Biologia floral e produtividade de grãos de três híbridos de girassol (helianthus annuus l.) Em função do comportamento de pastejo e eficiência polinizadora da abelha apis mellifera.

Abstract

The research was carried out in the counties of Russas (Campo Federal) and Fortaleza (Universidade Federal do Ceará), both in the state of Ceara, Brazil, from August 2005 to January 2006. Floral biology and seed productivity of three sunflower (Helianthus annuus) hibrids, H250, H251 e H360, and foraging behavior and pollination efficiency of the honey bee (Apis mellifera) were investigated. One hectare of each hybrid was planted in Russas, with an interval of 40 days to avoid coincidence of flowering between one or more hibrid, aiming to collect data on seed productivity, foraging behavior and pollination efficiency of the honey bee. Data on the hibrid’s floral biology were obtained in Fortaleza, from two 5 x 10 m areas planted with the three hybrids. The analyses of data were carried out by ANOVA, means were compared a posteriori by Tukey test (5%) and, in the cases where interactions were found, by regression analyses. Results showed that the three hibrids tested have similar floral biology for the parameters studied, differing only in corolla depth, though not affecting their attractiveness to Apis mellifera foragers; that honey bees forage throughout the day in flowers of the three hybrids, concentrating nectar harvesting in the morning shift and pollen collection in the afternoon; that seed productivity obtained was higher than the Brazilian average seed productivity and equivalent to the World’s one. It was concluded that Apis mellifera was efficient in pollinating the three hibrids studied in this research, but there is a need of deeper investigations on the pollination of these hibrids to explain the high seed productivity observed from inflorescences protected against flower visitors.