Relationships between flowering development of Ulmus pumila and Fraxinus excelsior and their airborne pollen.

LATORRE, F. & BIANCHI, M.M.

GRANA

Scandinavian University Press

Lugar: Sweden; Año: 1998 vol. 37 p. 233 - 238

0017-3134

ABSTRACT. RELATIONSHIPS BETWEEN FLOWERING DEVELOPMENT OF Ulmus pumila AND Fraxinus excelsior and their AIRBORNE POLLEN. The flowering patterns of Ulmus pumila and Fraxinus excelsior were studied during the 1990 growing season in order to investigate their pollen dispersion curves. The use of airborne pollen records as predictors of the flowering of allergenic trees was evaluated. A sampling method to describe quantitative flowering phenophases was applied. A Burkard trap recorded airborne pollen in the city of Mar del Plata. The phenological sampling method showed that floral phenophase development is not always synchronous between trees. The registered variability was larger for F. excelsior than for U. pumila. A delay between flowering and airborne pollen recorded was not noticed for Ulmus. The greatest Ulmus pollen amount came from local vegetation, mainly from U. pumila. Fraxinus pollen was recorded for a longer after the F. excelsior flowering season had ended. Fraxinus pollen income came from F. excelsior but also from F. americana and F. excelsior var. aurea that flower later. An immediate decrease in airborne concentration was noticed for both pollen types following rain. When relative strong rainfall was registered a decrease in the number of open flowers occurred only in F. excelsior.