Effects of nitrogen dioxide pollution on the growth of three fern species

The effects of exposing plants of Dryopteris filix-mas (L.) Schott, Phyllitis scolopendrium (L.) Newman and Polypodium vulgare L. to 60 nl litre −1 (122 μg m −3 ) NO 2 for 37 weeks were investigated in a closed chamber fumigation system. There was no effect of NO 2 on the numbers of fronds produced for any species at any time during the exposure period. However, at the end of the study, there was a lower dry weight yield of green shoots of D. filix-mas and P. scolopendrium and a higher yield of green shoots of P. vulgare for plants in the NO 2 treatment as compared to control plants. These differences in shoot dry weights were not accompanied by an effect of NO 2 exposure on total plant dry weights.