The influence of exposure period to vitrification solution on seed germination and protocorm survival rate of Dendrobium cretaceum Lindl. was investigated. Seeds and protocorms were treated with PVS2 solution for 0, 10, 20, 30, 40, 50, 60, 70, 80 and 90 min before plugged into liquid nitrogen. The experiment was conducted following Completely Randomized Design (CRD) with ten treatments and four replicates. The exposure period to PVS2 solution had a significant effect on seed germination time and germination percentage of D. cretaceum seeds. Seed germination time varied from 5.25 to 8.50 days after treated with PVS2 solution. In addition, the seeds treated with PVS2 solution for 10, 20 and 90 min showed the highest germination percentage of 100.0 percent, which were higher than those treated for 80, 70, 40, 10, 50, 60 and 30 min (97.5, 97.5, 97.5, 95.5, 95.0, 75.0, and 75.0 percent, respectively). The use of the PVS2 solution for 90 min can be recommended as the most effective exposure time for cryopreservation of D. cretaceum Lindl. seeds. Furthermore, protocorms treated with plant vitrification solution for 10, 20, 30, 40, 50, 60, 70, 80 and 90 min before plugged into liquid nitrogen had a significant effect on survival percentage of protocorm. The highest survival rate was 91.3 percent when protocorms were treated with PVS2 solution for 90 min. Additionally, the protocorms treated with PVS2 solution for 80, 70, 60, 50, 40, 30, 20 and 10 min showed average survival rates were 90.0, 81.5, 78.5, 78.0, 67.8, 50.0, 33.5 and 10.0 percent, respectively.
