Is low fruiting success linked to sexual expression in Acacia caven?

CALVIÑO A.; ASHWORTH L.; MOYETTA, N.

FLORA

ELSEVIER GMBH

Año: 2014

0367-2530

Abstract In long-lived plants, sexual expression is often highly variable in time and space. The extent to which sexual dimorphism of flowers is expressed in the same or in separate individuals, may have implications for the plants´ dependence on pollen vectors, the quality of the pollen received, and the potential for setting fruits under distinct pollination environments. Here, we account for sexual expression variability in the small tree Acacia caven, which produces hermaphrodite and male flowers in the same or in separate individuals. We focus on whether individual sexual expression influences fruit set, which has been reported as being extremely low in this species. Individual sexual expression, estimated as the hermaphrodite:male flowers ratio was variable both between and within plants in two reproductive seasons. Though male flower production could be very high (up to 99% of the flowers), all trees produced both flower types within the same individual, thus confirming andromonoecy in this species. More interestingly, hermaphrodite:male flowers ratio had a negative effect on fruit set. This pattern was consistent in the two reproductive seasons and suggests that maleness should favor female function. Similar trends found in other plant species with the same sexual system support the hypothesis that male flowers of andromonoecious species should contribute to reduce self-pollen interference compared with hermaphrodite flowers. By increasing pollen quality and fruit set, maleness would then help to maintain andromonoecy in this and other andromonoecious species.