Stomatal Conductivities in K‐Deficient Leaves of Maize (Zea mays, L.¹

Potassium deficiency, spraying with phenylmercuric acetate, and temporary “wilting” each caused varying degrees of stomatal closure in maize leaves. Concomitant decreases in photosynthesis and stomatal permeability were similar for all treatments. In normal air, viscous transfer of gas through stomata of these leaves was related to diffusive transfer of CO 2 in photosynthesis as predicted by theoretb cal and experimental observations of other workers. In CO 2 ‐enriched air, stomatal diffusive resistance of the leaves as calculated from photosynthesis rates, and stomatal viscous resistances as measured by a porometer, tended to be related differently in the case of K‐deficient leaves and previously wilted leaves as compared to the normal leaves. The data suggest these experimental treatments decreased the stomatal apertures and the capacity of the leaves to internally fix CO 2 . The latter phenomenon may be viewed as an increased internal diffusive resistance, which reacted serially with increased stomatal diffusive resistance and thereby resulted in marked decreases in CO 2 assimilation in treated leaves.