Cryopreservation of Grammatophyllum speciosum Blume seeds by D cryo-plate method

Abstract

Grammatophyllum speciosum Blume (also known as tiger orchid) is in the family Orchidaceae and native to Thailand. It is an epiphytic and occasionally a lithophytic orchid. Moreover, it can grow to a length of 2.5 m. This orchid has high consumption; while, the abilities of cultivating this orchid are too low, leading to low population and genetic diversity. In this study, we focus on the development of cryopreservation by D cryo-plate method for G. speciosum seeds. Encapsulation was compared between 3% (w/v) alginate solution (normal method) and 3% (w/v) alginate solution supplemented with loading soliton (modified method), then polymerized with 100 mM of CaCl2 for 20 min. The encapsulated seeds were dehydrated by using 3 different methods which are a laminar air-flow cabinet, silica gel, and drying bead with the same exposure times (0, 30, 60, 90, 120, 150, and 180 min). The moisture content from modified method with silica gel and drying bead can decrease to 35 and 22% in 120 min, respectively. After cryopreservation, encapsulated seeds were cultured on ½ MS medium. The viability results from tetrazolium test revealed that silica gel gave high viability rate up to 87.22% and drying bead gave 58.25% from 120-min exposure time.