Phaseolus vulgaris and ozone: results from open-top chamber experiments in France and England

Abstract

The response of Phaseolus vulgaris cv. ‘Lit’ to O 3 was investigated in open-top chamber (OTC) experiments at Sutton Bonington in the English East Midlands, and Pau in the south-west of France. At both sites, the crop was exposed in OTCs ventilated with charcoal-filtered air (Pau-CF and SB-CF treatments), non-filtered air (Pau-NF and SB-NF) or non-filtered air with added O 3 (Pau-NF20 and SB-NFL, -NFM, -NFH). In the Pau experiment, O 3 was added for 7 h day −1 and 7 days week −1, whereas in the Sutton Bonington experiment O 3 additions were for 7 h day −1, and 3–4 days week −1. The seasonal 7-h mean O 3 concentrations were 8, 39 and 58 nl l −1 in the Pau-CF, -NF and -NF20 treatments, respectively, and 8, 21, 27, 33 and 38 nl l −1 in the SB-CF, -NF, -NFL, -NFM and -NFH treatments, respectively. Bronze stippling, characteristics of chronic O 3 stress, appeared 21 days after emergence (DAE) in the Pau-NF20 treatment, and 60 DAE in the SB-NFH treatment. At the green harvest (61 and 66 DAE at Pau and Sutton Bonington, respectively) there was a 41% reduction in plant dry weight in the Pau-NF20 treatment (compared with the Pau-CF treatment) whereas there were no significant O 3 effects on dry weight in any of the Sutton Bonington treatments. By the dry harvest, the percentage effect of O 3 on seed yield was linearly related to the seasonal 7-h mean O 3 concentration. The results from both experiments fitted into the same relationship even though there were differences in the O 3 exposure regime, physical and pollution climates and soil characteristics at Sutton Bonington and Pau.