CHLOROPHYLL FLUORESCENCE, AND NITROGEN AND PIGMENT CONTENT OF SCOTS PINE (PINUS-SYLVESTRIS) NEEDLES IN POLLUTED URBAN HABITATS

Chlorophyll fluorescence induction was measured under field conditions on Scots pine (Pinus sylvestris L.) needles in seven stands in the City of Helsinki. The contents of chlorophylls a and b, total carotenoids and total nitrogen were determined, as well. At three sites, the F(V)/F(M) ratio of chlorophyll fluorescence induction was exceptionally low (<0.8), indicating reduced quantum yield of photosystem II. The chlorophyll, carotenoid and nitrogen contents of the needles were highest at the same three sites. The nitrogen content correlated positively with the chlorophyll and carotenoid contents and negatively with F(V)/F(M). Oxides of nitrogen (NO(X)) and traffic emissions are discussed as possible factors affecting the light reactions of photosynthesis and the pigment content of pine needles in an urban environment. Measurement of chlorophyll fluorescence under field conditions seems to be a suitable method for the detection of damage caused by air pollutants.