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Cryopreservation of Paphiopedilum javanicum seeds by encapsulation-dehydration

Petrus, E., Ripin, R., Molidin, D., Aziz, Z. A.
Acta horticulturae 2019 no.1234 pp. 181-188
Paphiopedilum, cryopreservation, encapsulation, nitrogen, seed germination, seeds, sodium alginate, sucrose, water content, Borneo
Paphiopedilum javanicum is one of five slipper orchids that can be found in the area around Mount Kinabalu in Malaysian Borneo. A cryopreservation method based on encapsulation-dehydration was established for the storage of P. javanicum seeds. To evaluate the effect of sucrose pretreatment, immature seeds encapsulated in 3% (w/v) sodium alginate beads (4-5 mm) were incubated in sucrose solutions with different concentrations (0.0, 0.2, 0.4, 0.6 and 0.8 M). For optimization of the duration of sucrose treatment, the encapsulated seeds were incubated in sucrose solution for different duration (1 to 4 days). To test the effect of moisture content, the seed-containing beads were dehydrated from 80 to 25% (fw basis). Cryopreserved seeds stored in liquid nitrogen consistently showed higher germination percentage as compared to those that were not placed in liquid nitrogen. When encapsulated seeds were pretreated with sucrose, the highest seed germination (49.4%) was observed when treated with 0.6 M sucrose. The best incubation period in sucrose solution was 3 days with 47.1% seeds being able to germinate. Finally, 25% bead moisture content gave the highest post-cryopreservation seed germination (54.5%). This study shows that the seeds of this species respond positively to encapsulation-dehydration cryopreservation.