Fig. 5. Gross oxygen uptake (U_O) of attached leaves of wild‐type tomato (closed circles) and the hp‐1 mutant (open circles) during steady state photosynthesis at three different light intensities [850 (A), 400 (B) and 90 (C) µmol photons m^–2 s^–1] in relation to leaf water potential. Measurements were made in a closed gas exchange system using a mass spectrometric ¹⁶O₂/¹⁸O₂ isotope technique. For further details see Fig. 4.