Biologia floral de Dipteryx odorata (Aubl.) Willd. (Fabaceae).

Abstract

Studies on floral biology are part of the basic knowledge of tropical ecosystems, proving to be important for the management and conservation of natural resources. Dipteryx odorata (Aubl.) Willd. (Fabaceae), is a species of wood, medicinal and aromatic importance, due to the presence of coumarin, an essential oil found in seeds. The objective of this work was to study the floral biology of D. odorata in a planted area (Embrapa Amazônia Oriental - PA) and in a natural area (Tapajós National Forest - PA) investigating factors limiting fruiting, such as the attack of insect larvae in the flower buds, preventing the development of flowers and, consequently, the formation of fruits. The research was carried out in the period 2002/2003. Studies were carried out on: floral morphology, anthesis period, stigma receptivity, nectar production, fragrance production, pollen / egg ratio, phenology, floral visitors, pollination tests, larvae attacks, germination and pollen tube growth. The species presents papilionaceous hermaphrodite flowers, white and pink in color, arranged in terminal erect paniculate inflorescences, with morning anthesis, which exude a strong sweet odor. These butterflies and hummingbirds. However, they have attributes that fit them in the melitophilia syndrome. The period of greatest visitation coincides with the period of greatest concentration of sugars in the nectar, during the morning. Flowering is asynchronous and cornucopia, lasting an average of three to four weeks, occurring between September and December. The fruiting occurred from October to July and the spread between the months of May to July. With the results obtained through the pollen / egg ratio and pollination tests, this species fits into the reproductive system of mandatory xenogamy, being a self-sterile species, with the self-incompatibility index (ISI) = 0.03. The effectiveness of natural pollination, obtained through the reproductive efficiency index (RE), was 0.14. However, the presence of a late self-incompatibility system was observed, which prevents the full development and maturation of the fruits resulting from induced self-pollination. These fruits are aborted, on average, in the first five weeks after the beginning of fruit development. In the flower buds and flowers, larvae of coleoptera are found, which caused serious damage to the flowers and the consequent formation of fruits. In the planted area, the level of infestation was 9.54%. There was a difference in pollen germination for the different treatments and periods collected, in the tests of open pollination and induced self-pollination the germination started only with 72h. In the pistils used for cross-pollination, pollen germination was observed after 48 h. The reduction in the production of ripe fruits in relation to the initiated fruits may be being regulated by the occurrence of abortion, availability and service of the pollinators and the damage caused by the attack of larvae on the flowers, contributing to the reduction of formed fruits.