Fig. 4
Minimum (a—Fo) and maximum (b—Fm) fluorescence signal after 1 and 7 h in the imaging chamber for intact leaf material (black) and excised (grey) leaf tissue. From these values, the maximum PSII efficiency (c—Fv/Fm) was calculated. Subsequent measurements of maximum PSII efficiency in the light (Fv′/Fm′, d and e), PSII operating efficiency (Fq′/Fm′—f and g), the fraction of open PSII centres (qL—h and i) and non-photochemical quenching (NPQ—j and k) were calculated in response to increasing light intensity for excised (white circle) and intact (black circle) leaf material (n = 3–5) for 1 and 7 h after sampling. See Table 1 for full descriptions of chlorophyll fluorescence parameters. Asterisks indicate significant differences between excised and intact tissue, where ‘***’P < 0.001 ‘**’P < 0.01 ‘*’P < 0.05