PSII photochemistry in vegetative buds and needles of Norway spruce (Picea abies L. Karst.) probed by OJIP chlorophyll a fluorescence measurement

Katanić, Zorana and Atić, Lejla and Ferhatović, Dž. and Cesar, Vera and Lepeduš, H. (2012) PSII photochemistry in vegetative buds and needles of Norway spruce (Picea abies L. Karst.) probed by OJIP chlorophyll a fluorescence measurement. Acta Biologica Hungarica, 63 (2). pp. 218-230. ISSN 0236-5383

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Abstract

Vegetative buds represent developmental stage of Norway spruce (Picea abies L. Karst.) needles where chloroplast biogenesis and photosynthetic activity begin. We used the analyses of polyphasic chlorophyll a fluorescence rise (OJIP) to compare photosystem II (PSII) functioning in vegetative buds and fully photosynthetically active mature current-year needles. Considerably decreased performance index (PI_ABS) in vegetative buds compared to needles pointed to their low photosynthetic efficiency. Maximum quantum yield of PSII (F_v/F_m) in buds was slightly decreased but above limited value for functionality indicating that primary photochemistry of PSII is not holdback of vegetative buds photosynthetic activity. The most significant difference observed between investigated developmental stages was accumulation of reduced primary quinine acceptor of PSII (Q_A⁻) in vegetative buds, as a result of its limited re-oxidation by passing electrons to secondary quinone acceptor, Q_B. We suggest that reduced electron transfer from Q_A⁻ to Q_B could be the major limiting factor of photosynthesis in vegetative buds.

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