Chlorophyll Fluorescence of Plant Leaves as a Stress Indicator

The objective of the work is to determine the degree of plant stress detectable from fluorescence measurements. The experiments have been conducted with Pisum sativum and Hordeum vulgare grown in greenhouse conditions for 2–3 weeks. Plant stress in response to the application of Cd and Cu in different concentrations is quantified through changes in leaf pigment content. Heavy metals affect plant photosynthetic apparatus causing chlorophyll inhibition. Fluorescence spectra exited at 470 nm have been taken in the red and far-red spectral bands (640-800 nm). Significant increase of fluorescence emission of stressed plants in comparison to control plants has been observed across wavelengths from 678 to 765 nm. The experiments show that the heavy metal induced stress is detectable from fluorescence emission spectra revealing changes in fluorescence intensity and wavelength shifts which are associated with differences in plant chlorophyll content. The preliminary results of the study demonstrate that the analysis of fluorescence emission may timely and accurately indicate the onset of stress in plants.