Physiological mechanism by which exogenous salicylic acid alleviates salt stress injury in Osmanthus fragrans seedlings

C.Y. GUO, E.Y. XUE, C.J. MENG, X.C. DU, J.D. ZHANG, M. YUE

Photosynthetica 2026, 64(2):126-136 | DOI: 10.32615/ps.2026.014  

Salicylic acid (SA) mitigates salt stress in plants, yet its combined effects with salinity on Osmanthus fragrans remain unstudied. O. fragrans is a key Chinese ornamental tree, whose growth and use are restricted by salinization. Therefore, we aimed to evaluate the effect of SA application on O. fragrans under salt stress. O. fragrans seedlings were subjected to NaCl, SA, and NaCl+SA treatments, and their physiological and growth responses to salt stress were examined. Under NaCl, plant height, leaf mass per area, photosynthetic rate, and pigments of O. fragrans decreased by 29.5, 20.6, 42.2, and 29.2%, respectively....

Happy 95^th birthday to Pierre Joliot, a brilliant scientist and a wonderful friend

G. GOVINDJEE, B.D. BRUCE

Photosynthetica 2026, 64(2):119-125 | DOI: 10.32615/ps.2026.019  

It is both a privilege and a pleasure to celebrate the upcoming 95^th birthday of Pierre Joliot, one of the most influential figures in modern photosynthesis research. Across more than seven decades of scientific activity, Pierre has transformed our understanding of oxygenic photosynthesis through pioneering studies of oxygen evolution, excitation-energy transfer, photosynthetic electron transport, and membrane bioenergetics. His discoveries helped establish fundamental concepts that continue to guide contemporary research, including the now-classic period-four oscillation of oxygen evolution and the mechanistic framework underlying the Kok-Joliot...

Effect of LED spectra on growth, physiology, and biochemical profiles of African marigold (Tagetes erecta L.)

N.H. NGUYEN, Q. PHAN, H.T.T. CHU, Q.C. TONG, T.T.H. HOANG, T.Q. TRAN, B.N. BUI, T.V. NGUYEN, Q.T. HO, H.H. CHU, P.T. DO

Photosynthetica 2026, 64(2):110-118 | DOI: 10.32615/ps.2026.018  

The effects of the light-emitting diode (LED) spectra on plant growth, flowering, and phytochemical accumulation of African marigold were assessed under controlled conditions. The combination of white, blue, and red LEDs prolonged the time to flower by up to 20 d compared to full white LEDs and other light treatments. The white LEDs are an insufficient lighting condition for marigold growth, indicated by the lower plant and flower biomass. The dichromatic blue-red light and the white-blue-red (WBR) light were most suitable for marigold growth, biomass production, as well as flower quantity and quality. In addition, the highest contents of flavonoids...

Drought stress-induced changes in PSII functioning in ecologically contrasting plants: chlorophyll fluorescence study of poikilohydric and homoiohydric species

J. HÁJEK, A. PUHOVKIN, J. LANG, S.I. UL HAQ, M. BERNATOVÁ, D. GIORDANO, J. SEKERÁK JR., M. BARTÁK

Photosynthetica 2026, 64(2):95-109 | DOI: 10.32615/ps.2026.012  

Dehydration reduces photosynthetic performance in leaves and other photosynthetic organs in response to drought. This decline is linked to changes in chlorophyll fluorescence, which reflects reduced photosystem II activity and increased protective non-photochemical quenching (NPQ). This study examined NPQ dynamics during desiccation across diverse species, including lichens, mosses, conifers, crops, and C₃ and C₄ plants, using the method of NPQ induction and relaxation curves. Gradual dehydration from a full-hydration state (RWC 100%) to complete dryness (RWC 0%) was applied in order to compare poikilohydric and homoiohydric species....

Revealing differences in the invasiveness of Sphagneticola trilobata under different light environments based on physiological and morphological plasticity

X.T. ZHENG, H. ZHU, Y.Z. ZHENG, Y.S. WANG, M. DING, J.X. WANG, Z.C. YU

Photosynthetica 2026, 64(2):82-94 | DOI: 10.32615/ps.2026.009  

Studies of the physiological and morphological characteristics of invasive plants contribute to understanding their invasive capacity. However, it remains unclear whether the same invasive plant species relies equally on morphological and physiological traits to enhance its invasiveness potential across different light habitats. In this study, the invasive plant Sphagneticola trilobata (L.) Pruski was used to examine eight morphological traits and nine physiological traits of the leaf under contrasting light conditions. Results revealed that under full light, growth, biomass, and all physiological traits, as well as most morphological traits...

Exploring prediction mechanisms for temperature-induced variation in maximum carboxylation rate from spectral reflectance across 450-850 nm in cucumber leaves

T. SHIBATA, H. YAMAGUCHI, S. KUBOTA, D. YASUTAKE, T. HIROTA, G. YOKOYAMA

Photosynthetica 2026, 64(2):73-81 | DOI: 10.32615/ps.2026.006  

Leaf spectral reflectance across 450-850 nm has been shown to predict maximum carboxylation rate (V_cmax), which varies with leaf temperature (T_leaf). However, the mechanism by which temperature-induced variation in V_cmax is predicted from reflectance remains unclear. The objective of this study was to explore this mechanism using spectral reflectance across 450-850 nm. We measured V_cmax across a range of T_leaf (18-31°C) and reflectance in cucumber (Cucumis sativus L.) leaves. Partial least squares regression models moderately predicted V_cmax...

Photosynthetic responses and growth dynamics of Allagoptera arenaria (Gomes) Kuntze (Arecaceae) in a chronosequence in a Restinga restoration area

A.J.G. JÚNIOR, M.M. MENDES, F.R. PIRES, A.A. FERNANDES, A.R. FALQUETO, L.F.T.D. MENEZES

Photosynthetica 2026, 64(2):64-72 | DOI: 10.32615/ps.2026.001  

Knowledge about plant species' growth dynamics is essential in restoring degraded environments. In this study, we evaluated the growth dynamics of Allagoptera arenaria (Gomes) Kuntze in a chronosequence of plantations in the Restinga. The sampling was taken from three populations with different planting ages (n = 12): group GI - 8 months; GII - 4 years; GIII - 7 years. We analyzed biometric measurements, leaf traits, photosynthetic pigments, and chlorophyll a fluorescence. The GI group's maximum quantum yield of primary photochemistry was significantly higher. On the other hand, the energy dissipation by heat was significantly...

Exploring the differences in the invasion potential of Sphagneticola trilobata in three invasive habitats based on photosynthetic and photoprotective capacities

Z.C. YU, H. ZHU, Y.Z. ZHENG, S.Y. YU, Y.F. LIU, X.L. LIN, C.L. PENG, X.T. ZHENG

Photosynthetica 2026, 64(1):52-63 | DOI: 10.32615/ps.2026.005  

Few studies have simultaneously assessed the growth characteristics and invasion potential of invasive plants in different habitats by integrating photosynthetic physiology with photoprotective strategies. In this study, we compared the growth, photosynthetic physiology, and photoprotective strategies of the widespread invasive plant Sphagneticola trilobata in three representative habitats: farmland, woodland, and riverside. Our results showed that S. trilobata exhibited the highest growth performance in farmland, which correlated with the highest net photosynthetic rate, electron transfer rate, and antioxidant substances. Plants from...

Elucidating copper ion interactions with carbonic anhydrase: insights from fluorescence quenching and thermodynamic analysis

M.S. SHABANOVA, I.M. HUSEYNOVA, S.K. ZHARMUKHAMEDOV, S.I. ALLAKHVERDIEV

Photosynthetica 2026, 64(1):43-51 | DOI: 10.32615/ps.2026.004  

Plant carbonic anhydrases (CAs) are essential metalloenzymes catalyzing reversible hydration of CO₂ to HCO₃⁻, thereby optimizing photosynthetic efficiency and carbon fixation in plants. They facilitate CO₂ delivery to Rubisco, enhance carbon assimilation, and play a role in plant responses to stresses (such as drought, high salinity) by modulating stomatal conductance and internal CO₂ concentrations. Despite the well-established physiological importance of plant CAs, the influence of metal ions, particularly copper (Cu²⁺), on their structure and activity remains inadequately understood....

Characteristics of photosynthetic function in different leaf ages of 'Tieton' sweet cherry in a greenhouse

J.Y. AI, F. CAI, Y. CHEN, M.L. HE, C. LUO, Q.J. ZHANG

Photosynthetica 2026, 64(1):36-42 | DOI: 10.32615/ps.2026.003  

To clarify the stages of leaf growth and development, the young leaf stage was identified at 0-20 d after emergence (DAE). The functional stage was at 20-100 DAE, with the highest functional point at 80 DAE. The leaf aging stage occurred at 100-220 DAE. During the functional stage of leaf development, optimal photosynthetic parameters and anatomical structures were achieved; the leaf area (LA) was at its largest, and the thickening rate of the palisade parenchyma was the fastest. The palisade parenchyma and LA were closely related to photosynthetic characteristics. Stomatal opening and closing, and stomatal density were greater in the functional stage...

Impact of tetraploidization on morphophysiological leaf traits in the drought tolerant 'de Ramellet' tomato landrace

P. CERDÁ-BENNASSER, M. FULLANA-PERICÀS, P. AGUILÓ-NICOLAU, J. PELLICER, J. GALMÉS, M.À. CONESA

Photosynthetica 2026, 64(1):26-35 | DOI: 10.32615/ps.2026.002  

Tetraploidization was induced in the drought-tolerant tomato landrace 'de Ramellet' to evaluate its physiological and anatomical response under well-watered (WW) and water-deficient (WD) conditions. Under WW, tetraploid plants exhibited approximately 40% lower stomatal density and approximately 80% larger stomata than diploids. Net photosynthetic rate (P_N), intrinsic water-use efficiency, and intercellular CO₂ concentration remained unchanged between diploids and tetraploids. Under WD, both genotypes reduced P_N and stomatal conductance by similar proportions; however, only diploids decreased leaf area...

A reexamination of the Kitajima and Butler (1975) model for relating chlorophyll a fluorescence to photochemistry

I.V. KONYUKHOV, A. STIRBET, A.B. RUBIN, G. GOVINDJEE

Photosynthetica 2026, 64(1):12-25 | DOI: 10.32615/ps.2025.038  

The main assumptions of the well-known Kitajima and Butler (1975) model, describing the relationship between the ratio of the maximum variable chlorophyll a fluorescence to the maximum fluorescence (F_V/F_M) and the photochemical quantum yield of PSII (Φ_Po), have been analyzed. Using the experimental data from the literature, potential "weak points" of this model are discussed, as well as the reasons for the differences between the F_V/F_M values and the actual Φ_Po values. Special attention is focused on the fluorescence measurement procedures using the saturating single...

Characterizing the CO₂-response curve in photosynthesis and photorespiration: an innovative model for C₃ plant species

H.-J. KANG, T. AN, X.-L. YANG, Z.-P. YE, F.-B. WANG

Photosynthetica 2026, 64(1):1-11 | DOI: 10.32615/ps.2025.030  

We introduce a novel model for characterizing the CO₂-response curve in photosynthesis, addressing the limitations of the Farquhar-von Caemmerer-Berry (FvCB) model by providing a more comprehensive framework for understanding photosynthetic responses to varying CO₂ concentrations in C₃ plants. The FvCB model, while instrumental in interpreting the photosynthetic response to CO₂, does not directly estimate critical parameters such as maximum net photosynthetic rate, transit point from RuBP- to TPU-limited photosynthesis, and the CO₂ compensation point in the presence of day respiration (R_day)....

Twenty years of the International Conferences on Photosynthesis and Hydrogen Energy Research for Sustainability

A.W.D. LARKUM, R. SUBRAMANYAM, G. GOVINDJEE, S.I. ALLAKHVERDIEV

Photosynthetica 2025,63(4):374-384 | DOI: 10.32615/ps.2025.035  

The International Conference on "Photosynthesis and Hydrogen Energy Research" was inaugurated in 2004 in Trois Rivières, Canada, as "Photosynthesis and Post-Genomics Era". It was conceived by its founders, Suleyman I. Allakhverdiev (Russia), Vyacheslav (Slava) Klimov (Russia), Robert Carpentier (Canada), and Prasanna Mohanty (India) to be an alternating conference to the bigger International Congress on Photosynthesis, which was then held every three years. The name was changed to the International Conference on Photosynthesis (ICP) in 2011. In 2013, "Hydrogen Production" was added, and then finally the current name, "International Conference...

Recent advances in plant stress analysis using chlorophyll a fluorescence

K.W. CHANG, H. TANG, L.J. FU, Q. XIA, Z.Y. PAN, J.L. TAN, V. LYSENKO, Y. GUO

Photosynthetica 2025,63(4):359-373 | DOI: 10.32615/ps.2025.037  

Chlorophyll fluorescence (ChlF), a sensitive, real-time, and nondestructive indicator of photosynthesis, enables noninvasive elucidation of the complex physiological and biochemical processes of plants. It plays a unique and important role in plant research, ecological evaluation, and agriculture. To provide a holistic picture of research on ChlF applications over the past decade, a knowledge map was first conducted, which revealed six major areas of ChlF applications in plant stress evaluation and reduction, including drought stress, temperature stress, salt stress, water stress, toxicity stress, and nitrogen stress. This work then systematically...

Phytomelatonin and post-drought stomatal recovery: psychotropic-like signaling in guard-cell dynamics

I. ACCOSSATO

Photosynthetica 2025,63(4):358 | DOI: 10.32615/ps.2025.039  

Unravelling the differential responses of critically endangered Onobrychis conferta populations to drought and salinity stress

A. SAKHRAOUI, H.B. LTAEIF, J.M. CASTILLO, S. ROUZ

Photosynthetica 2025,63(4):346-357 | DOI: 10.32615/ps.2025.034  

Understanding stress responses of endangered plants is vital for their conservation under climate change. We examined the effects of iso-osmotic drought (PEG) and salinity (NaCl) on the growth and physiology of three populations of the critically endangered legume Onobrychis conferta subsp. conferta (OC1, OC2, OC3) endemic to North-Western Tunisia. Both stresses reduced photosynthesis, stomatal conductance, intercellular CO₂, and carboxylation efficiency, while increasing intrinsic water-use efficiency. PSII photoinhibition (F_v/F_m decline) occurred after 6 d. Prolonged stress suppressed growth and water...

Increase in photosynthetic carbon assimilation and gas exchange through foliar application of melatonin in green bean plants

C.A. RAMÍREZ-ESTRADA, E.H. OCHOA-CHAPARRO, E. NAVARRO-LEÓN, J.C. ANCHONDO-PAÉZ, J.J. PATIÑO-CRUZ, C.L. FRANCO-LAGOS, A. ALVAREZ-MONGE, E. SÁNCHEZ

Photosynthetica 2025,63(4):340-345 | DOI: 10.32615/ps.2025.036  

Crop productivity depends largely on photosynthetic efficiency, which is key to converting light energy into assimilates for biomass accumulation. The use of biostimulants such as melatonin (MEL) has emerged as a sustainable alternative to improve internal processes in plants and increase production. However, its effect on beans has not yet been clearly described. This study evaluated the foliar application of MEL on physiological and productive variables of Strike beans (Phaseolus vulgaris L.). The plants were grown in vermiculite/perlite substrate (2:1) for 60 d, applying MEL [0, 1, 10, and 100 µM] weekly from 15 d after sowing. All...

Gordon Research Conference on Photosynthesis 2025: Mechanisms of the Process Driving the Biosphere Through the Lenses of Experiment and Computation

C.J. GISRIEL, J. LIU, D.A. FLESHER, K.E. REDDING

Photosynthetica 2025,63(4):332-339 | DOI: 10.32615/ps.2025.033  

Herein, we report on the 2025 Gordon Research Conference (27 July-1 August) and its preceding Gordon Research Seminar (26-27 July) on Photosynthesis, entitled "Mechanisms of the Process Driving the Biosphere Through the Lenses of Experiment and Computation". Both were held at Sunday River Resort in Newry, Maine, USA. The seminar and conference brought together an international group of photosynthesis researchers to discuss the most cutting-edge work uncovering photosynthetic mechanisms via computation, genetic manipulation, systems biology, structural biology, and much more.

Additional far-red light improves the growth and resistance of the photosynthetic apparatus of Lactuca sativa L. to high-intensity light

V.D. KRESLAVSKI, P.P. PASHKOVSKIY, A.N. SHMAREV, A.Yu. KHUDYAKOVA, V.V. STROKINA, A.A. IVANOV, A.A. KOSOBRYUKHOV, S.I. ALLAKHVERDIEV

Photosynthetica 2025,63(4):322-331 | DOI: 10.32615/ps.2025.032  

The effects of additional far-red light (FRL) on the growth parameters, photosynthetic activity, and pro- or antioxidant balance of Lactuca sativa L. plants grown for 30 d were studied. The plants were grown under white light-emitting diodes with equal PAR intensities at red/far-red light ratios of 0.29, 0.89, and 1.67 and without FRL. Compared to the absence of the FRL, growth at a 0.29 ratio caused an increase in plant biomass and leaf area, but a decrease in PSII activity, net photosynthetic rate (P_N) per unit area, and stomatal conductance. High irradiance for 4 h at 1,000 μmol(photon) m^-2 s^-1...

Spectral light quality differentially modulates PSII energy partitioning among soybean genotypes

M. MARTÍNEZ-MORÉ, S. SIMONDI, M.M. SAINZ, V. BONNECARRÈRE, S. FERNÁNDEZ, G. QUERO

Photosynthetica 2025,63(4):309-321 | DOI: 10.32615/ps.2025.029  

Cultivated soybean is a globally important crop; understanding its responses to different light spectra within the canopy is essential, especially considering the limited agricultural area. Energy flux and spectral quality are key components of the light environment that determine photosynthesis and, consequently, plant growth. These factors influence the composition and structure of photosystem II, thereby affecting energy partitioning between photochemical and nonphotochemical processes. This study evaluated the photosynthetic performance of two soybean genotypes under four light environments with distinct spectral compositions but equal energy flux....

Evaluating physiological traits of Coffea canephora clones intercropped with Hevea brasiliensis

I.D.P. PEREIRA, S. DOUSSEAU-ARANTES, J.A. MACHADO FILHO, L.O. ARANTES, M.M. MENDES, V.F. SANTOS, G.A.R. DE SOUZA, B. CERRI NETO, D. CASSOL, A.R. FALQUETO

Photosynthetica 2025, 63(3):297-308 | DOI: 10.32615/ps.2025.028  

In this study, we evaluated the physiological response of the photosynthetic apparatus [using chlorophyll a fluorescence (ChlaF) measurements], changes in leaf nutrient contents, and productivity of 16 Coffea canephora clones grown alone (NC, full sunlight) or intercropped with Hevea brasiliensis (IC, shaded). Shade from H. brasiliensis trees influenced the physiological performance of coffee plants. Some of these coffee clones achieved clear responses to shading by rubber trees, indicating that the responses of coffee plants to intercropping are genotype-specific. The PSII complex of the NC plants was more susceptible...

Avoiding leakage when classifying drought stress from OJIP fluorescence - comment on Xia et al. (2025)

E.P. PASTORE

Photosynthetica 2025, 63(3):296 | DOI: 10.32615/ps.2025.031  

Role of nitrogen utilization in facilitating photosynthetic compensation of soybean under vertically heterogeneous light

X.R. MA, X.M. SONG, E.Z. ZHANG, J.B. DU, X. SUN

Photosynthetica 2025, 63(3):291-295 | DOI: 10.32615/ps.2025.026  

Photosynthetic compensation enables high-density planted crops to use the available light efficiently. However, the underlying mechanism remains unclear. Herein, soybeans (Glycine max L. Merr.) were treated with vertically heterogeneous light (HL) to simulate the light conditions in high-density planting. The net photosynthetic rate (P_N) increased in upper unshaded leaves (UL) while it decreased in lower shaded leaves (LL) under HL. This evident photosynthetic compensation was accompanied by a preferential distribution of N to UL. Correspondingly, the amounts of chlorophyll (Chl) and Rubisco increased in UL. At the...

Cadmium and high light stress interactions highlight limits of PSII in Arabidopsis thaliana

R. SINGH

Photosynthetica 2025, 63(3):288-290 | DOI: 10.32615/ps.2025.027  

A thank you note for Julian Eaton-Rye, the wonderful staff at Photosynthetica, and all the scientists who participated in the 2018 special issue

G. GOVINDJEE

Photosynthetica 2025, 63(3):282-287 | DOI: 10.32615/ps.2025.025  

In honor of Reto Jörg Strasser: A pioneer of chlorophyll a fluorescence research

A. STIRBET, G. GOVINDJEE, A. SRIVASTAVA

Photosynthetica 2025, 63(3):267-281 | DOI: 10.32615/ps.2025.024  

Chlorophyll (Chl) a fluorescence measurements are widely used in the study of photosynthesis, and Reto Strasser is a well-known pioneer in this domain. In 2019, the current authors, together with Vineet Soni, and Neera Bhalla Sarin, celebrated his 75^th birthday. Here, we pay tribute to him on his 82^nd birthday through a brief description of the key results we had obtained with him, over the years, on the understanding and exploitation of the OJIP Chl a fluorescence transient. The topics of these studies have been quite diverse, from the oxygen clock, the bicarbonate effect in Photosystem II, the adaptability of...

Variations in the photoprotective responses of trees and seedlings of the endangered Pitavia punctata (Ruiz & Pav.) Molina

S. ESPINOZA, D. MUÑOZ-CONCHA

Photosynthetica 2025, 63(3):262-266 | DOI: 10.32615/ps.2025.023  

Pitavia punctata (Ruiz & Pav.) Molina ('Pitao') is an endangered species that regenerates under the shade. We monitored the photochemical efficiency of photosystem II in four localities spanning the geographical distribution of the species in Central Chile. Technical fluorescence parameters and JIP-test-derived parameters were measured in trees (up to 15 m) and seedlings (< 50 cm). We observed significant effects of the type of plant and locality on the performance index (PI_ABS) and maximum fluorescence (F_M). PI_ABS was higher in trees from the Los Barros locality (PI_ABS = 41), whereas seedlings located...

Leaf gas exchange and photosynthetic light-response curves of cassava genotypes under drought stress during the early growth stage and after recovery

K. VONGCHAROEN, S. SANTANOO, P. ITTIPONG, P. BANTERNG, N. VORASOOT, S. JOGLOY, P. THEERAKULPISUT

Photosynthetica 2025, 63(3):246-261 | DOI: 10.32615/ps.2025.021  

This study aimed to gain insights into the photosynthesis capacity and genotypic differences in response to drought imposed at an early growth stage of cassava. Leaf water potential (LWP), leaf gas exchange, and photosynthetic light-response curves were investigated in six field-grown cassava genotypes under full irrigation and drought imposed for 60 d during 3-5 months after planting. During the drought period, mean LWP at predawn (LWP_pre) was significantly lower than that in the control plants, while the mean midday LWP (LWP_mid) was similar. During the drought period, the mean stomatal conductance was reduced from 0.36 to...

Photosynthetic characteristics of upland cotton (Gossypium hirsutum) recessive genic male sterile line YA-1 with virescent trait

N. YANG, X.X. LIU, X.P. ZHANG, H.Q. DENG, X.L. SHEN, C.M. TANG

Photosynthetica 2025, 63(3):234-245 | DOI: 10.32615/ps.2025.018  

The upland cotton strain YA-1 can be used for hybrid seed production and recurrent selection. However, the effect of YA-1 virescent phenotype on photosynthetic traits remains unclear. This study demonstrated that the chlorophyll and carotenoid contents, light-saturation point, light-compensation point, and PSⅡ reaction center activities are lower than those of green leaves of wide type. In contrast, light-energy utilization efficiencies, net photosynthetic rate, transpiration rate, stomatal conductance, concentrations of Rubisco and phosphoenolpyruvate carboxylase, photosynthetic performance indices, and energy distribution parameters of the...