Ecologia da germinação e potencial para formação de banco desementes de espécies de Arthrocereus A. Berger (Cactaceae)endêmicas dos campos rupestres de Minas Gerais, Brasil

Abstract

(Germination ecology and seed bank of Arthrocereus A. Berger (Cactaceae)endemic species of rupestrian fields of Minas Gerais, Brazil). Fruits and seeds biometry, theinfluence of light and temperature in germinative behavior, and longevity of seeds stored insitu and in laboratory were evaluated for four taxa of Arthrocereus. Germination experimentswere conducted at six constant temperatures, under 12 hours photoperiod and undercontinuous dark. The in situ storage was carried out in the soil, at the place of naturaloccurrence of species, and evaluation was done every two months until 14 months. Seed weredry stored in laboratory, at room temperature, for 12 months. The results indicate that,although the variation found between the four studied taxa, there is a pattern in thegerminative behavior. Seeds are small, with absolute requirement of light to germinate. In thepresence of light, there were high germination percentages between 20 and 30 °C and lowgermination at a 10, 15 e 35 °C. This behavior may represent a mechanism of escape whenthe environmental conditions in rupestrian fields are not favorable for seedlings survival. Ingeneral, the germination was relatively slow, which possibly favors the occurrence ofgermination in the rain period. The dry storage did not significantly alter the seed germinationbehavior. Seeds stored in the soil remained viable, showing high germination until the lastevaluation. Thus, we can infer that seeds of the species studied are able to form persistentseed bank.