Differential effects of water stress on respiration in the light in woody plants from wet and dry habitats

Abstract

Respiration in the light, dark respiration, and leaf water status were monitored once a day in leaves of woody plants as seedlings dried during 7- to 10-day periods. Light respiration was estimated from an electrical analogue model of the response of net photosynthesis to ambient CO₂ concentration and also by the rate of CO₂ evolution into CO₂-free air. Respiration in the light was found to increase with water stress in four dry-habitat species and to decrease with stress in four wet-habitat species. Dark respiration changes could not account for the different trends observed. When light respiration in dry-habitat plants under water stress was temporarily inhibited, net photosynthesis during recovery from water stress was reduced compared with controls for at least a week. This may indicate a protective role of light respiration in these plants when under water stress.