Viability tests on the seeds of Rafflesia arnoldii R.Br. and R. patma Blume

Some of Rafflesia species are holoparasites that are threatened by habitat loss. The Center for Plant Conservation Botanic Gardens LIPI has been pioneering ex situ conservation using grafting methods. However, ex situ conservation using seed innoculation has proven to be a challenge. Studies on viability testing of Rafflesia seeds aims to ensure viable seeds for supporting ex situ seed innoculation conservation programs. The aims of our recent research were: (1) to investigate the morphological characters of the seeds and (2) to determine a method for viability testing. The seeds of R. arnoldii and R. patma were used in this research. Morphological characters of the seeds were observed under a binocular microscope. The viability test using bioassay procedures was as follows: (1) reagent preparation; (2) pre-staining; (3) embryo exposure; (4) staining, and (5) assessment. The research resulted in: (1) morphological description of the characteristics of Rafflesia seeds, i.e. seeds of R. arnoldii are 2-3-times larger than those of R. patma and that seeds of the two species have distinct testas, and (2) techniques for bioassay viability testing of Rafflesia seeds, i.e. the viability test resulted in an estimated viability percentage of 78.75 ± 4.75 % (R. arnoldii seeds) and 93.29 2.67 % (R. patma seeds).