Contenu pollinique de l’atmosphère de la ville de Cotonou (Bénin) : cas des plantes ornementales

Abstract

Aim of the studyThe present study consists in analyzing the pollen content of the atmosphere at three sites (Akpakpa, Cadjèhoun, and Vêdoko) of the city of Cotonou (Benin) to know the quantitative and qualitative composition of pollens. MethodPollens were trapped on a microscopic slide coated with silicone oil under the SLT sensor. The direct field observation method was used to identify flowering species from November 2019 to November 2020. ResultsIn total 19,921 pollen grains were counted. Ornamental plants pollens represent 28.23% against 71.76% for non-ornamental plants, and dominant in the air during rainy seasons. More than 50% of the species were always in flower, but the months from August to November 2020 are richer in flowering. The pollen spectrum showed that: Pithecellobium dulce, Acacia auriculiformis, Terminalia mantaly, Euphorbia milii, Celosia cristata, Acalypha wilkesiana, and Casuarina equisetifolia are the most common ornamental species in the atmosphere of Cotonou. ConclusionThe rainy and short dry seasons are the peak flowering periods for ornamental species in Cotonou City. Their pollen abundance in the atmosphere is low compared with non-ornamental species. As for temperature, it has a significant influence on pollen dispersal: when it rises, so does the number of pollens in the air.