Resumo Sementes de Pyrostegia venusta (Ker Gawl.) Miers) foram dessecadas a 25 °C, sobre sílica gel por 0 h (T0), 7 h (T1) e 24 h (T2), atingindo teores de água de 6,5%, 4,4% e 3,8%, respectivamente. As sementes foram congeladas em nitrogênio líquido (+NL), a -263 ºC.min.-1 e após 72 h foi descongeladas à temperatura ambiente de 25 ± 2 ºC, a 5 °C.min.-1. A avaliação da germinabilidade das sementes antes (-NL) e após congelamento (+NL) foi conduzida a 25 °C, substrato rolo de papel, fotoperíodo 16 h luz/8 h escuro e contagens de plântulas normais por 38 dias. Os percentuais germinativos foram de 88% (T0-NL), 98% (T0+NL), 61% (T1-NL), 95% (T1+NL), 78% (T2- NL) e de 89% (T2+NL). Os tempos médios para a formação de plântulas foram de 23 (T0-NL), 22 (T1-NL e T2-NL) e de 30 dias para as sementes expostas ao NL. O congelamento rápido, o descongelamento lento e os três teores de água testados foram adequados para a criopreservação de sementes de Pyrostegia venusta.
Abstract Seeds of Pyrostegia venusta (Ker Gawl.) Miers) were desiccated at 25 °C on silica gel for 0 h (T0), 7 h (T1) and 24 h (T2), reaching moisture contents of 6.5%, 4.4% and 3.8%, respectively. Seeds were frozen rapidly in liquid nitrogen (+LN) at -263 °C.min.-1 and after 72 h, they were thawed slowly at room temperature (25 ± 2 °C) at a speed of 5 °C.min.-1. Seed germinability evaluation before (-LN) and after freezing (+LN) was conducted at 25 °C, on paper roll substrate, and germinated at 16 hrs light/8 hrs dark, normal seedling counts for 38 days. The germinative percentages were 88% (T0-LN), 98% (T0+LN), 61% (T1-LN), 95% (T1+LN), 78% (T2-LN) and 89% (T2+LN). Mean days for seedling formation were 23 (T0-LN), 22 (T1-LN and T2-LN) and 30 days for seeds exposed to LN. Fast freezing, slow thawing, and the three tested moisture contents, were suitable for cryopreservation of Pyrostegia venusta seeds.