedlings of Tiger Orchid (Grammatophyllum speciosum Blume.) in Hydroponic Culture Using Dynamic Root Floating Technique (DRFT) with Chitosan Spraying

Abstract

In vitro seedlings of Grammatophyllum speciosum Blume. were transplanted to ex vitro acclimatization by growing in dynamic root floating technique (DRFT) hydroponic culture with two levels of nutrient ionic strength of KMITL (King Mongkut’s Institute of Technology Ladkrabang) formula. During acclimatization period of 125 days, plantlets were sprayed weekly with chitosan solution of 0, 10 and 15 ppm. The experiment was conducted under a glass-roof greenhouse during monsoon period (September-January) with high relative humidity, relatively low temperature, and low light intensity. Throughout the experiment, leaf number and leaf length were recorded for growth comparison of two nutrient strengths and different chitosan concentrations. Plant growth increased equally for all treatment combinations. The acclimatized plantlets were able to survive in 10-fold-diluted nutrient solution (75-87.5%) slightly better than in 5-fold dilution (66.7-75.0%) while chitosan treatment had no clear effect on plant survival. After harvesting, growth data of the orchid plantlets in two levels of nutrient strength with various concentrations of chitosan application were collected and analyzed for statistical differences. All leaf number, leaf length, root number and plant fresh weight were not significantly different.