Biologia reprodutiva de Mauritia Flexuosa L.(ARECACEAE) em vereda no município de Uberlândia – MG

Abstract

Mauritiaflexuosa is a dioecious palm tree, typical of flooded areas and, in the region of Savanna, it is restricted to palm swamp. Data on its reproductive biology in this vegetation are scarce. The objectives of this work were to study the flowering and ffuctification phenology, the reproductive biology and identify the visitors of M. flexuosa. The study was accomplished in an area of palm swamp located in the Park of Sabiá (18° 57'S and 48°14'W), in Uberlândia, State of Minas Gerais, in the period ffom September 1999 to June 2001. In order to obtain data of the phenologycal events, 71 individuais were marked and accompanied each fifteen days. To analyze aspects of the flower morphology, time of anthesis, production of odour type, resources, longevity, receptivity of the stigma and viability of pollen five staminate individuais and five pistillate ones, were evaluated. Pistillate inflorescences were bagged to evaluate the apomixis occurrence. Focal observations were accomplished in several individual of both sexes to determine the visitors ffequency and their behavior in the flower. The flowering was annual during the study period that extended ffom November to April with a peak in March 2000, and in April 2001. The maturation of the fruit takes more than one year. The beginning of ripening fruits occurred in the following year after the blooming during May and June. The size of the inflorescences varied ffom 2.5 - 4m both for the staminate and the pistillate ones. The number of flowers for pistillate inflorescence was of 3,576.3 ± 167.4 (n=5) and in the staminate ones it was of 204,747 ± 2,992.5 (n=3). There were 5.4 ± 1.8 (n=31) inflorescences on the average in the pistillate plants, and 5.3 ± 1.7 (n = 19) in the staminate ones in the first year of flowering. In the second year the average was of 2.4 ± 1.5 of pistillate inflorescences and 2.5 ± 1.3 of staminate inflorescences. The opening of the pistillate and staminate flowers occurs along the day with a peak around 6 p.m. The flowers possess orange color with soft and sweetened odour. Only the pistillate flower produces néctar, with médium volume of 2.5 jxl ± 0.9 (n = 120) and the average of sugar concentration of 19.5% ± 6.2 (n=10). The stigmatic receptivity happens between the 4th and 5th day, after the anthesis and the pistillate flower lasts about eight days. The staminate flower lasts only 1-2 days. It doesn't happen apomixis in this species. The found visitors were coleoptera (Nitiduüdae, Mycetophagidae and Curculionidae), which were restricted to the staminate flowers, and hymenoptera and diptera that visited the flowers of both sexes. In the area of study, Trigona sp (Meliponini: Apidae) was considered as the main pollinator.