Stomatal conductance and chlorophyll fluorescence in-field measurements were performed early in the morning. Stomatal conductance was determined by measuring the dynamic diffusion conductance of leaves using the portable AP4 porometer (DeltaT Devices Ltd., Cambridge, UK), in 5 replicates. Chlorophyll fluorescence was determined with the PAM2500 portable chlorophyll fluorometer (Heinz Walz GmbH, Effeltrich, Germany) equipped with LEDs for saturation pulses and blue and red actinic lights, a Leaf-Clip Holder 2030-B with an integrated micro-quantum sensor for recording the photosynthetic active radiation (PAR, in units of flux density μmol quanta/(m2·s)) and also temperature with a NiCr-Ni thermocouple. Hence, the measured PAR parameter is identical to PPFD (photosynthetic photon flux density). The effective photochemical quantum yield (Φ) of photosystem II was determined using the following equation: ΦPSII = (F′′m—Ft)/F′′m, where F′′m represents the maximal chlorophyll fluorescence yield when photosystem II reaction centers are closed by a strong light pulse, and Ft represents the continuously recorded fluorescence, according to the manufacturer. In photochemistry, the symbol Φ is reserved for quantum yield, according to IUPAC Recommendations [182 (link)], and represents the number of defined events which occur per absorbed photon.
Leaf clip holder 2030 b
Manufactured by Walz
Sourced in Germany
The Leaf-Clip Holder 2030-B is a device designed to securely hold leaf samples for laboratory measurements. It provides a stable platform to mount leaf samples for various analysis techniques.
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Lab products found in correlation
3 protocols using leaf clip holder 2030 b
1
Stomatal and Photosynthetic Assessment
2
Chlorophyll a Fluorescence in C. incanus
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Chlorophyll a fluorescence measurements were performed on attached young (Y), mature (M) and senescent (S) leaves of C. incanus using the Mini-Pam fluorometer (Walz, Germany) equipped with a leaf-clip holder (Leaf-Clip Holder 2030-B, Walz, Germany) which allows the simultaneous recording of the incident Photosynthetic Photon Flux Density (PPFD) on the leaf surface and abaxial leaf temperature. The maximal PSII photochemical efficiency (Fv/Fm) was measured in early morning on 30 min dark-adapted leaves [48 (link)]. For the quantum yield of PSII linear electron transport (ΦPSII) determination [49 (link)], the fluorescence measurements were conducted at midday under natural environmental conditions of PPFD of 800 ± (20) µmol photons m−2 s−1 and air temperature of 23 (±2) °C.
3
Chlorophyll Fluorescence Measurements
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Chlorophyll a (Chla) fluorescence was measured in the field using a portable modulated PAM-2500 fluorometer (Walz, Effeltrich, Germany), in four plants per species and timepoint. In dark-adapted leaves (30 min) the maximal Chla fluorescence (F m ) was induced with a saturating pulse (0.8 s duration, 8000 µmol m -2 s -1 intensity) while the initial fluorescence (F o ) was recorded with low measuring light intensities (ML<1 µmol photons m -2 s -1 , ML-frequency=200 Hz). The F v /F m was then estimated by the ratio
The operating quantum efficiency of PSII (ΦPSII) was measured by using the light clip of the PAM-2500 (Leaf-Clip Holder 2030-B, Walz GmbH, Effeltrich, Germany) In illuminated leaves (i.e. directly exposed to natural solar radiation) the operating quantum efficiency of PSII was estimated as ΦPSII=(F m '-F s )/ F m ', where F m ' is the maximal Chla fluorescence induced with a saturating pulse (0.8 s) and F s is the actual Chla fluorescence under illumination. During ΦPSII measurements, natural PPFD was recorded measured with the PAR sensor of the Leaf-Clip (Micro-Quantum-Sensor, Walz GmbH, Effeltrich, Germany) that was then used for ETR estimation. Actual PPFD ranged between 14 and 1541 µmol photons m -2 s -1 during the experiment.
The operating quantum efficiency of PSII (ΦPSII) was measured by using the light clip of the PAM-2500 (Leaf-Clip Holder 2030-B, Walz GmbH, Effeltrich, Germany) In illuminated leaves (i.e. directly exposed to natural solar radiation) the operating quantum efficiency of PSII was estimated as ΦPSII=(F m '-F s )/ F m ', where F m ' is the maximal Chla fluorescence induced with a saturating pulse (0.8 s) and F s is the actual Chla fluorescence under illumination. During ΦPSII measurements, natural PPFD was recorded measured with the PAR sensor of the Leaf-Clip (Micro-Quantum-Sensor, Walz GmbH, Effeltrich, Germany) that was then used for ETR estimation. Actual PPFD ranged between 14 and 1541 µmol photons m -2 s -1 during the experiment.
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