Dual pam f

Slr0688i cells collected and resuspended with fresh BG11 (24 µg Chl mL⁻¹) were incubated with 100 µM pCMB for 1.5 h, 50 µM PMA for 0.5 h, or 10 mM GA for 0.5 h in the dark. Control samples were prepared by incubating cells with the respective solvents for the same time period. The samples were then injected into a 1 × 1 cm cuvette, and P700 absorption changes were measured with a fiber version DUAL-PAM/F (Walz) instrument, with the surface of the fiberoptics completely attached to the side of the cuvette. Measurements were performed in the remission mode, where measuring light (830/875 nm, intensity 10 with the DualPAM software) from the fiberoptics entered the cuvette and, after scattering and partial absorption by the cell suspension, was picked up by the fiberoptics from the same side. Changes in P700 absorption were measured by applying the multiple-turnover flash (300 ms, intensity of 16 with the software) following illumination for 10 s with FR light (720 nm, 2.7 µmol photons m^-2 s^-1, which was an intensity of 20 with the DualPAM software). Data collection was performed with Software Dual PAM Version 3.12(Windows 10); data analysis was performed with Microsoft Excel for Microsoft 365 MSO Version 2202.

Gas exchange was measured in a closed cuvette coupled to a mass spectrometer as described by Maxwell et al. (1998 ) and Dual-PAM/F (Heinz Walz) (Fig. S 1). Leaf discs (1.89 cm² area) were punched from the leaf and immediately placed within the chamber together with the wet filter paper supported on a mesh of equal area. The cuvette was first calibrated for oxygen and then flushed with nitrogen gas. Then, a known volume of CO₂ was added to create an atmosphere of approximately 4% CO₂ (high pCO₂) within the chamber; ¹⁸O₂ was injected to give an atmosphere of 18–21% O₂ and the signals were allowed to stabilise for 10 min. Gas consumption and leakage from the cuvette were negligible. The leaf was then illuminated at increasing irradiance from 50 to 2000 µmol photons m⁻² s⁻¹. The chamber temperature was maintained at 28 °C.

The chlorophyll fluorescence and P700 absorbance change around 830 nm were measured simultaneously using a Dual-PAM/F (Walz) with the intact leaves. A saturating pulse of red light (800 ms, >5000 μmol photons m⁻² s⁻¹) was applied to calculate several parameters. After measuring F_v/F_m and the maximal P700 absorbance change in the dark-adapted state, actinic light (red light) was used to irradiate the leaves. The intensity of actinic light was elevated from low to high levels in a stepwise manner. The methods used to calculate the quantum yields of PSII [Y (II), Y (NO), and Y (nonphotochemical quenching)] and photosystem I [Y (I), Y (ND), and Y (NA)] were as described (71 (link)).