ISHS Acta Horticulturae 561: VIII International Symposium on Pollination - Pollination: Integrator of Crops and Native Plant Systems
DYNAMIC DISPENSING OF POLLEN: AN EMPIRICAL STUDY |
| Author: | A.V. Etcheverry |
| Keywords: | Crotalaria micans; male function; pollen dispersal; pollen removal; sexual strategies |
| Abstract:
Pollen dispensing mechanisms have been considered as a prevalent force in floral evolution, acting mainly through three floral characters: nectar production; poricidal anthers; and, secondary pollen presentation. Such mechanisms enhance pollen dispersal by restricting pollen removal by individual bees during a series of visits (dispensing schedule). Recently, a theoretical model has predicted that plants which execute a dynamic adjustment of pollen removal to the frequency of visits allow optimal pollen dispersal (i.e., when visitors are frequent the proportion of pollen removed is smaller than when they are rare). Up to now, empirical support for this model is only available for Lupinus sericeus (Fabaceae: Papilionoideae). However, dynamic dispensing could be a common character of pollen removal from plants with secondary pollen presentation. I studied the effect of inter-visit interval on pollen removal in Crotalaria micans Link (Fabaceae: Papilionoideae), a species which presents its pollen secondarily in a stigmatic brush, in response to the pressure applied by bees to wings and keel. Pollen removal from C. micans flowers, expressed as proportion of remaining pollen removed, varied directly with manipulation interval. Over all manipulations, the mean removal proportion for 5 min intervals was significantly lower than the mean proportion removed after 20 and 40 min intervals, but there was no difference between 20 and 40 min intervals. I concluded that long intervals between visits led to greater pollen removal from C. micans flowers than do short intervals, as was observed in Lupinus sericeus. | |
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