Stomatal behaviour of tea (Camellia sinensis) in relation to environment.
Except in the 2- to 3-month annual dry season, stomatal conductance was principally determined by incident irradiance; it was independent of shoot water potential, vapour pressure deficit or rate of photosynthesis. Within the dry season, conductance remained unaffected by shoot water potential and vapour pressure deficit but became more closely related to the rate of photosynthesis. It is suggested that a factor, associated with climatic change at the beginning and end of the dry season, alters the sensitivity of the stomata towards one or other of the 2 principal mechanisms by which they respond to light. Two anomalous forms of stomatal behaviour were observed: a transient opening in the middle of the day and a temporary closure in the middle of the morning.