Evaluation of the photosynthetic characteristics of upland cotton (Gossypium hirsutum L.) germplasm based on chlorophyll a fluorescence

Y. SUN, X.M. XU, Y.H. JIA, W.Q. DONG, X.M. DU, H.Q. DENG, C.M. TANG

Photosynthetica 2021, 59(4):693-701 | DOI: 10.32615/ps.2021.043  

Handy Plant Efficiency Analyser (Handy PEA) provides a method for the high-throughput screening of photosynthetic germplasm. However, the large number of chlorophyll a fluorescence parameters (CFPs) from PEA and the inconsistency of CFP applications among studies greatly limit the accuracy of photosynthesis analyses. In this study, all 53 CFPs of 186 upland cotton cultivars (strains) were measured at 12:00 and 17:00 h. Thirty-two CFPs were selected according to biological importance, and the CFP relationships were determined. Differences in the response ability of cotton cultivars (strains) to high light intensity stress were demonstrated...

The melatonin receptor CAND2 is involved in the regulation of photosynthesis and chloroplast gene expression in Arabidopsis thaliana under photooxidative stress

I.A. BYCHKOV, N.V. KUDRYAKOVA, E.S. POJIDAEVA, V.V. KUSNETSOV

Photosynthetica 2021, 59(4):683-692 | DOI: 10.32615/ps.2021.061  

Melatonin is a well-known bioactive molecule able to mitigate photooxidative damage caused by excess light. Here we have shown that mutant Arabidopsis lines with disrupted genes for melatonin putative receptor CAND2/PMTR1 and GPA1 encoding the α-subunit of heterotrimeric G-protein were partially insensitive to melatonin treatment under high light stress. They exhibited a higher degree of photodamage due to a significantly decreased photosynthetic activity and diminished expression of chloroplast and nuclear-encoded genes and the corresponding proteins. A possible mechanism for melatonin-dependent regulation of chloroplast...

Crop responses and management strategies under shade and drought stress

I. SHAFIQ, S. HUSSAIN, B. HASSAN, A. RAZA, I. AHMAD, M.A. ASGHAR, Z. WANG, T. TAN, S. LI, X. TAN, A. GHAFOOR, A. MANAF, M. ANSAR, F. YANG, W. YANG

Photosynthetica 2021, 59(4):664-682 | DOI: 10.32615/ps.2021.057  

The occurrence of shade and drought stress either individually or simultaneously causes altered morphophysiological and molecular responses in crops. Nevertheless, responses of crop plants to combined shade and drought stress are unique as compared to those of individually occurring stress which urges need to study and identify distinctions, commonalities, and the interaction between responses of plants to these concurrent stress factors. In the present review, we outlined currently available knowledge on responses of plants to shade and drought stress on a shared as well as the unique basis and tried to find a common thread potentially underlying...

Zinc and cadmium as modulating factors of the morphophysiological responses of Alternanthera tenella Colla (Amaranthaceae) under in vitro conditions

E. CLAIRVIL, J.P.R. MARTINS, P.C.S. BRAGA, S.W. MOREIRA, L.T. CONDE, R. CIPRIANO, A.R. FALQUETO, A.B.P.L. GONTIJO

Photosynthetica 2021, 59(4):652-663 | DOI: 10.32615/ps.2021.059  

Zinc (Zn) plays an important role in the physiological processes in plants and may mitigate trace element stress. The aim was to evaluate the morphophysiological responses of Alternanthera tenella plants exposed to cadmium (Cd) and Zn under in vitro conditions. Segments of A. tenella were transferred to flasks containing medium supplemented with different combinations of Cd (0, 75, or 150 μM) and Zn (0, 750, or 1,500 μM) concentrations, totalizing nine treatments. We assessed the growth traits, anatomy, chlorophyll a fluorescence by OJIPs, and tolerance index (TI). With exposure only to Cd, the plants showed physiological...

Response of physiological characteristics and grain yield of winter wheat varieties to long-term heat stress at anthesis

C.H. GAO, M. SUN, S. ANWAR, B. FENG, A.X. REN, W. LIN, Z.Q. GAO

Photosynthetica 2021, 59(4):640-651 | DOI: 10.32615/ps.2021.060  

Heat stress has become more common in recent years, limiting wheat production in Huang-Huai-Hai plain in China. To identify the effect of long-term heat stress on wheat production, two heat-resistant (JM44, JM23) and two heat-sensitive (XM26, GC8901) wheat varieties were sown in heat tents and normal conditions, and heat stress (9 to 12℃ higher than control) was imposed for seven days at post-anthesis. All varieties under heat stress exhibited early senescence and reduced grain-filling rate, while the grain-filling period of heat-tolerant varieties was longer than that of the heat-sensitive. Furthermore, long-term heat stress significantly reduced...

Fatty acid composition and cpDNA content in Arabidopsis thaliana mutants deprived of EGY1 protease

M. ADAMIEC, M. SZOMEK, E. GABAŁA, J. DOBROGOJSKI, L. MISZTAL, R. LUCIŃSKI

Photosynthetica 2021, 59(4):633-639 | DOI: 10.32615/ps.2021.053  

EGY1 (ethylene-dependent gravitropism-deficient and yellow-green 1) is an intramembrane metalloprotease located in chloroplasts, involved in many diverse processes including chloroplast development, chlorophyll biosynthesis, and the ethylene-dependent gravitropic response. Plants deprived of this protease display pleiotropic effects such as the yellow-green early senescence phenotype and a poorly developed thylakoid system membrane in the mature chloroplasts. We applied the GC/MS technique to analyze the changes in fatty acid composition in two egy1 mutant lines. We used DAPI staining and transmission electron microscopy methods to establish...

Effects of red to far-red light ratio on growth and photosynthetic characteristics of tomato seedlings under calcium nitrate stress

X.T. ZHOU, Z.L. LI, J.J. HE, X.Y. WANG, Q.L. LIU, J. HUANG, Y.D. XIE, Z.Q. HE

Photosynthetica 2021, 59(4):625-632 | DOI: 10.32615/ps.2021.052  

Secondary soil salinization causes plant stress, which can be relieved by different ratios of red to far-red light (R:FR). Our study aimed to elucidate the role of low R:FR ratios treatments on photosynthesis and growth of tomato seedlings in salinized soils. Tomato seedlings were treated under three R:FR ratios and calcium nitrate was applied simultaneously. The results showed that the treatments under low R:FR ratios stimulated growth parameters of tomato seedlings under calcium nitrate stress, the best impact being achieved at the R:FR ratio of 0.7 in this experiment. Low R:FR ratios treatments increased proline content as well as PSII maximum efficiency,...

Mitochondrial alternative oxidase pathway acts as an electron sink during photosynthetic induction in Rumex K-1 leaves

D.D. CHENG, L.T. ZHANG

Photosynthetica 2021, 59(4):615-624 | DOI: 10.32615/ps.2021.047  

Chloroplast PSII photochemical efficiency is upregulated more rapidly than CO₂ assimilation during photosynthesis induction, suggesting the existence of other electron sinks than that of CO₂ assimilation. We hypothesized that the mitochondrial alternative oxidase (AOX) pathway could be such a sink. Inhibition of the AOX restricted light activation of the malate-oxaloacetate shuttle and caused an excessive reduction of PSI acceptor side and substantial accumulation of Q_A^-, hindering the photosynthetic linear electron transport rate (ETR) and leading to an imbalance between light energy absorption and exploitation...

James Barber (1940-2020): A very remarkable biochemist of our time

G. GOVINDJEE

Photosynthetica 2021, 59(4):606-614 | DOI: 10.32615/ps.2021.058  

Photoprotective roles of ascorbate and cstyleZostera marinacstyle

W. ZHAO, Q.S. ZHANG, Y. TAN, Z. LIU, M.Y. MA, M.X. WANG, C.Y. LUO

Photosynthetica 2021, 59(4):600-605 | DOI: 10.32615/ps.2021.051  

The oxygen-evolving complex (OEC) of Zostera marina is prone to deactivation under visible light, which results in a formation of the long-lived radical P₆₈₀⁺. The mechanism to prevent damage caused by P₆₈₀⁺ remains unclear. In this study, following light exposure, the upregulation in ascorbate (AsA) content and the presence of PSII cyclic electron flow (PSII-CEF) provide evidence that AsA and PSII-CEF donate electrons to PSII. Furthermore, a factorial design experiment with different combinations of inhibition of AsA and PSII-CEF demonstrates that both inhibition treatments lead to decreases in maximal...

The moderating role of population succession in the adaptive responses of Synechococcus assemblages: evidence from light intensity simulation experiment

T. WANG, X. CHEN, J.L. LI, S. QIN, Y.L. CUI, F. XU

Photosynthetica 2021, 59(4):587-599 | DOI: 10.32615/ps.2021.050  

Synechococcus is one of the most abundant photoautotrophic picoplankton in the marine ecosystem. However, it is not clear how Synechococcus assemblages respond to light intensity variation in a genus group. Here, enriched Synechococcus assemblages from in situ coastal seawater were subjected to light intensity simulation experiments in a range of 9-243 μmol(photon) m^-2 s^-1. Characteristics concerning physiology, genomics, and metatranscriptomics were analyzed. Physiologically, the fitting model predicted photosynthesis indications and pigment contents increased with different trends following the light...

Insights into nanoparticle-induced changes in plant photosynthesis

M. GHORBANPOUR, A. MOVAHEDI, M. HATAMI, K. KARIMAN, F. BOVAND, M.A. SHAHID

Photosynthetica 2021, 59(4):570-586 | DOI: 10.32615/ps.2021.049  

Photosynthesis can be affected by nanoparticles (NPs) both negatively (e.g., through decreasing the chlorophyll content and electron transport rate, damages to chloroplast components, etc.) or positively (e.g., via enhancing chlorophyll content, the activity of Rubisco enzyme, the performance of PSII, and CO₂ harvesting, as well as broadening the chloroplast photoabsorption spectrum). Enhanced photosynthetic efficiency could be a possible impact of NPs on photosynthetic organisms of major economic and ecological significance (e.g., crops and algae), which warrants an in-depth understanding of NPs interactions...

Photosynthetic traits and biochemical responses in strawberry (Fragaria × ananassa Duch.) leaves supplemented with LED lights

G. LAURIA, E. LO PICCOLO, E. PELLEGRINI, E. BELLINI, T. GIORDANI, L. GUIDI, G. LORENZINI, F. MALORGIO, R. MASSAI, C. NALI, L. PAOLI, D. REMORINI, L. SANITA' DI TOPPI, P. VERNIERI, M. LANDI

Photosynthetica 2021, 59(4):557-569 | DOI: 10.32615/ps.2021.048  

Selected light wavebands promote plant development and/or the biosynthesis of targeted metabolites. This work offers new insights on the effects of red (R), green (G), blue (B), and white (W - R:G:B; 1:1:1) LED light supplementation on physiochemical traits of strawberry leaves. Gas exchange and chlorophyll fluorescence parameters, photosynthetic pigments, and superoxide anion (^*O₂^-) content were analysed in plants grown for 1 (T1) and 17 (T17) d with light supplementations. At T1, light supplementations resulted in the enhancement of the de-epoxidation state of xanthophylls and nonphotochemical quenching, but no changes...

Blue light dosage affects photosynthesis, chlorophyll, and antioxidant properties of Mesembryanthemum crystallinum

H. ZHANG, Y. TU, J. KANG, W. SONG, L. ZHENG

Photosynthetica 2021, 59(4):547-556 | DOI: 10.32615/ps.2021.046  

Mesembryanthemum crystallinum is an annual succulent plant that is being used as an emerging healthy leafy vegetable. To investigate the growth and physiological response of M. crystallinum to artificial lighting, five different light treatments were applied at 150 µmol(photon) m^-2 s^-1, which were white (W), different rations of red/blue (B) (15, 40, and 70%B), and blue (100%B), respectively. Our results showed that plants could gain as much as edible leaf area and dry mass with a certain ratio of blue (40%) in comparison with W. Plants grown under 100%B resulted in reduced photosynthetic rate, leaf area, and fresh...

Effects of temperature and nitrogen application on photosynthetic characteristics and the absorption and distribution of carbon and nitrogen in apple plants

H.H. ZHANG, H.F. LIU, Z. LI, H.F. DING, Z.X. XUE, F.Y. ZHAO, S.L. YU, K. YU

Photosynthetica 2021, 59(4):538-546 | DOI: 10.32615/ps.2021.044  

Low temperature has negative effects on apple photosynthesis by inhibiting the accumulations of photosynthates and nitrogen. The interactive effects of low temperature and nitrogen application on photosynthetic parameters and the absorption and distribution of carbon and nitrogen in different organs were assessed to investigate if nitrogen application can relieve the low-temperature stress on gas exchange and the accumulations of carbon and nitrogen inside the apple plants. No matter under normal or low-temperature conditions, nitrogen application both improved the photosynthetic parameters including net photosynthetic rate, intercellular CO₂...

Photosynthetic apparatus performance and anatomical modulations of Alcantarea imperialis (Bromeliaceae) exposed to selenium during in vitro growth

J.P.R. MARTINS, S.W. MOREIRA, P.C.S. BRAGA, L.T. CONDE, R. CIPRIANO, A.R. FALQUETO, A.B.P.L. GONTIJO

Photosynthetica 2021, 59(4):529-537 | DOI: 10.32615/ps.2021.042  

Elements not usually included in culture medium formulations, such as selenium (Se), may have beneficial effects on micropropagated plants. We evaluated the effects of Se on the physiological and anatomical responses of Alcantarea imperialis during in vitro culture. Plants were cultured in a medium containing a gradient of Se concentrations (0, 4, 8, 16, or 32 µM Se). After 56 d, the growth traits, chlorophyll a fluorescence, and root and leaf anatomy were analyzed. The fresh mass declined at the highest Se concentration. Higher Se concentrations induced bigger stomata, while the stomatal density decreased. Plants cultured...

PSII photochemistry responses to drought stress in autochthonous and modern sweet cherry cultivars

I. MIHALJEVIĆ, M. VILJEVAC VULETIĆ, V. TOMAŠ, D. HORVAT, Z. ZDUNIĆ, D. VUKOVIĆ

Photosynthetica 2021, 59(4):517-528 | DOI: 10.32615/ps.2021.045  

In this study, the JIP test was used to assess the drought tolerance of two sweet cherry cultivars (Prunus avium L.) (modern and autochthonous). Plants were exposed to progressive drought by withholding water and their fast (< 1 s) chlorophyll fluorescence kinetics was evaluated. JIP test analysis showed that drought stress caused a greater decrease in performance indices (PI_ABS and PI_total) in a modern cultivar, as compared to an autochthonous one. Our results suggest that limited reoxidation of primary quinone electron acceptor (Q_A), higher amount of secondary quinone electron acceptor (Q_B^-)...

Effect of elevation on photosynthesis of young mango (Mangifera indica L.) trees

T.T. WUBSHET, Z. WANG, J. YANG, H. CHEN, D.A. SCHAEFER, S.D. GOLDBERG, P.E. MORTIMER, P. LU, J. XU

Photosynthetica 2021, 59(4):508-516 | DOI: 10.32615/ps.2021.040  

Anticipating warming related to climate change, commercial mango plantations in China have been shifting from lower to higher elevations. Such a practice may expose mangoes to climatic conditions that could affect photosynthesis. Photosynthesis research on mango has previously examined mature plantations but exploring adequate functions before the time of fruit production is necessary for later crop success. Therefore, we established two main commercial mango cultivars, Tainong No. 1 and Jinhuang, at 450 m and 1,050 m and examined their photosynthetic performance. Our results showed that photosynthetic capacity parameters, including maximum photosynthetic...

Effects of exposure of the leaf abaxial surface to direct solar radiation on the leaf anatomical traits and photosynthesis of soybean (Glycine max L.) in dryland farming systems

C. WANG, Y.M. DU, J.X. ZHANG, J.T. REN, P. HE, T. WEI, W. XIE, H.K. YANG, J.X. ZHANG

Photosynthetica 2021, 59(4):496-507 | DOI: 10.32615/ps.2021.038  

The frequent occurrence of monsoon winds usually leads to the formation of inverted soybean leaves. However, the effect of leaf inversion on photosynthetic capacity remains unclear. The responses of leaf anatomical traits, chlorophyll fluorescence induction kinetics parameters, photosynthetic capacity, and nonstructural carbohydrates of fully expanded leaves to inversion of leaves in two soybean cultivars were studied. Leaf inversion decreased the stomatal size and thickness of developed leaves. The net photosynthetic rate was significantly reduced under leaf inversion, which resulted from reduced excitation energy trapping and electron transport of...

Morphophysiological responses of Crambe abyssinica Hochst. lineages submitted to water deficit during flowering

P.C.S. BRAGA, J.P.R. MARTINS, R. BONOMO, A.R. FALQUETO

Photosynthetica 2021, 59(4):486-495 | DOI: 10.32615/ps.2021.039  

Water deficit (WD) at the start of the flowering stage can negatively affect the productivity of plants. The aim was to investigate the morphophysiological strategies of two crambe lineages (FMS CR 1326 and 1307) submitted to WD during the flowering stage and their connection with the progeny's germination. Plants were submitted to WD at the start of flowering for 12 d and then were irrigated again (water resumption, WR). As a control, plants were cultivated with uninterrupted daily irrigation. Under WD, reductions were observed in the stomatal conductance, the number of xylem vessels, and the mass of grains. Positive K- and L-bands occurred, indicating...

Assessing shade stress in leaves of turf-type tall fescue (Festuca arundinacea Schreb.)

Q. HE, D. LI

Photosynthetica 2021, 59(4):478-485 | DOI: 10.32615/ps.2021.037  

Shade treatment was applied to tall fescue with 30% full light. The results showed that shade increased chlorophyll (Chl) content per unit leaf mass, decreased the Chl a/b ratio in the mature leaves, and decreased effective quantum yield based on Chl fluorescence compared to the full light treatment. Shade stress did not cause increased contents of malondiadehyde at the early stages of leaf development. However, normalized vegetation indices were able to detect shade stress. Chloroplasts in the shaded leaves are arranged tightly against the periclinal cell wall and are in a spindle shape. There were no differences in the number of grana...

Impacts of low pH and low salinity induced by acid rain on the photosynthetic activity of green tidal alga Ulva prolifera

Z.F. ZHAO, Z.Y. LIU, S. QIN, X.H. WANG, W.L. SONG, K. LIU, L.C. ZHUANG, S.Z. XIAO, Z.H. ZHONG

Photosynthetica 2021, 59(4):468-477 | DOI: 10.32615/ps.2021.036  

Acid rain is a serious environmental problem and has obvious impacts on the growth, reproduction, and photosynthesis of terrestrial plants. Ulva prolifera, a main blooming species of green tides, was studied on its physiological response to acid rain. The photosynthetic parameters were determined under different conditions (salinity: 1, 10, 30‰; pH: 3.0, 3.5, 4.5; duration: 0.5, 1.0, 2.0 h) followed by 24-h recovering under natural conditions. Results showed 1-h treatment with pH 3.5 caused 50-70% reduction in the maximal quantum yield of PSII photochemistry (F_v/F_m) and effective quantum yield of PSII photochemistry...

Drought tolerance monitoring of apple rootstock M.9-T337 based on infrared and fluorescence imaging

D.T. GAO, C.Y. SHI, Q.L. LI, Z.F. WEI, L. LIU, J.R. FENG

Photosynthetica 2021, 59(SI):458-467 | DOI: 10.32615/ps.2021.035  

Apple rootstock seedling M.9-T337 was selected to explore the effect of drought stress. The findings indicated that the relative water content of both the leaf and soil gradually decreased with an increase in drought stress. The water-use efficiency of the leaves increased gradually but decreased sharply after 20 d of drought. Changes in the gas-exchange parameters and chlorophyll fluorescence parameters reflected the gradual decrease in the photosynthetic capacity of the plants with drought stress duration. Infrared thermal imaging showed significant temperature differences between the drought-stressed and control plants after 15 d of drought treatment....

Towards the quantitative and physically-based interpretation of solar-induced vegetation fluorescence retrieved from global imaging

S. VAN WITTENBERGHE, N. SABATER, M.P. CENDRERO-MATEO, C. TENJO, A. MONCHOLI, L. ALONSO, J. MORENO

Photosynthetica 2021, 59(SI):438-457 | DOI: 10.32615/ps.2021.034  

Due to emerging high spectral resolution, remote sensing techniques and ongoing developments to retrieve the spectrally resolved vegetation fluorescence spectrum from several scales, the light reactions of photosynthesis are receiving a boost of attention for the monitoring of the Earth's carbon balance. Sensor-retrieved vegetation fluorescence (from leaf, tower, airborne or satellite scale) originating from the excited antenna chlorophyll a molecule has become a new quantitative biophysical vegetation parameter retrievable from space using global imaging techniques. However, to retrieve the actual quantum efficiencies, and hence a true photosynthetic...

Chlorophyll fluorescence imaging for process optimisation in horticulture and fresh food production

W.B. HERPPICH

Photosynthetica 2021, 59(SI):422-437 | DOI: 10.32615/ps.2021.033  

Chlorophyll a fluorescence analysis (CFA) has been accepted to study postharvest activity and stability of photosynthesis of vegetables and salad greens, and some fruits. Commercial chlorophyll fluorescence imaging (CFI) systems may provide additional insight into spatial and temporal dynamics of photosynthesis. This yields valuable information on the effects of postharvest handling and processing (sorting, cutting, packaging, etc.) on physiological activity and 'internal quality' of green produce, and its changes. Here, meaning and physiological basics of relevant fluorescence parameters is briefly summarised, while major focus is on...

The love-hate relationship between chlorophyll a and water in PSII affects fluorescence products

C.R. GUADAGNO, D.P. BEVERLY, B.E. EWERS

Photosynthetica 2021, 59(SI):409-421 | 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 2021, 59(SI):399-408 | 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...

Can chlorophyll fluorescence imaging make the invisible visible?

R. VALCKE

Photosynthetica 2021, 59(SI):381-398 | 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 activityand plant stress

H.K. LICHTENTHALER

Photosynthetica 2021, 59(SI):364-380 | 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...

In honor of Hartmut Karl Lichtenthaler

G. GOVINDJEE

Photosynthetica 2021, 59(SI):361-363 | 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.