Effect of Desiccation Time on Seed Moisture and Regeneration of Mangaba (Hancornia speciosa) Embryos

Hancornia speciosa Gomes, popularly known as mangaba tree, is a fruit tree native to Brazil, with natural occurrence in several regions. However, some factors have contributed to the reduction of natural populations of this species, in addition to the recalcitrant characteristic of its seeds, which hinders their storage for conservation purposes. The application of plant tissue culture techniques is a complementary strategy to the conservation of the existing genetic variability and allows accelerating the multiplication of promising genotypes. This study aimed to evaluate the effect of the desiccation time of mangaba tree on seed moisture and regeneration using cryopreserved and non-cryopreserved embryos. Seeds were extracted from mature and immature fruits of BRA00074140-5 accession, belonging to Mangaba Tree Active Germplasm Bank of Embrapa Tabuleiros Costeiros, Sergipe, Brazil. At 24 hours after seeds extraction, they were desiccated in Magenta ™ boxes containing silica gel (50 g/magenta) for 0, 8, 10, 12, and 14 hours, at room temperature. Seed moisture (four samples of five seeds/maturation) was determined for each desiccation period. After each desiccation period, seeds were inoculated in germination medium (control 2), and two samples of ten seeds for each desiccation time were immediately placed in cryotubes and immersed in liquid nitrogen (-196ºC). For the evaluation of the germination percentage, seeds were thawed in sucrose solution for 24 hours. Subsequently, embryos were excised and inoculated in MS culture medium with 3% sucrose and 0.30% Phytagel® and evaluated at 60 days of culture. Cryopreserved seeds regenerated no embryos. Further studies should be performed to obtain regeneration from cryopreserved seeds.