Chlorophyll fluorescence imaging of photosynthetic activity with the flash-lamp fluorescence imaging system

Abstract

A flash-lamp chlorophyll (Chl) fluorescence imaging system (FL-FIS) is described that allows to screen and image the photosynthetic activity of several thousand leaf points (pixels) of intact leaves in a non-destructive way within a few seconds. This includes also the registration of several thousand leaf point images of the four natural fluorescence bands of plants in the blue (440 nm) and green (520 nm) regions as well as the red (near 690 nm) and far-red (near 740 nm) Chl fluorescence. The latest components of this Karlsruhe FL-FIS are presented as well as its advantage as compared to the classical single leaf point measurements where only the fluorescence information of one leaf point is sensed per each measurement. Moreover, using the conventional He-Ne-laser induced two-wavelengths Chl fluorometer LITWaF, we demonstrated that the photosynthetic activity of leaves can be determined measuring the Chl fluorescence decrease ratio, R Fd (defined as Chl fluorescence decrease F d from maximum to steady state fluorescence F s : F d /F s ), that is determined by the Chl fluorescence induction kinetics (Kautsky effect). The height of the values of the Chl fluorescence decrease ratio R Fd is linearly correlated to the net photosynthetic CO 2 fixation rate P N as is indicated here for sun and shade leaves of various trees that considerably differ in their P N . Imaging the R Fd -ratio of intact leaves permitted the detection of considerable gradients in photosynthetic capacity across the leaf area as well as the spatial heterogeneity and patchiness of photosynthetic quantum conversion within the control leaf and the stressed plants. The higher photosynthetic capacity of sun versus shade leaves was screened by Chl fluorescence imaging. Profile analysis of fluoresence signals (along a line across the leaf area) and histograms (the signal frequency distribution of the fluorescence information of all measured leaf pixels) of Chl fluorescence yield and Chl fluorescence ratios allow, with a high statistical significance, the quantification of the differences in photosynthetic activity between various areas of the leaf as well as between control leaves and water stressed leaves. The progressive uptake and transfer of the herbicide diuron via the petiole into the leaf of an intact plant and the concomitant loss of photosynthetic quantum conversion was followed with high precision by imaging the increase of the red Chl fluorescence F 690 . Differences in the availability and absorption of soil nitrogen of crop plants can be documented via this flash-lamp fluorescence imaging technique by imaging the blue/red ratio image F 440 /F 690 , whereas differences in Chl content are detected by collecting images of the fluorescence ratio red/far-red, F 690 /F 740 .Additional key words: blue-green fluorescence; chlorophyll fluorescence decrease ratio; diuron absorption; flash light pulses; nitrogen supply; R Fd -ratio; sun and shade leaves, water stress.

Investigation of Leaf Diseases and Estimation of Chlorophyll Concentration in Seven Barley Varieties Using Fluorescence and Hyperspectral Indices

“…Several studies have consistently shown that RF/FRF is a good inverse indicator of the chlorophyll content [10,18,61]. However, our results show that BF/FRF (BFRR_UV) yielded the highest correlation with LCC (Figure 5c), suggesting that the BF/FRF (BFRR_UV) can serve as an indicator of the leaf chlorophyll.…”

Application of photochemical parameters and several indices based on phenotypical traits to assess intraspecific variation of oat (Avena sativa L.) tolerance to drought

“…Chlorophyll a fluorescence kinetics (CF) allows determining whether the photosynthetic apparatus was damaged after cessation of watering. Fluorescence methods have been successfully applied in many studies related to plant drought resistance (Lichtenthaler and Babani 2004;Lichtenthaler et al 2005;Hura et al 2007;Rapacz et al 2010);Yin et al 2010). CF-modulated parameters are commonly used in the JIP-test.…”

Comparative response on the accumulation of inorganic phosphate in leaf of Basella alba to low and high temperature

“…Therefore, the availability of inorganic phosphate plays a significant role for acclimation to such adverse conditions. High temperature stress directly or indirectly affects plant photosynthetic functions by changing the structural organization and physico-chemical properties of thylakoid membranes (Lichtenthaler et al 2005). The rate of photorespiration increases with increasing temperature which reduces net photosynthesis and probably the seed yield of the crop.…”