Fig. 9
Multivariate analysis (PCA) and contributions of the fluorescence and biometric variables to the system (A) and season (B). Centroid and 95% CI for each season are showed. Initial fluorescence (Fo – electrons.quantum−1), represents all oxidized quinone A; Variable fluorescence (Fv – electrons.quantum−1) indicates damage to the antenna complex caused by stress; Maximum fluorescence (Fm – electrons.quantum−1) represents all reduced quinone, the higher the better the energy dissipation in the electron transport chain. The quantum efficiency index of FSII or potential photosynthetic activity (maximum quantum production ratio of competing photochemical and non-photochemical processes in FSII (Fv/Fo ou kP/KN—electrons quantum−1), demonstrates that this parameter is related to the energy captured and the energy dissipated. The index (Fm/Fo) is the ratio between the maximum and initial fluorescence. PSII Quantum Efficiency, the lower the stress, the greater the stress, indicating damage to the photosynthetic apparatus (Fv/Fm). PhiPo or TRo/ABS or φPo is the maximum primary photochemical quantum yield index of PSII, non-photochemical dissipation of energy in the form of heat. PhiEo or ETo/ABS or φEo or PHI(Eo) is the index that demonstrates the probability of an exciton moving an electron through the electron transport chain after Quinone A (Qa). Psio is the probability, in time t = 0, of a trapped exciton moving an electron through the electron transport chain after Qa-. PiAbs or ψABS is the performance index based on absorption, reflects the efficiency of light absorption between capture and transfer of FSII excitation, representing the dissipation of photochemical energy through the formation of ATP and NADPH. ABS/RC is the energy absorption per reaction center, the growth in this index indicates an apparent increase in the photosystem's antenna complex to compensate for the high loss of energy as heat. PhiDo or φDo is the energy dissipation quantum yield. TRo/RC is the flow of energy trapped by reaction center. ETo/RC is the electron transport flow per reaction center. DIo/RC is the specific flow of energy dissipation per reaction center at the level of chlorophylls in the antenna complex, representing disorder at the beginning of the energy transport process. PhiPav or φPAV is the time to reach maximum chlorophyll fluorescence (ms)