Extended Abstract (144K)4A.2
Evidence for long-range transport of viable maize pollen
Yves Brunet, INRA, Bordeaux, France; and X. Foueillassar, A. Audran, D. Garrigou, and S. Dayau
Most experiments on the dispersal of maize pollen have been performed using ground-based systems with pollen traps located at various distances downwind from a source. Such measurements can only provide information on short-range dispersal in the surface boundary layer (i.e. within horizontal distances not exceeding a few hundred metres). In order to investigate whether longer-range transport may also occur, we study here the presence and viability of pollen throughout the atmospheric boundary layer (ABL). For this purpose a series of ten flights was performed with a light aircraft over a 4000 ha set of maize fields in South-West France, on several days with convective activity during the pollination period (July 2002 and 2003). Several flight legs were made at various altitudes between 150 m and 1800 m, i.e. within and above the ABL. A sampling device was built to collect pollen grains by impaction on Petri dishes located inside a plastic tube set up under the wing and facing forward. Pollen counts were made under a microscope after the flight was completed. Radio-soundings were collected in order to characterize the structure of the ABL. Pollen grains were found at all heights, with concentrations ranging from 0.2 (at the top) to 1.1 grains m-3 (at the bottom). The vertical variation in concentration was typical of the structure of the ABL on a convective day. The viability showed a smooth decrease with height but remained significant throughout the boundary layer. These results have profound implications on the possibility of long-range gene dissemination, because they show that in such climatic conditions viable pollen grains may travel over kilometres before they settle.
Session 4A, Aerial Movement and Dispersal of Spores, Pollens, Insects, Birds, and Other Aerobiota (parallel with session 4B)
Wednesday, 25 August 2004, 3:30 PM-4:30 PM
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