The 2012 ASHS Annual Conference

Orchids represent one of the most important ornamental crops and sales have increased for the past 15 years. Cryopreservation is a biotechnology tool that plays an important role in international plant conservation programs and in preservation of the world’s genetic resources.  Vitrification has been the most common method used in orchid seed cryopreservation.  The beneficial use of phloroglucinol and Supercool X-1000^® has been reported to enhance the recovery of protocorms and shoots vitrified in cryopreservation protocols. The objectives of this study were to evaluate the effect of the PVS2 vitrification solution at different exposure times either alone or combined with phloroglucinol and Supercool X-1000^® for cryopreservation and subsequent in vitro germination of the hybrid Dendrobium Dong Yai seeds. The experiment was divided into two phases.  The first phase aimed at finding the best exposure time for PVS2 by exposing seeds to 30, 60, 120, 240, and 360 minutes.  The second phase aimed at analyzing the effect of cryoprotectants solutions in enhancing seed survival and germination using the best PVS2 exposure time. About 2,000 mature seeds of Dendrobium Dong Yai were surface disinfected and placed in Petri dishes containing P-723^® culture medium.  Treatments consisted of the absence or presence of the vitrificant solution PVS2, with or without 1% phloroglucinol (w/v) and 1% Supercool X-1000^® (w/v).  Protocorm germination was evaluated under a stereoscope four weeks after treatments were initiated. Five treatments with five replicates were used in each experiment and the second experiment was repeated. Seed germination data was normalized using square root transformation and subjected to analysis of variance (ANOVA), with means compared using Tukey test (α = 0.05). The use of PVS2 during 60 minutes resulted in germination percentage of 51%, while the addition of 1% phloroglucinol increased germination to 79.3%.  Antioxidant properties of phloroglucinol may have contributed to seed survival by reducing oxidative stress in Dendrobium dong yai embryos during the PVS2 exposure. Therefore, the use of PVS2 during 60 minutes with 1% phloroglucinol is recommended for ultra low temperature seed conservation of this commercial hybrid orchid.