Aspectos da germinação e crescimento inicial de Genipa americana L. (Rubiaceae)

Abstract

Many efforts have been made to increase the diversity of tropical flora. These efforts are often hampered by limited knowledge of the basic biology of plant species. Genipa americana L. is a species that needs to be studied, because it is distributed throughout Brazil, it can develop in both dry and wetland areas, but is most commonly found in riparian forests, composed of secondary vegetation subject to temporary flooding . The germination of G. americana seeds from two populations of two municipalities (Dourados and Antônio João) was studied, subjecting them to different times and environments of submersion in water (laboratory and stream). In addition, the effect of lightness on initial growth and leaf anatomy of this species was evaluated. Seed submersion times in water were 0 (control), 16, 32, 64 and 128 days in laboratory and stream conditions. The shade levels in which the seedlings were submitted were 0, 30, 50 and 70%, evaluated up to 260 days of age. It was verified that the submersion of the seeds did not influence the germination, because this was superior to 80%, however, the growth of the seedlings from the submerged seeds was affected in the majority of the analyzed variables for the different populations and environments in which the seeds were submitted . For luminosity, it is possible to observe that G. americana seedlings showed a high survival rate at all shade levels, tolerating full sun and shade conditions to which they were exposed, but showed better growth in shaded environments. For the anatomy there was no difference between the treatments of shading and the leaves of this species presented common characters for the family Rubiaceae. It is concluded that G. americana is a species with phenotypic plasticity, because its seeds tolerate submersion in water and its seedlings tolerate several levels shading conditions.