Degree of moisture in seeds for the cryopreservation of orchids native to Brazil

ABSTRACT: The objective of this study was to determine the ideal moisture degree for the cryopreservation of Cattleya labiata Lindl. and Miltonia regnellii Rchb.f. orchid seeds. Orchid seeds were standardized in relation to the desired moisture degrees (4, 6, 8, 10, 12, and 15%) and were subjected to rapid freezing in liquid nitrogen (-196 °C) for 24 h; then, the seeds were defrosted and analyzed. For both orchid species, the seeds that were immersed in liquid nitrogen with 4% moisture content had the highest viability percentage, averaging 95% and 68% of viable seeds for C. labiata and M. regnellii, respectively. The seeds with 12% and 15% moisture content had no viable seeds. For the fresh mass of seedlings, there was no significant difference between moisture content treatments for either species.