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

Abstract

This contribution is a practical guide to the measurement of the different chlorophyll (Chl) fluorescence parameters and gives examples of their development under high-irradiance stress. From the Chl fluorescence induction kinetics upon irradiation of dark-adapted leaves, measured with the PAM fluorometer, various Chl fluorescence parameters, ratios, and quenching coefficients can be determined, which provide information on the functionality of the photosystem 2 (PS2) and the photosynthetic apparatus. These are the parameters F v , F m , F 0 , F m ', F v ', NF, and ∆F, the Chl fluorescence ratios F v /F m , F v /F 0 , ∆F/F m ', as well as the photochemical (q P ) and non-photochemical quenching coefficients (q N , q CN , and NPQ). q N consists of three components (q N = q E + q T + q I ), the contribution of which can be determined via Chl fluorescence relaxation kinetics measured in the dark period after the induction kinetics. The above Chl fluorescence parameters and ratios, many of which are measured in the dark-adapted state of leaves, primarily provide information on the functionality of PS2. In fully developed green and dark-green leaves these Chl fluorescence parameters, measured at the upper adaxial leaf side, only reflect the Chl fluorescence of a small portion of the leaf chloroplasts of the green palisade parenchyma cells at the upper outer leaf half. Thus, PAM fluorometer measurements have to be performed at both leaf sides to obtain information on all chloroplasts of the whole leaf. Combined high irradiance (HI) and heat stress, applied at the upper leaf side, strongly reduced the quantum yield of the photochemical energy conversion at the upper leaf half to nearly zero, whereas the Chl fluorescence signals measured at the lower leaf side were not or only little affected. During this HL-stress treatment, q N , q CN , and NPQ increased in both leaf sides, but to a much higher extent at the lower compared to the upper leaf side. q N was the best indicator for non-photochemical quenching even during a stronger HL-stress, whereas q CN and NPQ decreased with progressive stress even though non-photochemical quenching still continued. It is strongly recommended to determine, in addition to the classical fluorescence parameters, via the PAM fluorometer also the Chl fluorescence decrease ratio R Fd (F d /F s ), which, when measured at saturation irradiance is directly correlated to the net CO 2 assimilation rate (P N ) of leaves. This R Fd -ratio can be determined from the Chl fluorescence induction kinetics measured with the PAM fluorometer using continuous saturating light (cSL) during 4-5 min. As the R Fd -values are fast measurable indicators correlating with the photosynthetic activity of whole leaves, they should always be determined via the PAM fluorometer parallel to the other Chl fluorescence coefficients and ratios.

The Impact of Cadmium on Photosynthetic Performance and Secondary Metabolites in the Lichens Parmelia sulcata, Flavoparmelia caperata and Evernia prunastri

“…It has been found that prolonged exposure to lead (Pb) leads to an additional decrease of F v /F m in Flavoparmelia caperata (Garty 2002). In our study, we also employed a fl uorescence decrease ratio (R Fd ), a parameter which, when measured at saturation irradiance is directly correlated to the net CO 2 assimilation rate (Lichtenthaler et al 2005). The R Fd values in control lichens were mostly similar to R Fd values found in lichen Anaptychia ciliaris (Valladares et al 1995).…”

“…Maximum quantum yield of PSII (F v /F m ), a widely used indicator of photosynthetic effi ciency of photosystem II, was calculated as (F m -F 0 )/F m (Maxwell and Johnson 2000). Additionally, the fl uorescence decrease ratio (R Fd ), a parameter directly related to the rate of photosynthesis (Lichtenthaler et al 2005), was calculated as (F m -F s )/F s , according to Lichtenthaler et al (2005).…”

Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation

“…4b), similar to recovery responses of C0 2 assimilation and F v /F m in leaves of grapevine (Vitis vinifera L.) that were exposed to full sunlight following growth in the greenhouse under low UV irradiance and PAR (Kolb et al, 2001). Decreased F v /F m ratios recorded at the adaxial leaf side indicate photoinhibition occurring predominantly in the upper chloroplast layers (Lichtenthaler et al, 2005), which might be partly responsible for the differences between the response of F w IF m and A max . Calculated q/c a ratios indicated that the decrease in A max did not result from increased stomatal limitation of C0 2 uptake.…”

Short-term growth of meadow fescue with atmospheric CO2 enrichment decreases freezing tolerance, modifies photosynthetic apparatus performance and changes the expression of some genes during cold acclimation

“…Photosystem II antenna trapping efficiency was calculated as F v 0 /F m 0 . The chlorophyll fluorescence decrease ratio (vitality index) was calculated in accordance with Lichtenthaler et al (2004) as…”