Cryopreservation and low-temperature storage of seeds of Tillandsia species (Bromeliaceae) with ornamental potential.

Tillandsia (Bromeliaceae) species have high endemism, and due to their strong ornamental potential, predatory extraction is threatening the extinction or drastic population reduction of many of them. In light of this scenario, it is necessary to find strategies for the conservation of these endangered species. The objective of this study was to evaluate two seed preservation strategies (freezing at - 5 °C and cryopreservation at - 196 °C) for 20 Tillandsia species occurring in the state of Bahia. We initially evaluated the morphometry, thousand-seed weight, and water content, followed by tests of germination and desiccation. After selecting the best result of the germination test (Germitest paper and incubation at 30 °C) and desiccation (3 h on silica gel), we established conservation tests utilizing two temperatures (freezing at - 5 °C and liquid nitrogen at - 196 °C), with storage times of 1, 7, 30, 180 and 450 days. Analysis of variance indicated that the 20 species had different behaviors when submitted to the two temperatures and different storage times. After 450 days there was a reduction in the germination percentage and germination speed index (GSI) of all the species studied when the seeds were preserved in the freezer. The storage in liquid nitrogen was efficient for the preservation of Tillandsia seeds when dried to a moisture content of approximately 7%. Our results support the establishment of a cryobank for Tillandsia to conserve these endemic species.