How to correctly determine the different chlorophyll fluorescence parameters and the chlorophyll fluorescence decrease ratio R_Fd of leaves with the PAM fluorometer

• DOI: 10.1007/s11099-005-0062-6
• Publication Date: 2005-10-07T08:39:19Z
• Authors: H. K. Lichtenthaler; C. Buschmann; M. Knapp
• Keywords: Fluorometer; Quantum yield

This contribution is a practical guide to the measurement of different chlorophyll (Chl) fluorescence parameters and gives examples their development under high-irradiance stress. From Chl induction kinetics upon irradiation dark-adapted leaves, measured with PAM fluorometer, various parameters, ratios, quenching coefficients can be determined, which provide information on functionality photosystem 2 (PS2) photosynthetic apparatus. These are Fv, Fm, F0, Fm', Fv', NF, ΔF, ratios Fv/Fm, Fv/F0, ΔF/Fm', as well photochemical (qP) non-photochemical (qN, qCN, NPQ). qN consists three components (qN = qE + qT qI), determined via relaxation in dark period after kinetics. The above many state primarily PS2. In fully developed green dark-green leaves these at upper adaxial leaf side, only reflect small portion chloroplasts palisade parenchyma cells outer half. Thus, fluorometer measurements have performed both sides obtain all whole leaf. Combined high irradiance (HI) heat stress, applied strongly reduced quantum yield energy conversion half nearly zero, whereas signals lower side were not or little affected. During this HL-stress treatment, qN, NPQ increased sides, but much higher extent compared side. was best indicator for even during stronger HL-stress, qCN decreased progressive stress though still continued. It recommended determine, addition classical also decrease ratio RFd (Fd/Fs), which, when saturation directly correlated net CO2 assimilation rate (PN) leaves. RFd-ratio from using continuous saturating light (cSL) 4-5 min. As RFd-values fast measurable indicators correlating activity they should always parallel other ratios.