From spectrum to yield: advances in crop photosynthesis with hyperspectral imaging

D. PANDA, S. MOHANTY, S. DAS, J. SENAPATY, D.B. SAHOO, B. MISHRA, M.J. BAIG, L. BEHERA

Photosynthetica 2025, 63(2):196-233 | DOI: 10.32615/ps.2025.012  

Ensuring global food security requires noninvasive techniques for optimizing resource use and monitoring crop health. Hyperspectral imaging (HSI) enables the precise analysis of plant physiology by capturing spectral data across narrow bands. This review explores HSI's role in agriculture, particularly its integration with unmanned aerial vehicles, AI-driven analytics, and machine learning. These advancements allow real-time monitoring of photosynthesis, chlorophyll fluorescence, and carbon assimilation, linking spectral data to plant health and agronomic decisions. Key indicators such as solar-induced fluorescence and vegetation indices enhance crop...

The combined effect of Cd and high light stress on the photochemical processes in Arabidopsis thaliana

D. GIORDANO, M. BARTÁK, J. HÁJEK

Photosynthetica 2025, 63(2):182-195 | DOI: 10.32615/ps.2025.020  

The adverse effects of cadmium on plants are accompanied by a limitation of photosynthesis, due to the production of reactive oxygen species, leading to oxidative damage to PSII and the disruption of key protein complexes involved in photosynthetic pathways. We investigated the effects of cadmium stress combined with high light in Arabidopsis thaliana, as dependent on the cadmium dose applied. The aim was to investigate the combined effect of the two stressors on photochemical processes with the hypothesis that Cd stress enhances the negative effect of the high light. The plants were treated with 0, 1, 10, and 50 mM Cd added as CdCl₂...

Thermal stability changes of photosynthesis during osmotic and salt stress in wheat varieties cultivated in Central Europe and Mediterranean North Africa

A. ALLEM, R. TARNAI, S.B. TÓTH, W.A.E. ABIDO, S. DULAI

Photosynthetica 2025, 63(2):165-181 | DOI: 10.32615/ps.2025.019  

The thermal stability of photosynthetic apparatus under osmotic/salt stress was examined in wheat cultivars grown under different climatic conditions. The thermostability of nonstressed plants did not differ significantly from each other and it was not improved by osmotic treatment in the absence of light. In contrast, the salt stress resulted in better thermostability. This was also manifested in the temperature dependence of maximal quantum yield of PSII photochemistry. The temperature dependence of steady-state fluorescence and other photosynthetic parameters indicated a moderate reduction in thermal sensitivity of photosynthesis in well-watered...

Tribute to late Prof. Sakae Katoh (1932-2025): discovery of plastocyanin and his research in photosynthesis

K. SONOIKE

Photosynthetica 2025, 63(2):162-164 | DOI: 10.32615/ps.2025.022  

Synergistic effects of drought and heat stress on Medicago truncatula: understanding growth response and photosynthetic mechanisms

N. RESSAISSI, W. MNAFGUI, N. MAIZA, F. ZRIBI, W. ZORRIG, N. LUDIDI, M.T. SANCHEZ-BALLESTA, M. BADRI

Photosynthetica 2025, 63(2):151-161 | DOI: 10.32615/ps.2025.008  

Drought and heat stress significantly threaten forage crop development and photosynthetic activity in the Mediterranean region. This study investigated the physiological responses and photosynthetic activity of two Medicago truncatula lines TN6.18 and F83005.5 (F83), to single and combined heat and drought stress treatments. Biomass traits, leaf gas exchange, and photosystem activities were evaluated. Our findings indicate a reduction in biomass parameters under heat, drought, and combined stress on both lines, particularly in F83. The stomatal conductance and photosynthetic parameters exhibited differential responses, with F83 reducing...

Increased brassinolide accumulation and increased growth in low-light-grown transgenic tobacco

R. GREBENOK, T. UGINE, M. GALANTE, N. GREBENOK, H. IQBAL, N. OLSZEWSKI, X. KRULL, T. LINGENFELTER, R. SEDANO, E. CORIGLIANO, A. GREBENOK

Photosynthetica 2025, 63(2):140-150 | DOI: 10.32615/ps.2025.016  

Transgenic tobacco, demonstrating bacterial cholesterol oxidase (CO) activity in the chloroplast, grown at PAR ~280 μmol(photon) m^-2s^-1 (low light), contained thylakoid membranes that include a greater variety of steroids and had reduced contents of sterol and sterol-esters per milligram chlorophyll in comparison to controls. The mature transgenic plants, grown at low light, demonstrate a ~3× larger root dry mass, ~3× larger stem dry mass, ~2× larger leaf dry mass, ~2× increased leaf number, and ~5× increased flower number than controls. Mature transgenic flowering plants, develop to first flower ~2× faster and grow ~30% taller...

Green manure can be an auxiliary factor against dynamic photoinhibition in Dalbergia ecastophyllum (L.) young trees in areas impacted by mining

M.M. MENDES, I.F. RIBEIRO, V.F.D. SANTOS, F.R. PIRES, A.A. FERNANDES, L.F.T.D. MENEZES, R. BONOMO, D. CASSOL, J.P.R. MARTINS, A.R. FALQUETO

Photosynthetica 2025, 63(2):129-139 | DOI: 10.32615/ps.2025.015  

This study evaluated the efficiency of green manure (+GM) on PSII efficiency throughout the day in Dalbergia ecastophyllum. The experiment was carried out in a disabled clay extraction deposit, located approximately 30 km south of São Mateus city (Espírito Santo State, Brazil). Chlorophyll (Chl) index, Chl a fluorescence, and plant growth were measured in the summer, after 12 months of planting. +GM improved the photochemical performance of D. ecastophyllum, reducing the occurrence of photoinhibition throughout the day. +GM increased the photochemical quantum yield, the probability of a photon absorbed to move beyond quinone...

Effect of strobilurin fungicide on the initial growth of common bean plants

A.C.P. ROCHA, J.F. MIRANDA, L.B. DAS NEVES, M.M. MENDES, A.S. AMORIM, G.S. MORAIS, J.P.R. MARTINS, M.B. DA SILVA, A.B.P.L. GONTIJO, A.R. FALQUETO

Photosynthetica 2025, 63(2):116-128 | DOI: 10.32615/ps.2025.017  

Strobilurin fungicides, such as pyraclostrobin (PCL), can impact plant metabolism and morphophysiological parameters. This study evaluated the effects of PCL on Phaseolus vulgaris L., subjecting seeds to imbibition in different concentrations (0, 112, 450; and 1,800 mg L^-1) for 10 and 30 min. After germination in a growth chamber, germination, growth, biomass, anatomical, and physiological characteristics were analyzed. The study confirmed that PCL interference was proportional to the concentration and seed imbibition time, affecting the percentage of germinated seeds in the first count, normal and abnormal seedlings, and dead seeds....

Potential mechanisms for the rapid post-drought reversal of ABA-induced stomatal closure by melatonin, 5-aminolevulinic acid, and brassinosteroids

M. WASEEM, M.M. HASAN, Y. HAZZAZI, B.M. ALHARBI, M.U. GHANI, P. AHMAD, M. CARRIQUÍ

Photosynthetica 2025, 63(2):104-115 | DOI: 10.32615/ps.2025.011  

The regulation of stomatal movements is crucial for plants to optimize gas exchange and water balance. The plant hormone abscisic acid (ABA) triggers stomatal closure in response to drought, effectively minimizing water loss to prevent hydraulic failure. However, it significantly constrains photosynthesis, restricting plant growth and productivity. Therefore, rapid post-drought stomatal opening is crucial for earlier photosynthetic recovery. This review explores how phytohormones or plant growth regulators reverse ABA-induced stomatal closure. Phytomelatonin, 5-aminolevulinic acid, and brassinosteroids promote stomatal reopening by either ABA degradation...

Dr. Autar Krishen Mattoo (1943-2024): an outstanding plant biologist with a focus on photosynthesis

A.K. HANDA, M. EDELMAN, W.W. ADAMS III, G. GOVINDJEE

Photosynthetica 2025, 63(2):95-103 | DOI: 10.32615/ps.2025.014  

We provide here the academic life of Dr. Autar Krishen Mattoo (1943-2024), including his role as a research leader at the United States Department of Agriculture and his outstanding contributions in photosynthesis, plant physiology and molecular biology with a focus to enhance nutrients. His work included ways to regulate Photosystem II (PSII) reaction center proteins, as well as to exploit, for our benefit, the role of polyamines in the plant world. Further, he provided the basis for beneficial aspects of sustainable agriculture systems and for selecting genes/proteins that provide better growth, higher disease resistance, and tolerance from abiotic...

Natalia Evgenievna Belyaeva (1945-2025)

A.B. RUBIN, G.YU. RIZNICHENKO

Photosynthetica 2025, 63(2):93-94 | DOI: 10.32615/ps.2025.013  

The 12^th International Conference on "Photosynthesis and Hydrogen Energy Research for Sustainability 2024": in honour of John Allen,Eva-Mari Aro, İbrahim Dinçer, Kazunari Domen, Elizabeth Gantt, and Andrey Rubin

M. ZIVCAK, J. KERN, T. TOMO, G. SOYKAN, J.J. EATON-RYE, S.I. ALLAKHVERDIEV, B.D. BRUCE

Photosynthetica 2025, 63(2):81-92 | DOI: 10.32615/ps.2025.010  

The 12^th International Conference "Photosynthesis and Hydrogen Energy Research for Sustainability 2024" was organised in honour of John Allen, Eva-Mari Aro, İbrahim Dinçer, Kazunari Domen, Elizabeth Gantt, and Andrey Rubin, by Bahçeşehir University in Istanbul from 13 to 19 October 2024. The International Society of Photosynthesis Research (ISPR) and the International Association for Hydrogen Energy (IAHE) supported the event. In the brief report, we provide a summary of the conference, the scientific contributions of honoured scientists, and a brief content of individual sessions. We specifically focused on the participation of young...

Determination of rice (Oryza sativa L.) drought stress levels based on chlorophyll a fluorescence through independent component analysis

Q. XIA, H. TANG, J.L. TAN, S.I. ALLAKHVERDIEV, Y. GUO

Photosynthetica 2025, 63(1):73-80 | DOI: 10.32615/ps.2025.009  

Sensing rice drought stress is crucial for agriculture, and chlorophyll a fluorescence (ChlF) is often used. However, existing techniques usually rely on defined feature points on the OJIP induction curve, which ignores the rich physiological information in the entire curve. Independent Component Analysis (ICA) can effectively preserve independent features, making it suitable for capturing drought-induced physiological changes. This study applies ICA and Support Vector Machine (SVM) to classify drought levels using the entire OJIP curve. The results show that the 20-dimensional ChlF features obtained by ICA provide superior classification performance,...

Subtropical lichens from the Afromontane can display rapid photosynthetic acclimation to simulated climate change

N.T. NDHLOVU, T.N. KHUZWAYO, F.V. MINIBAYEVA, R.P. BECKETT

Photosynthetica 2025, 63(1):64-72 | DOI: 10.32615/ps.2025.005  

Afromontane forests are an important part of the KwaZulu Natal region of southern Africa, having a distinctive flora with a high proportion of endemic species, and lichens are keystone members. Unlike other continental areas, KwaZulu Natal climate change is predicted to increase rainfall and cloudiness. In the present study, hydrated Afromontane lichens from both exposed and shaded microhabitats were given either constant [100 µmol(photon) m^-2 s^-1] or fluctuating [0, 200, 0 µmol(photon) m^-2 s^-1] light for 8 h a day for 3 d and changes monitored in nonphotochemical quenching (NPQ) and rates of...

Response of leaf internal CO₂ concentration and intrinsic water-use efficiency in Norway spruce to century-long gradual CO₂ elevation

J. ŠANTRŮČEK, J. KUBÁSEK, J. JANOVÁ, H. ŠANTRŮČKOVÁ, J. ALTMAN, J. TUMAJER, M. HRÁDKOVÁ, E. CIENCIALA

Photosynthetica 2025, 63(1):51-63 | DOI: 10.32615/ps.2025.006  

The strategies of Norway spruce [Picea abies (L.) Karst.] to increasing atmospheric CO₂ concentration (C_a) are not entirely clear. Here, we reconstructed centennial trajectories of leaf internal CO₂ concentration (C_i) and intrinsic water-use efficiency (WUE_i) from the amount of ¹³C in tree-ring cellulose. We collected 57 cores across elevations, soil, and atmospheric conditions in central Europe. Generally, WUE_i and C_i increased over the last 100 years and the C_i/C_a ratio remained almost constant....

Heat-induced F₀-fluorescence rise is not an indicator of severe tissue necrosis in thermotolerance assays of young and mature leaves of a tropical tree species, Calophyllum inophyllum

K. WINTER, M. GARCIA, A. VIRGO

Photosynthetica 2025, 63(1):46-50 | DOI: 10.32615/ps.2025.004  

In heating experiments with leaves, the temperature at which dark-level F₀ chlorophyll a fluorescence begins to rise, T_crit, is widely used as an indicator of photosystem II thermotolerance. However, little is known about how T_crit correlates with irreversible leaf tissue damage. Young and mature leaves of the tropical tree species Calophyllum inophyllum were heated stepwise from 30 to 55°C, at 1°C min^-1. T_crit was 47°C in young leaves and 49°C in mature leaves. Contrary to the higher T_crit in mature leaves, heating to 55°C elicited greater tissue damage in mature...

Relative importance of chlorophyll metabolic genes for light-induced greening of potato tubers

S. TANIOS, T. THANGAVEL, A. EYLES, R.S. TEGG, C.R. WILSON

Photosynthetica 2025, 63(1):37-45 | DOI: 10.32615/ps.2025.003  

Potato tuber greening occurs due to the chlorophyll accumulation upon exposure to light, however, fundamental information on tuber chlorophyll metabolism is lacking. We measured the effect of varying light exposure (0, 48, 96, and 168 h) on chlorophyll concentration and gene expression of enzymes in the chlorophyll metabolic pathway in the potato varieties that differ in greening propensity. Greening was associated with the upregulation of genes involved in chlorophyll biosynthesis, particularly glutamyl-tRNA reductase 1, magnesium-chelatase subunit H, and magnesium-protoporphyrin IX monomethyl ester cyclase, and downregulation of genes involved in...

Hans Kautsky's groundbreaking discovery(ies) in 1931, its scientific environment, and the ensuing developments

U. SCHREIBER, H.K. LICHTENTHALER

Photosynthetica 2025, 63(1):28-36 | DOI: 10.32615/ps.2025.007  

In 1931, Hans Kautsky discovered not only chlorophyll (Chl) fluorescence induction ("Kautsky effect") in green leaves but also metastable excited oxygen, now known as singlet oxygen, which he showed to act as an intermediate in dye-sensitized photooxidations of organic substances in vitro ("Kautsky mechanism"). While at that time practically nothing was known about the primary reactions of photosynthesis, Kautsky firmly believed that "his" mechanism is also effective in the "Chl-sensitized" conversion of light energy into chemically fixed energy. This erroneous assumption complicated the interpretation of rapid Chl fluorescence induction kinetics,...

The story of my life into and through the science of photosynthesis: a personal perspective

J.J.S. VAN RENSEN

Photosynthetica 2025, 63(1):20-27 | DOI: 10.32615/ps.2025.001  

I present here the story of my personal and scientific life. I provide information on my parents, my childhood, schooling, education at the Wageningen Agricultural University, and the work for my PhD degree on the action of some herbicides on photosynthesis under the guidance of Professor Evert Christiaan Wassink. After graduation, I obtained a position as a professor. In 1977, I spent a one-year sabbatical with Professor Govindjee at the University of Illinois at Urbana-Champaign, USA. This was the start of a long-time and successful cooperation on the effects of bicarbonate on Photosystem II. The research on the impact of herbicides on photosynthesis...

Sixty years of research on photosynthesis: a personal scientific autobiography

T. OGAWA

Photosynthetica 2025, 63(1):10-19 | DOI: 10.32615/ps.2025.002  

The following scientific autobiography is presented here as a homage to Professor Kazuo Shibata, who is the one who led me to do research in photosynthesis. He had invited me to Riken (The Institute of Physical and Chemical Research), and had launched the Japan-US Collaboration Project on "The Solar Energy Conversion by Means of Photosynthesis" and had invited many international scientists to Riken. My research, under Shibata, started on using a sensitive method for the determination of chlorophyll b, and of SDS-PAGE for the pigment protein complexes of the two photosystems. After Shibata had passed away at the age of 66, I found post-illumination...

The resistance of Solanum lycopersicum photosynthetic apparatus to high-intensity blue light is determined mainly by the cryptochrome 1 content

V. KRESLAVSKI, P. PASHKOVSKIY, A. ASHIKHMIN, A. KOSOBRYUKHOV, A. SHMAREV, A. IVANOV, V. STROKINA, M. VERESHCHAGIN, G. SHIRSHIKOVA, S.I. ALLAKHVERDIEV

Photosynthetica 2025, 63(1):1-9 | DOI: 10.32615/ps.2024.043  

The effects of deficiency of cryptochrome 1 (CRY1), phytochrome B2 (phyB2) and the photoreceptor signalling DET-1 protein (hp-2 mutant) on photosynthesis and pro-/antioxidant balance in Solanum lycopersicum exposed to high-intensity blue light [HIBL, 72 h, 500/1,000 μmol(photon) m^-2 s^-1] were studied. Noticeable photoinhibition of photosynthesis and PSII was found in all these variants. However, the greatest decrease in photosynthesis and PSII activity was observed in the cry1 mutant. The difference among the other options was less pronounced. This low resistance of the cry1 mutant to HIBL is associated...

On "P750s" in cyanobacteria: A historical perspective

G. GOVINDJEE, L.O. BJÖRN, R.E. BLANKENSHIP

Photosynthetica 2024, 62(4):406-408 | DOI: 10.32615/ps.2024.042  

Impact of exogenous rhamnolipids on plant photosynthesis and biochemical parameters under prolonged heat stress

M.A. BOUCHRATI, S. VILLAUME, J.F. GUISE, I. FEUSSNER, N. VAILLANT-GAVEAU, S. DHONDT-CORDELIER

Photosynthetica 2024, 62(4):393-405 | DOI: 10.32615/ps.2024.041  

High temperatures severely affect plant growth and development leading to major yield losses. These temperatures are expected to increase further due to global warming, with longer and more frequent heat waves. Rhamnolipids (RLs) are known to protect several plants against various pathogens. To date, how RLs act under abiotic stresses is unexplored. In this study, we aimed to investigate whether RLs could modify Arabidopsis thaliana physiology during prolonged heat stress. Measurement of leaf gas exchange and chlorophyll fluorescence showed that heat stress reduces photosynthetic rate through stomatal limitation and reduction of photosystem...

Chloroplast antioxidant reactions associated with zinc-alleviating effects on iron toxicity in wheat seedlings

Y.L. XU, J.Y. GUO, Z. ZHANG, R.R. MA, H. MA, Y. ZHANG, Y.L. YANG

Photosynthetica 2024, 62(4):381-392 | DOI: 10.32615/ps.2024.038  

This study aimed to explore the mechanism by which Zn retards Fe toxicity by analyzing the morphological, photosynthetic, and chloroplast physiological parameters of wheat seedlings treated with either single or combined Zn and Fe. Different behavior of the seedlings was observed under untreated and treated conditions. The most discriminating quantitative traits were associated with leaf area, biomass dry mass and fresh mass, net photosynthetic rate, intercellular CO₂ concentration, stomatal conductance, transpiration rate of seedlings, Hill reaction, Mg²⁺-ATPase and Ca²⁺-ATPase activities, malondialdehyde and O₂^*-...

Using hyperspectral reflectance to detect changes in photosynthetic activity in Atractylodes chinensis leaves as a function of decreasing soil water content

J. LIU, Y. WANG, X.M. LIN, Z.C. XUE, F.R. ZENG

Photosynthetica 2024, 62(4):372-380 | DOI: 10.32615/ps.2024.040  

Application of hyperspectral reflectance technology to track changes in photosynthetic activity in Atractylodes chinensis (A. chinensis) remains underexplored. This study aimed to investigate the relationship between hyperspectral reflectance and photosynthetic activity in the leaves of A. chinensis in response to a decrease in soil water content. Results demonstrated that the reflectance in both the visible light and near-infrared bands increased in conjunction with reduced soil water content. The derived vegetable indices of photochemical reflection index (PRI) and the pigment-specific simple ratio of chlorophyll b...

Ascorbic acid is involved in melatonin-induced salinity tolerance of maize (Zea mays L.) by regulating antioxidant and photosynthetic capacities

M. ZHU, T. GUO, Y.B. LIU, R. XIAO, T. YU, J.X. HUANG, W.L. DU, X.M. ZHONG, B. SONG, F.H. LI

Photosynthetica 2024, 62(4):361-371 | DOI: 10.32615/ps.2024.039  

Melatonin (MT), an indole compound, can boost plant growth under abiotic stress conditions. This experiment aims to elucidate the synergistic effect of MT and ascorbic acid (AsA) in mitigating salinity stress by assessing the photosynthetic and antioxidant capacity of the maize inbred lines H123 and W961. The results indicated that exogenous MT and AsA significantly improved photosynthetic efficiency and biomass of maize under salinity stress. Additionally, exogenous MT and AsA also improved antioxidant enzyme activities, promoted regeneration of AsA and GSH, decreased reactive oxygen species contents, suppressed Na⁺ accumulation, and improved...

Hydraulic conductivity and photosynthetic capacity of seedlings of Coffea canephora genotypes

J.A. MACHADO FILHO, P.R. COSTA, L. DE O. ARANTES, S. DOUSSEAU-ARANTES, W.P. RODRIGUES, J. CRASQUE, E. CAMPOSTRINI

Photosynthetica 2024, 62(4):351-360 | DOI: 10.32615/ps.2024.031  

The aim was to investigate the morphological, photosynthetic, and hydraulic physiological characteristics of different genotypes of Coffea canephora under controlled cultivation conditions. Growth, conductance, and hydraulic conductivity of the root system of 16 C. canephora genotypes were evaluated in Experiment 1 (November 2013). In Experiment 2 (December 2014), in addition to the previous characteristics, gas exchange, photochemical efficiency, leaf water potential, and leaf hydraulic conductivity were investigated in five genotypes. No significant differences were observed in specific leaf hydraulic conductance, stomatal density,...

Effects of tillage methods on photosynthetic performance of different functional leaf groups of summer maize in coastal saline-alkali farmland

H.-X. LI, †, Y.-F. CHENG, J.-X. FENG, G.-L. FU, G.-L. LIU, P. LIU, H. REN, H.-Z. WANG, B. ZHAO, G. LI

Photosynthetica 2024, 62(4):339-350 | DOI: 10.32615/ps.2024.037  

This study aims to determine the changes in the photosynthetic performance of leaves at different leaf positions and their correlation and to screen out the basic tillage methods suitable for improving the yield. The decrease in soil salt content significantly improved the PSII performance index and quantum yield for electron transport of the bottom leaf group, synergistically enhanced the photosynthetic performance of summer maize leaves (especially the bottom leaf group), and enhanced the correlation between the bottom, middle (including the ear leaf), and upper leaf groups. Under subsoiling tillage conditions, the bottom leaves could produce more...

Honoring Hartmut Karl Lichtenthaler, innovative pioneer of photosynthesis, on his 90^th birthday

G. GOVINDJEE, T.D. SHARKEY, A. MELIS

Photosynthetica 2024, 62(4):326-338 | DOI: 10.32615/ps.2024.017  

We honor Professor Hartmut Karl Lichtenthaler, a versatile pioneer of photosynthesis research, plant physiology, isoprenoid biochemistry, and stress physiology of plants, for his groundbreaking and creative contributions to plant science. His innovative research on the chemical composition, ultrastructure, and function of chloroplasts and his detection of the major methylerythritol 4-phosphate (MEP) isoprenoid biosynthetic pathway in plants is key to our current understanding of the physiology and biochemistry of photosynthesis systems. His ingenious use of the powerful laser-induced chlorophyll a fluorescence imaging has helped us better understand...

On the discovery of the two-light effect on chlorophyll a fluorescence: Quenching of chlorophyll a fluorescence of Photosystem II by Photosystem I light

G. GOVINDJEE

Photosynthetica 2024, 62(3):302-304 | DOI: 10.32615/ps.2024.035