New light on the importance of peristomatal transpiration

The purpose of this paper is to discuss in detail once again some controversial views on the stomatal control mechanism, because it is essential that a consistent, universally valid concept of plant water relations provides a basis for an understanding of the impact of air pollutants on plants. The reader is reminded of the original concept of peristomatal transpiration, and its central role in the stomatal control system is reinforced, i.e. its function as a sensory mechanism in the negative feedback loop of stomatal conductance. The described stomatal dysfunction subsequent to the exposure of ozone to Picea abies (L.) Karst, needles can be traced to a specific impairment of this sensory mechanism, and this demonstrates once again the paramount importance of peristomatal transpiration.