above a pollinating corn field were measured
during 10 days together with relevant meteorological and
turbulence parameters. Pollen concentrations decreased
rapidly with elevation, e.g. at twice the canopy height they
were reduced to about 30% of those observed at canopy height.
Diurnal cycles of atmospheric pollen concentration were
characterized by an initial emission of pollen after sunrise,
with peak values during the morning hours and decaying
values during the afternoons. No significant pollen concentrations
were measured starting 2 h before sunset until the
following morning at sunrise. Presumably the diurnal solar
cycle is intimately tied to anther maturation which ultimately
governs pollen emission.