Estrutura do pericarpo e análise de frutos abortados e predados de Syagrus glaucescens Becc. (Arecaceae) in situ e ex situ

Abstract

Syagrus glaucescens is an endangered and endemic palm of the campos rupestres of Serra do Espinhaço, Minas Gerais, Brazil, aspects that make conservation of the species of high importance. Two conservation methods are commonly applied, ex situ and in situ, both equally important for the protection of this palm and other endangered species. The high production of reproductive structures is typical of the Arecaceae family, but most of the flowers and fruits produced are lost by natural abortion or predation, phenomena previously observed in S. glaucescens, which makes the investigation of these processes very interesting. This work evaluated the occurrence of abortion and predation processes in populations of S. glaucescens from the morphological, anatomical and ontogenetic points of view. We also verify if there is difference between fruits involved in these processes and those resulting from the normal development in the studied species, comparing natural population (in situ) with a cultivated one (ex situ). Conventional techniques of plant anatomy (fixation, dehydration, sectioning and staining) were used, as well as counts and measurements that were statistically analyzed. The structure of the ovary and the normal fruit development of S. glaucescens showed typical characteristics of the Arecaceae, such as the presence of peripheral fiber blocks and the formation of the pyrene by the activity of the subadaxial meristem; the fruits also presented evident emergencies on the outer surface. The aborted and predated fruits showed anatomical differences in their tissues comparing to the fruits with normal development. Especially, alteration was observed in the amount of phenolic compounds in aborted fruits and in the pyrene formation. Predated fruits also exhibited changes in the pyrene, in addition to changes in the parenchyma cells of the inner mesocarp and in the formation of emergencies. Flower production ex situ was significantly higher than in situ. There was no significant difference in fruit abortion between the two sampled areas and fruit predation was only marginally significant. There was, however, a significant difference in abortion and fruit predation among individuals in each evaluated area.