CHLOROPHYLL-A FLUORESCENCE AND CHLOROPHYLL CONTENT IN PARMELIA-QUERCINA THALLI FROM A POLLUTED REGION OF NORTHERN CASTELLON (SPAIN)

Measurements of modulated chlorophyll a fluorescence emission and chlo rophyll content were made in thalli of Parmelia quercina collected fro m northern Castellon (Spain). Although high air pollution concentratio ns have been measured in this area, the ratio of variable to maximal f luorescence is unaffected. Following dark-adaptation, the response to irradiance of chlorophyll fluorescence was examined. With respect to c ontrol samples, thalli collected in northern Castellon consistently sh owed differences in fluorescence quenching, the efficiency of excitati on energy capture and quenching of basal fluorescence. However, the qu antum yield of photochemistry and non-cyclic electron flow were not af fected. The changes in chlorophyll fluorescence parameters were observ ed in the absence of both visual injuries and decrease in chlorophyll content. The results are discussed with regard to the possible role of environmental stress in chlorophyll fluorescence yield. (C) 1996 The British Lichen Society