Screening of bean cultivars for their response to ozone as evaluated by visible symptoms and leaf chlorophyll fluorescence

Fourteen Italian cultivars of Phaseolus vulgaris were exposed to a single p ulse of ozone (O-3, 150 nl l(-1)) or to filtered air (< 3 nl l(-1)) for 3.5 h. O-3 sensitivity was assessed by recording the extent of visible symptom s, effects on chlorophyll (Chl) content and changes in Chl a fluorescence p arameters. This paper reports the results of an initial screening of 14 bea n cultivars that was used to select a small number of cultivars for further work. Seven cultivars showed visible symptoms of injury in the range of 2- 60 h after the end of the O-3 fumigation. O-3 significantly depressed total Chi content in most cultivars and a significant correlation was found betw een Chi content and visible symptoms. Most cultivars showed a significant c hange in the F-v/F-m ratio, even when there were no visual symptoms. There was no relationship between the extent of visual symptoms and quenching coe fficients, indicating that these parameters were of no use in the determina tion of sensitivity to O-3 stress. (C) 2000 Elsevier Science Ltd. All right s reserved.