Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia L.), a known allergy-inducing species: implications for public health.

Abstract

Although environmental factors such as precipitation and temperature are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide concentration ([CO₂]) on the potential growth and pollen production of hay-fever-inducing plants is unknown. Here we present measurements of growth and pollen production of common ragweed (Ambrosia artemisiifolia L.) from pre-industrial [CO₂] (280 mol mol^–1) to current concentrations (370 mol mol^–1) to a projected 21st century concentration (600 mol mol^–1). We found that exposure to current and elevated [CO₂] increased ragweed pollen production by 131 and 320%, respectively, compared to plants grown at pre-industrial [CO₂]. The observed stimulations of pollen production from the pre-industrial [CO₂] were due to an increase in the number (at 370 mol mol^–1) and number and size (at 600 mol mol^–1) of floral spikes. Overall, floral weight as a percentage of total plant weight decreased (from 21% to 13%), while investment in pollen increased (from 3.6 to 6%) between 280 and 600 mol mol^–1 CO₂. Our results suggest that the continuing increase in atmospheric [CO₂] could directly influence public health by stimulating the growth and pollen production of allergy-inducing species such as ragweed.