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The STUDIA UNIVERSITATIS BABEŞ-BOLYAI issue article summary
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Abstract: The 4000 µmol.m-2.s-1 light has decreased the excitation energy capture rate because of the closing of the reaction center, this fact being due to photoinhibition. Nonphotochemical dissipation of the energy is related to xanthophyll cycle activity. DCMU has maintained the plastoquinone reduction state at a high level, while the zeaxanthin has decreased. Sodium azide has inhibited the photochemical efficiency and quantum yield operating on the photosynthetic electrons mobility, leading to the inactivation of the xanthophyll cycle. Propyl gallate and salicylhydroxamic acid inhibit the photochemical efficiency and the quantum yield, and the light photochemical conversion was increased at the level of antenna together with the nonphotochemical dissipation of the excess energy. The xanthophyll cycle components were decreased together with the proteins decrease. In the presence of thenoyltrifluoroacetone and rotenone the closed QA acceptors have been enhanced, and the quanta conversion inside of antenna has enhanced activating the xanthophyll cycle, this leading to zeaxanthin enhancement. The dithiothreitol led to decrease of fluorescence, quanta conversion and excess energy dissipation. The xanthophyll cycle was inhibited. The Q-A favors the interactions between photosynthesis and chlororespiration while the presence of the inhibitors of mitochondrial respiration influences or stimulates the photosynthetic electrons transport.
KEYWORDS: chlorophyll fluorescence, excitation pressure, HPLC, quenching coefficients, violaxanthin de-epoxidase
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