Biologia Reprodutiva da Palmeira Licuri (Syagrus coronata) (Mart.) Becc. (Arecaceae) na Ecorregião do Raso da Catarina, Bahia

Abstract

The necessity of deeper knowledge of the biology of a vegetable species, mainly about the reproductive biology, is very important for appropriate management. Syagrus coronata (Mart.) Becc. is a palm known as licuri, which has a very high social and ecological importance mainly in the Northeastern semi-arid region of Brazil, because of its importance for the feeding of wildlife, mainly the rare Lear’s macaw. However, it is in a situation of population decline which requests for studies on the reproductive system with the purpose of comprehension of the reproductive process and success of the species. This research contains two complementary studies about Syagrus coronata, the first one is about the morphometry of the reproductive structures and the second is about the floral and reproductive biology; both of them were carried out in an area located in the municipality of Paulo Afonso/BA. Forty adult individuals were selected and identified in a natural licuri palm population. For the study of the morphometric description of the reproductive structures, monthly visits were made during March to December of 2008, with the purpose of collecting and verifying the development of reproductive structures of ten different individuals. It was observedthat Syagrus coronata has interfoliar spadix; peduncular inflorescence panicle type with 66,9 (± 13,8) rachillas, which bear a total of 11.741,8 (± 3.392,6) yellow flowers, with 10.915,9 (± 3.115,4) staminate flowers and 825,9 (± 501,9) pistillate flowers. It presents an accentuated protandry (about ten days). The infruitescence presents 333,4 (± 185,2) fruits (drupe), with an ellipsoid and brown pyrene. To the study the floral and reproductive biology of S. coronata, the reproductive system and the pollination and dispersion syndromes were characterized. Through the determination of the P/O ratio and pollen viability, and by making controlled pollination experiments, tests were made to verify the occurrence of self pollination, anemophily and agamospermy in 30 different individuals. Floral visitors andpossible seed dispersers were also identified. The P/O ratio of inflorescence is 1,76 106 (± 0,12) and the mean pollen viability obtained from floral bud is 96,9% (± 0,74). Although it is self-compatible, there is a high tendency of cross-pollination, due to the existence of accentuated dichogamy (protandry). The formation of apomitic fruits was not verified. It was observed that entomophily is responsible for 67,2%, while the wind pollination is responsible for 32,8% of the pollination of flowers. The main floral visitors in the inflorescences and flowers were the bees Trigona spinipes and Apis mellifera (Apideae) and the beetle Microstrates ypsilon (Curculionideae). T. spinipes is the main pollinator agent. The seed dispersal is strictly zoochoric, thus could act as disperser agents the birds Anodorhynchus leari and Penelope sp. and the mammals Dasyprocta sp., Thrichomys sp. and Tayassu sp., as well as, species of cattle from the genus Bos sp., Capra sp. and Ovinis sp. in disturbed areas subject to the pasturage. Due to its strategies, floral reward, high pollen viability and very high pollen-ovule ratio, as well as, the formation of fruits in the experiments in cross-pollination and in self pollination, in addition to the occasional synchrony between female and male phases in different inflorescences in the same individual, lead to the conclusion that this species is facultativelyxenogamous. It is hoped that this study can help to subsidize population enrichment projects and to enlarge the possibilities of sustainable management of this native species.