Effects of sub-optimal illumination in plants. Comprehensive chlorophyll fluorescence analysis.
The fluorescence signals emitted by chlorophyll molecules of plants is a promising non-destructive indicator of plant physiology due to its close link to photosynthesis. In this work, a deep photophysical study of chlorophyll fluorescence was provided, to assess the sub-optimal illumination effects on three plant species: L. sativa, A. hybridus and S. dendroideum. In all the cases, low light (LL) treatment induced an increase in pigment content. Fluorescence ratios - corrected by light reabsorption processes - remained constant, which suggested that photosystems stoichiometry was conserved. For all species and treatments, quantum yields of photophysical decay remained around 0.2, which meant that the maximum possible photosynthesis efficiency was about 0.8. L. sativa (C3) acclimated to low light illumination, displayed a strong increase in the LHC size and a net decrease in the photosynthetic efficiency. A. hybridus (C4) was not appreciably stressed by the low light availability whereas S. dendroideum (CAM), decreased its antenna and augmented the quantum yield of primary photochemistry. A novel approach to describe NPQ relaxation kinetics was also presented here and used to calculate typical deactivation times and amplitudes for NPQ components. LL acclimated L. sativa presented a much larger deactivation time for its state-transition-related quenching than the other species. Comprehensive fluorescence analysis allowed a deep study of the changes in the light-dependent reactions of photosynthesis upon low light illumination treatment.
['Torres|R|R|', 'Romero|J M|JM|', 'Lagorio|M G|MG|']
D027721:Amaranthus D002734:Chlorophyll D005456:Fluorescent Dyes D007700:Kinetics D018545:Lettuce D008029:Lighting D055668:Photochemical Processes D010788:Photosynthesis D010936:Plant Extracts D018515:Plant Leaves D031963:Sedum
Chlorophyll fluorescence Photosynthesis NPQ components Kautsky kinetics Non-photochemical quenching OJIP PSII Variable fluorescence Xanthophyll cycle