Comparação da viabilidade de sementes de Schizolobium parahyba (Vell.) Blake - Leguminosae caesalpinioideae, pelos testes de germinação e tetrazólio

Abstract

Schizolobium parahyba (Vell.) Blake, known guapuruvu can be used in building, popular medicine and to forest restoration in riparian areas. There are little informations about its seed quality evaluation. The objectives of this work were to evaluate the temperature influence on seed germination and to test the tetrazolium salt efficiency to determine seed viability. Two seed lots were harvested in Machado's region - MG. To accelerate the germination process seed dormancy was broken with a cut in apical part and the pathogens incidence reduction was done by washing in sodium hipoclorite (2%). The seeds were sowed in poliethylen boxes (35x20x5cm) with sand as washed and sterilized at 120°C by 20 minutes as substrate. Seeds were maintained at constant temperatures 25°C, 30°C and 35°C with continuous light and at alternate temperatures 20°-30°C, with 8 hours of light. The evaluations were realized considering root emergence, normal seedlings and speed germination index. For tetrazolium test, after immersion of seeds were immersed 48 hours and to seed coats removal the embryos were kept in tetrazolium salt at 0,05% and 0,1%, at 30°C into a germination chamber (BOD) in dark by 5 hours. In the germination tests, the temperatures at 25°C and 35°C promoted higher germination percentage and speed germination index than the other temperatures. In the tetrazolium test the concentration 0,05% was better than 0,1% promoting a more efficient evaluation of seed viability of this species and all the classes obtained were efficient to evaluate the seed viability.