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treatment, gas exchange parameters, including the photosynthetic rate (P n ; μmol CO 2 m −2 ·s −1 ), stomatal conductance ( g S ; mmol m −2 ·s −1 ), intercellular CO 2 concentration ( C i ; μmol·mol −1 ), and transpiration rate ( E ; mmol H 2 O m −2 ·s −1

respiration rate decreased curvilinearly as active Fe decreased ( Fig. 4E–F ). Fig. 4. ( A ) CO 2 assimilation rate, ( B ) g S , ( C ) calculated intercellular CO 2 concentration, and ( D ) PSII quantum efficiency of leaves sampled at noon, and

than it was in ‘Pride of Ringwood’ at 36 to 39 °C ( P < 0.003) ( Fig. 1C ). Intercellular CO 2 concentrations (C i ) remained steady between ≈250 and 300 mol/air at most temperatures, but they were highly variable within cultivars at 15 °C. ‘Cascade

) on the newest developed mature leaves of each treatment. The range of PPFD was set at 5, 15, 25, 50, 100, 250, 500, and 750 μmol·m −2 ·s −1 using the Li-6400-02B light source. The CO 2 concentration was set at 380 μmol·mol −1 , the rate of air

obtained upon equilibration at 25 °C. The EL expressed as percent was calculated as Gas exchange measurements. Net photosynthesis (A CO2 ), stomatal conductance ( g s ), intercellular CO 2 concentration (C i ), and leaf temperature were

rate ( P N ), stomatal conductance ( g s ), the air CO 2 concentration ( C a ), and intercellular CO 2 concentration ( C i ). Water-use efficiency ( W UE ) was calculated as W UE = P N / E , and stomatal limitation ( L s ) was calculated as L s

manufacturer’s instructions. Determination of leaf gas exchange. Net photosynthetic rate ( P N ), g S , intercellular CO 2 concentration ( C i ), and transpiration rate ( E ) were measured on fully expanded leaves between 8:30 and 10:30 am using the

., 2006 ). Salinity may limit photosynthesis through induction of stomatal closure leading to a reduction in intercellular CO 2 concentration ( Brugnoli and Lauteri, 1991 ) and inhibition of non-stomatal factors such as chlorophyll synthesis

net photosynthesis decreased with both temperature and drought, the intercellular CO 2 concentration increased, both at increasing temperatures (for all drought levels) and at increasing levels of drought, except between field capacity (Ψ L = –0

exchange and chlorophyll fluorescence parameters were measured using a portable photosynthesis system (LI-6400 XT, LI-COR, Inc., Lincoln, NE). The P n , T r , g S , and intercellular CO 2 concentration ( C i ) were measured on the upper, third fully