Abstract
AbstractThe effect of soil moisture content and evaporative demand on diurnal variations of leaf resistance to water vapor diffusion were studied at two heights in a soybean (Glycine max L. (Merr.)) canopy. Under soil moisture stress, leaf resistance to water‐vapor diffusion of middle leaves in the canopy increased approximately 2 hr earlier in the day and to a greater extent than the resistance of upper leaves. This indicated a preferential flow of water to upper leaves. It is speculated that the degree of out‐of‐phase change in leaf resistance under stress conditions is related to canopy density.Leaf resistances of middle leaves decreased at a slower rate under adequate soil water supply than under drier conditions. On days with low evaporative demand, leaf resistances of upper leaves tended to be less (0.8 sec/cm) under the low soil moisture than under the high soil moisture supply. The apparent reduction of stomatal activity in leaves under low evaporative demand and high soil moisture supply is believed related to the lack of development of a small leaf‐water deficit necessary for maximal stomatal opening.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
