Cryopreservation of Pyrostegia venusta (Ker Gawl.) Miers seeds

Abstract

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.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.