Cryopreservation of seeds from endangered Brazilian bromeliads - Dyckia brevifolia Baker and D. delicata Larocca & Sobral

This study aimed to evaluate the influence of different solutions that cryopreserve, in liquid nitrogen, seeds from Brazilian bromeliads species threatened with extinction, the Dyckia brevifolia Baker and D. delicata Larocca & Sobral. Ten treatments and four replicates per treatment were used, namely, without adding the cryoprotective solution and no immersion in liquid nitrogen; immersion in liquid nitrogen without adding cryoprotectant; 1 M glycerol; 2 M glycerol; 0.4 M sucrose; 0.8 M sucrose; PVS1; PVS2; PVS2 + 1% phloroglucinol and PVS3. The seeds remain frozen for 15 days until the evaluation of germination percentage, abnormal seedlings, germination speed index, and seedling length and dry mass took place. After cultivation in a greenhouse for six months, the length and the dry weights of the shoot and the root system were evaluated, as well as the total dry weight and the shoot/root ratio. Concerning the treatment without using cryoprotectants, D. brevifolia and D. delicata seeds attained, respectively, 92% and 79% of germination. Using cryoprotectants did not impair seed viability. Dyckia brevifolia seeds with 6.8% water content and Dyckia delicata with 8.9% can be cryopreserved in liquid nitrogen without needing cryoprotectant solutions.