Seeds germination of Senna siamea (Lam.) H.S. Irwin e Barneby - Caesalpinoideae

Abstract

enna siamea is a tree from Thailand that has adapted well to the climatic conditions of the Northeast of Brazil, that has been used for arborization, hedges and timber production. This research was divided in two experiments that aimed to identify methods to break dormancy and verify how temperature and light can affect germination of its seeds. In the experiment the germination percentages of hard and dead S. siamea seeds were determined using the treatments: humid heat, immersion in sulfuric acid and hot water, mechanical scarification, aiming at breaking dormancy and the control. In the second experiment, S. siamea seeds that had been immersed in sulfuric acid were placed on filter paper and submitted to five light period/temperature combinations: continuous light and constant temperature (25°C), continuous light and two different temperatures (35°C/8h and 20°C/16h), continuous dark and constant temperature (25°C), continuous dark and two different temperatures (35°C/8h and 20°C/16h), and different light periods and temperatures (light/35°C/8h and dark/20°C/16h). From the experiments it was concluded that S. siamea seeds present dormancy. The best treatments for breaking dormancy were mechanical scarification and sulfuric acid. The seeds were indifferent to the light and their germination was not influenced by the tested temperatures.