Both blue and red light stimulated stomatal opening in isolated epidermal strips of Gaillardia pulchclla, the former being more effective. The blue light response was KCN-sensitive, whereas red light response was KCN-insensitive. For blue light enhanced stomatal opening, the involvement of oxidative phosphorylation was necessary. NADH application also increased stomatal aperture, suggesting the involvement of a plasmalemma redox system and this stimulatory effect appeared more pronounced under blue light than under red light. Stomatal responses to SHAM revealed the importance of cyanide-resistant respiration for stomatal opening under blue and red light illumination. The implications of alternative respiration in overcoming adenylate (ADP) restriction of stomatal control are discussed.
