The Comparative Effects of Blue and Red Light on the Stomata ofAllium cepaL. andXanthium pennsylvanicum

Abstract

Stomatal responses to blue and red light were compared in leaves of Xanthium pennsylvanicum (which contain starch in their guard cells) and in onion leaves (which are devoid of starch). Blue light was found to be more effective than red in opening stomata in both species. However, a significant difference in the ratios of blue to red light required to produce equal stomatal opening was found between Xanthium pennsylvanicum and onion. It is concluded that blue light may promote stomatal opening by its effect on enzymes controlling the starch and soluble polysaccharide content of guard cells.