Influence of incompatible pollen grains on the reproductive success of Ipomoea asarifolia (Desr.) Roem. & Schult. (Convolvulaceae) in Restinga, RN, Brazil

The deposition of incompatible pollen grains in the stigma can interfere with the performance of compatible pollen grains and compromise the reproductive success of the species in the community. Ipomoea asarifolia, a self-incompatible species, occurs in sympathy with I. brasiliana, sharing pollinators, but without hybrid formation. However, this condition favors the deposition of auto pollen and interspecific pollen in the stigma, which can compromise the reproductive success of the species in the community. Given this, we investigated the influence of incompatible intra- and interspecific pollen grains on their reproductive success of I. asarifolia, based on analyses of natural pollination and controlled experiments. Our hypothesis is that the presence of incompatible pollen grains in the stigma negatively interferes with the formation of fruits and seeds in I. asarifolia. Fruit yield was significantly higher in manual cross-pollination than in natural pollination and mixed pollination experiments of compatible (intraspecific: cross-pollinated pollen) and incompatible (intraspecific: self-pollen and interspecific: pollen of I. brasiliana) pollens. Seed yield was significantly higher in cross-pollination than between the two mixed pollination experiments. Seed production was not significantly different between cross-pollination and natural pollination, nor between natural pollination and mixed pollination experiments. However, fruit and seed production was higher in cross-pollination than in other situations. And experiments with incompatible amounts of pollens do not form fruits. Few fruits and seeds are formed in the presence of incompatible pollens (intra and interspecific), which may be interfering with reproductive success in I. asarifolia, especially in the long term. We reinforce the importance of the selection of reproductive displacement in the species to minimize the flow of incompatible pollens and their reproductive interferences.