Evaporation rate, leaf water potential and stomatal conductance in Lolium, Trifolium and Lysimachia in drying soil.
Swards of perennial ryegrass and white clover were grown in controlled-environment cabinets in soil that was allowed to dry. The evaporation rate during drying was varied by changing the humidity or the illumination; the fastest rates of evaporation were similar to those reported for field crops. Leaf water potential depended on soil water potential and was independent of the evaporation rate. Stomatal conductance depended on both the leaf water potential and the leaf-air vapour pressure difference, i.e. on both the soil water potential and the potential evaporation rate.