Figure 1.

Leaf-level gas exchange measurements in response to changing light intensities reveal fast and consistent stomatal movements in Brachypodium distachyon Bd21-3. (a) Experimental setup for measuring leaf-level gas exchange parameters related with CO₂ capture and H₂O vapor loss by clamping a leaf in an infrared gas analyser (IRGA) chamber with controlled environmental conditions. Gas exchange is measured in changing light conditions (1,000–100–1,000–0 PAR) inducing stomatal closure in response to decreasing light intensity/darkness and stomatal opening in response to increasing light intensity. (b) Relative stomatal conductance (Rel g _sw) during the light transitions (n = 120, normalised to highest g _sw observed). (c) Absolute stomatal conductance (g _sw) response to light transitions (in black, data from 120 individuals corrected by average leaf area of 0.64 cm² and in magenta data from a subset of 35 individuals corrected by individual leaf area). (d) Intrinsic water-use efficiency (iWUE) response to light transitions (1,000–100–1,000 PAR) (n = 120, calculated as A/g _sw). (e) One-phase decay exponential regression for the transition 1,000–100 PAR (n = 120). (f) One-phase association exponential regression for the transition 100–1,000 PAR (n = 120). (g) One-phase decay exponential regression for the transition 1,000–0 PAR (n = 120). R ², half-time (T _±50%) and rate constant (K) are indicated. Error bars = SD.