Effect of capsule maturity and desiccation time on viability of Taiwan native orchid, Bletilla formosana seeds (Orchidaceae) after cryopreservation

Desiccation method has been successfully applied to the cryopreservation of Bletilla formosana seeds (Orchidaceae). This study investigated the effects of capsule maturity and desiccation time on the viability of B. formosana seeds after cryopreservation. Seeds with various degrees of maturity (60, 70, 80, 90, 100, and 110 days after pollination; DAP) were used as the test samples and dried for 0 and 24 h prior to cryopreservation. The results demonstrated that the germination percentage of the 110 DAP seeds with 24 h desiccation pretreatment was the highest (96.7%). The 110 DAP seeds were then used to further test the effects of various desiccation time (0, 2, 4, 6, 8, and 24 h) on the viability of the seeds after cryopreservation. The results demonstrated that when seeds were dried for 4-24 h prior to preservation, the water content was reduced to 10.8-0.6% (w/w), and the germination percentage (86.7-95.5%) were significant difference higher than un-desiccation treatment after cryopreservation and thawing to room temperature. The seeds of B. formosana were highly tolerant to desiccation, thus, they should be orthodox seeds and are suitable for long-term storage through cryopreservation.