Rapid Changes in Transpiration in Banana Leaves

Abstract

Simultaneous measurements of photosynthesis, transpiration, stomatal opening, and leaf thickness were made on banana leaves before, during and after excision under various controlled conditions. Excising the leaf in dry air caused a sudden decrease in leaf thickness, an increase in stomatal opening and in the rates of photosynthesis and transpiration. Excising the leaf in saturated air or under water caused no change in leaf thickness but an increase in stomatal opening and rates of photosynthesis and transpiration. The leaf thickness response appeared not to be entirely explainable in terms of a rapidly developing water shortage. The stomatal responses could not be linked directly to either a water shortage or a release of tension in the vascular system. The photo-synthetic and transpirational responses appeared to be due to the stomatal responses.