Leaf level detection of steady state fluorescence and PRI for early ozone injury assessments

The research activities are addressed to find optical signals of the oxidative stress linked to ozone exposure of plants. The connection of ozone damage to remote sensing (RS) is motivated by the interest in developing a rapid and non-intrusive way of evaluation of plant physiological status (ground level RS) and by the appealing possibility of monitoring large areas (airborne and satellite RS). Excess energy dissipation pathways (heat and fluorescence) were monitored as indicators of plant physiological status with field spectroscopy techniques on poplar clones subjected to ozone fumigation at leaf level. Xantophyll-related heat dissipation was estimated through the Physiological Reflectance Index (PRI) calculated from a traditional field spectrometer and steady-state fluorescence under natural illumination conditions was estimated by exploiting the Fraunhofer Line-Depth principle and spectrally modeling the radiance collected with very high resolution spectrometers (FWHM=0.13 nm). Preliminary results of the ozone fumigation experiment are presented.