Photosynthetica - Ahead of Print
In honor of Hartmut Karl Lichtenthaler
G. GOVINDJEE
Photosynthetica X:X | DOI: 10.32615/ps.2020.080 
We honor here Hartmut Karl Lichtenthaler, a pioneer of plant physiology, plant biochemistry, plant biophysics, plant molecular biology, and stress physiology. His contributions to the ingenious use of chlorophyll a fluorescence imaging in understanding the physiological processes in leaves stand out. We wish him many happy and productive years of research and educating others.
Can chlorophyll fluorescence imaging make the invisible visible?
R. VALCKE
Photosynthetica X:X | DOI: 10.32615/ps.2021.017
Chlorophyll fluorescence has developed into a well-established noninvasive technique to study photosynthesis and by extension, the physiology of plants and algae. The versatility of the fluorescence analysis has been improved significantly due to advancements in the technology of light sources, detectors, and data handling. This allowed the development of an instrumention that is effective, easy to handle, and affordable. Several of these techniques rely on point measurements. However, the response of plants to environmental stresses is heterogeneous, both spatially and temporally. Beside the nonimaging systems, low- and high-resolution imaging systems...
Multi-colour fluorescence imaging of photosynthetic activity and plant stress
H.K. LICHTENTHALER
Photosynthetica X:X | DOI: 10.32615/ps.2021.020
Imaging the four fluorescence bands of leaves, the red (F690) and far-red (F740) chlorophyll (Chl) fluorescence as well as the blue (F440) and green (F520) fluorescence of leaves and the corresponding fluorescence ratios is a fast and excellent nondestructive technique to detect the photosynthetic activity and capacity of leaves, of gradients over the leaf area as well as the effect of various strain and stress parameters on plants. This review primarily deals with the first and pioneering multi-colour fluorescence imaging results obtained since the mid-1990s in a cooperation with French colleagues in Strasbourg...
The love-hate relationship between chlorophyll a and water in PSII affects fluorescence products
C.R. GUADAGNO, D.P. BEVERLY, B.E. EWERS
Photosynthetica X:X | DOI: 10.32615/ps.2021.023
Chlorophyll a (Chl a) has an asymmetrical molecular organization, which dictates its orientation and the location of the pigment in the mature photosynthetic apparatus. Although Chl a fluorescence (ChlF) is widely accepted as a proxy for plant photosynthetic performance under countless stress conditions and across species, a mechanistic understanding of this causality is missing. Since water plays a much greater role than solvent for the photosynthetic machinery, elucidating its influence on Chl a may explain the reliable reflection of plant stress response in the ChlF signal. We examine the effect of hydration from well-watered...
A comparison of chlorophyll fluorescence transient measurements, using Handy PEA and FluorPen fluorometers
B. PADHI, G. CHAUHAN, D. KANDOI, A. STIRBET, B.C. TRIPATHY, G. GOVINDJEE
Photosynthetica X:X | DOI: 10.32615/ps.2021.026
We provide here a general introduction on chlorophyll (Chl) a fluorescence, then we present our measurements on fast (< 1 s) induction curves (the so-called OJIP transients) on dark-adapted intact leaves of Arabidopsis thaliana, under five different light intensities [in the range of ~ 500 to ~ 3,000 µmol(photons) m‒2 s‒1] using two different instruments: Handy PEA (Hansatech Instruments, UK; excitation light, 650 nm) and FluorPen (model FP-110; Photon Systems Instruments, The Czech Republic; excitation light, 470 nm). We then discuss the observed differences...