Figure 4.

Steady-state photosynthetic activity following rehydration of desiccated desert crusts. The crust was rehydrated for 5 min in the light and the level of the steady-state fluorescence, induced by 40 μmol photon m⁻² s⁻¹ of 650 nm light (L), was compared with that obtained from the same sample after addition of DCMU. Saturating white light pulses of 3,000 μmol photons m⁻² s⁻¹ were provided to reach Fm; D, dark.