Effect of Technogenic Hydrocarbons on Chlorophyll a Variable Fluorescence Parameters in Leaves of Seedlings of Deciduous Plants

Abstract

Effects of technogenic hydrocarbons (benzоpyrene, butyl acetate and o-xylene) on the state of stress-sensitive photosystem II in the leaves of drooping birch seedlings, small-leaved linden, maple holly and poplar pyramidal were assessed by pulse-amplitude modulated fluorimetry (РАМ). The degree of response to toxication, though being similar for toxic agents of different nature, depended on the previous stress in plants. Indeed, birch seedlings that had undergone natural stress reacted weaker to chemical one. The leaves of poplar showed the highest response to toxicity combined with rapid adaptability. The most sensitive parameter was the coefficient of non-photochemical fluorescence quenching qN, which increased after treatment with hydrocarbons by 2-5 times in seedlings of different species. The nonradiative dissipation of excitation energy is probably the main mechanism for protecting photosynthetic membranes under chemical stress.