The growth and development of Vicia faba L. in filtered and unfiltered open‐top chambers

SUMMARY The response of Vicia faba cv. Ticol to ambient levels of air pollutants was investigated using open-top chambers (OTCs) ventilated with ambient air (NF treatments) and charcoal-filtered air (CF treatments). The OTCs were placed over a conventionally drilled crop shortly after emergence in April 1988, and remained in place until after the crop was harvested in September 1988. The daily mean pollutant concentrations were 15, 7, 6 and 9 nl 1−1 for O3, SO2, NO and NO2 respectively inside NF OTCs, and 6, 3, 8 and 5 nl I−1 respectively for CF OTCs. These pollutant levels were accompanied by changes in both the vegetative and the reproductive development of V. faba. The upper leaves of plants growing in CF air expanded to larger areas than corresponding leaves on NF plants, and the canopy of CF plants intercepted more radiation than that of NF plants. At flowering, CF plants had 11 % more flowers than NF plants. This difference was maintained during early pod development and was caused by greater retention of pods on the upper racemes of CF plants. As the pods dried however, more pods were abscised from CF plants than from NF plants, and by harvest the number of pods per plant was comparable for the two treatments. Thus the observed differences in growth and development were transient and did not result in differences in final yield.