Study onPlatanus hispanica Miller pollen content in the air of Seville, southern Spain

The work was carried out using a Cour trap that sampled the air of the city for 8 consecutive years (1987–1994). The pollen ofPlatanus hispanica is the fourth most abundant in the air of Seville (a mean of 11.05% of the total pollen collected). The variation throughout the years in the sum of weekly concentrations ofPlatanus hispanica pollen presents a certain biennial rhythm, in which years of high and low collection of pollen alternate. The starting day of the main pollination period (MPP) is negatively related with the mean of the mean temperatures for February (r=0.73,r ²=0.53,P=0.0398) and is earlier (at the beginning of March) when the mean temperature for February is high, and vice versa. The pattern of pollen variation inPlatanus hispanica remains constant through the years—pollen appears abruptly in high weekly concentrations (> 150 grains/m³) in March (sporadically at the beginning of April), with a week of maximum pollen emission (WMPE) in which more than 50% of the annual pollen is collected (in 6 of the 8 years), and a main pollination period (MPP) of 2 or 3 weeks (except in 1989 when it was 5 weeks). In every year (except 1989), weekly mean temperatures increased during the MPP, the duration of which depends on mean temperature and mean rainfall: mean temperatures > 16°C and absence of rainfall shorten the MPP, while lower temperatures and presence of rainfall lengthen it. The meteorological conditions most often found during the WMPE are mean temperatures > 15°C and rainfall absent or almost so.