Figure 2.

Chlorophyll fluorescence and stomatal resistance in control and cys1 transgenic plants during SO₂ fumigation. A, Upper, effective quantum yields (F_m' − F_s/F_m') in 3-week-old plants untreated or exposed to 1 μL L⁻¹ SO₂ (SO₂) for 3 or 8 h in the light. A, Lower, stomatal resistance (Stomatal Resist; S cm⁻¹), measured in the same plants after 3 or 8 h of 1 μL L⁻¹ SO₂. B, Quantum yields (F_m' − F_s/F_m') of 7-week-old plants untreated or exposed to 1 or 2 μL L⁻¹ SO₂ for 6 h in the light. Values for each experiment are means (with se bars) of five control and seven or eight transgenic plants, each with two independent measurements.