RAPID STOMATAL RESPONSE TO RED LIGHT IN Zea mays

Gas exchange techniques were employed to study responses of stomatal conductance to pulses of red and blue light in the grass, Zea mays. Zea mays exhibited conductance increases following brief (< 1 min) pulses of either red or blue light, in contrast to other species (e.g. Commelina communis; Assmann, 1988, Plant Physiol. 87, 226–231) that exhibit consistent conductance responses only to pulses of blue light. Red light pulses of 450 μmol m−2s−1 for x min or 225 μmol m−2s−1 for 2x min were used to probe the fluence dependence of the red light response. The red light‐stimulated conductance increase was constant for a given fluence, and increased with increasing total fluence. The conductance response to red light was larger in field grown plants (maximum growth irradiance ˜ 1600 μmol m‐2s−l) than in plants raised in growth chambers (maximum growth irradiance ˜ 150 μmol m−2s−1).