Stomatal Responses, Water Loss and CO2 Assimilation Rates of Plants in Contrasting Environments

Information concerning the simultaneous responses of stomata, water loss, and CO2 assimilation rates has not been reviewed for plants in natural environments.

Abstract

Stomatal apertures are the major pathway for the movement of CO2 from the atmosphere into the mesophyll of leaves. The presence of this pathway for the movement of gases also results in water loss from the hydrated surfaces within leaves to the atmosphere. Stomatal aperture appears to be controlled by complex mechanisms which operate to maintain a variable balance between allowing CO2 uptake to proceed, while restricting the loss of water vapor, and preventing leaf desiccation. Recent reviews have examined the physiological bases of stomatal function (Raschke 1979; Allaway and Milthorpe 1976) and stomatal responses to environment (Sheriff 1979; Burrows and Milthorpe 1976; Hall et al. 1976). Analyses which integrated stomatal effects on CO2 exchange, transpiration, and energy balance were developed based upon theory (Cowan 1977), which have led to hypotheses concerning optimal stomatal function (see Chap. 17, this Vol.; Cowan and Farquhar 1977). However, information concerning the simultaneous responses of stomata, water loss, and CO2 assimilation rates has not been reviewed for plants in natural environments.