Estudo de germinação de Neptunia pubescens benth. (FABACEAE) no Bioma Pampa

Abstract

Grassland vegetation in the state of Rio Grande do Sul (RS) has undergone significant changes as a result of changes in land use, threatening countless species with extinction. Among the necessary actions for the preservation of endangered species, it is essential to investigate the most effective methods for their multiplication and propagation. This work aimed to understand the germination behavior of the endangered grassland angiosperm species, Neptunia pubescens Benth., comparing the effectiveness of some methods for overcoming dormancy. The seeds were collected from a specimen found in the city of São Gabriel - RS. The experiment was carried out in a greenhouse, with 50% shade and automatic daily irrigation at the Federal University of Pampa, São Gabriel campus. The treatments to break dormancy were mechanical scarification using sandpaper, thermal scarification, by immersion in water at 90ºC for five minutes, and the control treatment, without scarification. The germination speed index of the species (GSI), percentage of germination (G%) and amount of seeds germinated daily, as well as other complementary indices, were evaluated. Mechanical scarification promoted mean values of G=85% and GSI=9.5, which were significantly higher (P<0.05) than the results of the control treatment (G=3% and GSI=0.2), while scarification thermal (G=5% and GSI=0.5) did not differ from the control. Considering the indices analyzed in this study, it is concluded that the mechanical scarification method is effective in breaking dormancy in Neptunia pubescens seeds, promoting better germination than the control treatment, while thermal scarification did not differ significantly from the control.