Germinação de sementes de guabirobeira sob diferentes intensidades luminosas

Abstract

The family of Myrtaceas comprehend a mean of 3500 species, having as an important species of this family the Campomanesia xanthocarpa Berg, an arboreal species, native to Brazil. This species is found from Minas Gerais to Rio Grande do Sul and is popularly known as “guabiroba”, it has a big potential in the recovery of degraded areas and also for the diversification of production in family farming properties. Considering that factors as water, luminosity, temperature and edaphic conditions can affect the development of vegetation and that the lack or reduction in one of these factors can be limiting in the recovery of vegetation, the aim with this study was to evaluate the germination capacity of the “guabirobeira” seeds under different luminous intensities. The experiment was conducted in BOD, in the plant and tissue propagation laboratory of the Federal University of Fronteira Sul, Campus Chapecó, Santa Catarina, from November 2016 to January 2017. The experiment was composed of five treatments and eight replicates, with fifty seeds each, in a complete randomized design. The treatments were: T1 (full light, without gerbox cover); T2 (gerbox covered with shade cloth with 30% of light reduction); T3 (gerbox covered with shade cloth with 50% of light reduction); T4 (gerbox covered with shade cloth with 70% of light reduction); T5 (total cover of gerbox with aluminum foil). The variables analyzed were: percentage of germinated seeds in each count (every three days), total percentage of germinated seeds, percentage of ungerminated seeds that were classified as either hard, dormant or dead and speed of germination index (SGI). The data were submitted to the analysis of variance and, when significant, the means of the treatments were compared using the Tukey’s HSD test. The data expressed in percentage (germination) were transformed taking the roof of the arcsine of x/100. The different luminous intensities interfered in the germination of “guabirobeira” seeds, having the point of maximum efficiency in germination, for the treatments 0%, 30%, 50%, 70% e 100% of light reduction, in the 39th, 36th, 35th, 36th e 38th days, respectively, demonstrating that the treatments with 30%, 50% e 70% of light reduction presented a fester germination. For the germination rate, the treatment with 30% of light reduction presented greater germination, differing itself only from the treatment with total gerbox cover (T%). A similar result was verified for the SGI, as to the greater result, where the plants that presented greater germination, also presented themselves, with 50% of light reduction, the greatest SGI. In relation to the rate of hard, dormant and dead seeds, no hard seeds were observed in the experiment and there was no significant difference for the percentage of dead seeds. In relation to the dormant seeds, differences between the treatments were observed, considering that the treatment with total gerbox cover (T5) presented the greatest rate of dormant seeds. These results indicate that in clearing conditions or closed forest the “guabirobeira’s” seeds, possibly, will present lower germination indices, which can be a limiting factor to their propagation