Photosynthetica, 2026 (vol. 64), issue 1
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 (Rday)....
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 (FV/FM) and the photochemical quantum yield of PSII (ΦPo), 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 FV/FM values and the actual ΦPo values. Special attention is focused on the fluorescence measurement procedures using the saturating single...
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 (PN), intrinsic water-use efficiency, and intercellular CO2 concentration remained unchanged between diploids and tetraploids. Under WD, both genotypes reduced PN and stomatal conductance by similar proportions; however, only diploids decreased leaf area...
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...
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....
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...