Fluorescence characteristics of the diatom Cylindrotheca closterium (Ehrenberg) Reimann et Lewin, 1964

Abstract

Fluorescence characteristics of the diatom Cylindrotheca closterium previously adapted to light intensities of 17, 200, and 800 μE·m−2·s−1 were investigated. Possibility of using fluorescence parameters for express score of both the algae functional state and the identification of a range of optimal light intensities for their growth was shown. The variable fluorescence coefficient (Fv/Fm) allows to evaluate in express mode the algae functional state in intensive cultivation conditions. It was shown that the maximum of Fv/Fm was of 0.65–0.7 for algae grown at light intensities of 17 and 200 μE·m−2·s−1; it decreased to 0.48–0.57 for algae adapted to light intensities of 800 μE·m−2·s−1. Light response curves of the electron transport rate, photochemical and non-photochemical quenching of chlorophyll fluorescence, and the Fv’/Fm’ coefficient values were obtained. These parameters indicate the degree of algae resistance to the light factor level. It was shown that saturating light intensity of about 200 μE·m−2·s−1 is optimal for the growth of C. closterium. The high values of yield of fluorescence per chlorophyll unit under extreme light intensity (800 μE·m−2·s−1) may indicate the degree of inactivation of part of photosystem II reaction centers.