Due to their greater development in comparison to plants grown in rhizoboxes, the photosynthetic activity was measured at 27 DAS only in plants grown in pots by means of an infrared gas analyzer LI-6800 (Li-COR Inc., Lincoln, Nebraska, USA). PSII Photosynthetic Efficiency (Fv′/Fm′), stomatal conductance, electron transport rate (ETR) and CO2 Net Assimilation (A) were determined following Murchie and Lawson (2013) (link).
The Fv′/Fm′ ratio was measured as an index of efficiency in energy harvesting by the oxidized (open) reaction centres of photosystem II (PSII) in the last developed leaf, where Fv′ and Fm′ represent variable and maximal fluorescence, respectively. As Fm′ includes minimal fluorescence (F0′) of a dark-adapted leaf, Fv′ is calculated as Fm′ – F0′. Dark adaptation was set with the use of a far-red light to excite photosystem I (PSI), thus forcing electrons to drain from PSII. Only a few seconds of far-red light are needed to obtain this effect. The fluorimeter provides a “dark pulse” routine used to determine F0′. Five Fv′/Fm′ records were registered for each leaf of each replicate.
Leaf area was assessed after plant harvest at the end of both rhizobox and pot trials, by means of the LI-3100C Area Meter (Li-COR Inc., Lincoln, Nebraska, USA). Shoot dry biomass was determined after oven-drying for 48 h at 105°C.
The Fv′/Fm′ ratio was measured as an index of efficiency in energy harvesting by the oxidized (open) reaction centres of photosystem II (PSII) in the last developed leaf, where Fv′ and Fm′ represent variable and maximal fluorescence, respectively. As Fm′ includes minimal fluorescence (F0′) of a dark-adapted leaf, Fv′ is calculated as Fm′ – F0′. Dark adaptation was set with the use of a far-red light to excite photosystem I (PSI), thus forcing electrons to drain from PSII. Only a few seconds of far-red light are needed to obtain this effect. The fluorimeter provides a “dark pulse” routine used to determine F0′. Five Fv′/Fm′ records were registered for each leaf of each replicate.
Leaf area was assessed after plant harvest at the end of both rhizobox and pot trials, by means of the LI-3100C Area Meter (Li-COR Inc., Lincoln, Nebraska, USA). Shoot dry biomass was determined after oven-drying for 48 h at 105°C.
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