Dependence upon Wavelength of Stomatal Movement in Epidermal Tissue of Senecio odoris

Abstract

The spectral dependence curve for maintenance of stomatal opening in isolated epidermal strips devoid of mesophyll obtained from leaves of S. odoris was determined. Optima were observed at 432 m[mu] and at 675 m[mu]. Stomata became narrower than could be measured in light from 525 to 580 m[mu]-The spectrum shows that photosynthesis of the guard cell chloroplasts is responsible for the maintenance of stomatal opening. The spectrum of stomatal movement and that of photophosphorylation in spinach chloroplasts were similar. 3(3,4-Dichlorophenyl)-1,1-dimethyl urea (DCMU) induced a complete closure of stomata at 10-5 [image] concentration.