Comparing the times that significant pollen concentrations were recorded to the
magnitudes of the rms values, Fig. 12 suggests that sw was at
least larger than 0.15–0.2ms1 (especially clear in Fig. 12b,
during the morning hours of 17 July) when pollen was
airborne. With the exception of 17 July, the magnitude of sw
drops to almost zero close to sunset, and no pollen were
captured by the Rotorods after sunset. On 17 July, after sunset,
sw remained relatively high and exceeded 0.15–0.2m s1 while
at the same time the relative humidity was well below 100%
(Fig. 10a), thereby setting the right conditions for anther
dehiscence and pollen emission/dispersal. However, also in
this case no airborne pollen was sampled. Apparently, the
corn anthers did not emit any pollen, raising questions as to
how anther maturation is linked to the diurnal solar cycle.