Abstract
The Brazilian Caatinga houses a number of cacti species, which are considered endangered due to human influence. Two of them, Melocactus zehntneri Braun ex Ritter f. and Cereus gounellei Luetzelb ex Schum k., are endemic of the Brazilian Caatinga. Cryopreservation can provide a means for long-term preservation of endangered plant material. The aim of this study was to evaluate the efficiency of cryoprotectants for the cryopreservation of seeds from these two species. The treatments consisted of immersing seeds in different cryoprotectant solutions and vitrification solutions before storage in liquid nitrogen (NL) at -196 °C, as follows: T1- Control: no cryoprotectants; T2- PVS2 (10 min), T3- PVS2 + phloroglucinol 1% (10 min), T4- PVS2 (10 min) + Supercool 1%; T5- PVS2 + phloroglucinol 1% (10 min) + Supercool 1%. Seed germination was evaluated after cryopreservation. The experimental design was completely randomized with five treatments and five replicates per treatment. Seed moisture at the beginning of the experiment was 6.2% for M. zehntneri and 7.8% for C. gounellei. There were no statistically significant differences for the seed germination percentage among the different treatments. Therefore, we concluded that seed of these two cacti species can be cryopreserved directly without the need for cryoprotectant solutions.