METHODS FOR OVERCOMING DORMANCY OF QUIXABEIRA SEEDS ( Sideroxylon obtusifolium (Roem.& Schult.) T.D.Penn.)

Abstract

Devido \ue0 aus\ueancia de informa\ue7\uf5es sobre a metodologia para avalia\ue7\ue3o da qualidade fisiol\uf3gica de sementes das esp\ue9cies arb\uf3reas medicinais, o presente trabalho teve por objetivo determinar o m\ue9todo mais eficiente para supera\ue7\ue3o da dorm\ueancia tegumentar em sementes de Sideroxylon obtusifolium (Roem. & Schult.) T.D.Penn.. Al\ue9m das sementes intactas, sementes que n\ue3o foram submetidas a nenhum tratamento, tamb\ue9m foram utilizados os seguintes tratamentos pr\ue9-germinativos: escarifica\ue7\ue3o qu\uedmica - as sementes foram imersas em \ue1cido sulf\ufarico absoluto por 10, 20, 30, 40, 50 e 60 minutos; escarifica\ue7\ue3o mec\ue2nica - as sementes foram friccionadas manualmente em lixa n\ub0 50, do lado oposto \ue0 micr\uf3pila, sem ou com embebi\ue7\ue3o por 24 ou 48 horas; imers\ue3o em \ue1gua a 100\ub0C por 15 ou 30 segundos; imers\ue3o em \ue1gua a 80\ub0C at\ue9 o resfriamento. Os efeitos foram avaliados atrav\ue9s de testes de germina\ue7\ue3o e vigor. Constatou-se que houve diferen\ue7a significativa entre os tratamentos para todos os par\ue2metros avaliados (porcentagem e velocidade de germina\ue7\ue3o, comprimento e massa seca de parte a\ue9rea e raiz prim\ue1ria), e a causa mais evidente da dorm\ueancia \ue9 a impermeabilidade do tegumento, a qual foi superada com maior efici\ueancia pelo m\ue9todo de imers\ue3o em \ue1cido sulf\ufarico por 30 minutos.Due to absence of information about the methodology for the evaluation of the physiological quality of seeds of medicinal arboreal species seeds, the aim of the present work was to determine the most efficient method to overcome the seed coat dormancy in seeds of Sideroxylon obtusifolium (Roem.& Schult.) T.D.Penn.. Besides the intact seeds, the ones which had not been submitted to any treatment, the following pre-germinating methods were used: chemical scarification: the seeds were immersed in pure sulfuric acid for 10, 20, 30, 40, 50 and 60 minutes at the environment temperature (27\ub0C \ub1 1\ub0C); mechanical scarification: the seeds were rubbed manually in sandpaper number 50, in the opposite side of micropyle, without and with soaking for 24 or 48 hours; thermal scarification: immersion in water at 100\ub0C for 15 or 30 seconds; immersion in water to 80\ub0C until cooling. The effects of treatments were evaluated through tests of germination and vigor. There were significant differences among the treatments for all the evaluated parameters (percentage and speed of germination, length and dry weight of shoot and root), and the most evident cause of dormancy was the coat impermeability, which efficiency was overcame by the immersion of seeds in pure sulfuric acid for 30 minutes