Indicators of ozone effects on Fagus sylvatica L. by means of spectroradiometric measurements

In this paper optical indices calculated from leaf reflectance measurements, acquired with a high resolution spectroradiometer, were investigated to monitor Ostress on Fagus sylvatica L. from the strain phase to the damage phase when visible symptoms occur (e.g. chlorosis, leaf browning). The CI (Chlorophyll Index) was the most sensible index to a wide range of chlorophyll (Chl) concentrations (R 2 =0.93), the simple ratio R 695 /R 740 (Ctr2) was the most correlated to carotenoids/chlorophyll (Car/Chl) ratio (R 2 =0.65), while YI (Yellowness Index) was sensible to Car/Chl ratio and to low Chl values but tends to saturate at moderate to high Chl concentrations. PRI (Photochemical Reflectance Index ) was correlated with the physiological parameters NPQ (Non Photochemical Quenching) and ∆F/ ' Fm confirming this index is a good indicator of photosynthetic efficiency. Results from this experiment showed that CI, Ctr2 and PRI were reliable indices of O � effects on Fagus sylvatica L. before visible symptoms occurred, while YI was able to detect the senescence anticipation when visible symptoms already spread. These results were confirmed by physiological parameters measured in field (F v /F m, NPQ and / ' F Fm D ).

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