Long-distance pollen flow in large fragmented landscapes
Résumé
Recent evidence has shown that maize pollen can travel and remain viable at regional scales, which opens the possibility for long-distance cross-pollination. Here, we first report results obtained on small plots of white-kernel maize used as pollen traps, in a region with extensive maize cultivation, demonstrating that cross-pollination can indeed occur at several kilometres from the nearest source field. We also used the atmospheric Meso-NH model to better understand long-range dispersal of maize pollen. Simulations were performed over Southwest France during the maize pollination period. When compared with airborne measurements, the model provides good estimates of pollen concentration throughout the atmospheric boundary layer. It allows the pollen plume to be characterized during the day and permits the production of deposition maps of accumulated viable pollen. These results quantify long-distance pollen deposition; they show that background levels of cross-pollination are unavoidable at the regional scale and support the use of low purity thresholds by supply chain operators.