Stomatal Development During Leaf Expansion in Tobacco and Sunflower

Abstract

Changes in stomatal density and size were followed in tobacco and sunflower leaves expanding from 10% of final area (10% A_max) to A_max under different levels of radiation. Lower radiation increased final leaf area, reduced stomatal densities, and increased area per stoma but had little effect on stomatal area per unit leaf area at A_max. In very young leaves (20% A_max) there was a wide range in the sizes of individual stomata, some stomata being close to full size, but by A_max differences were small. The possible relationship between the developmental patterns described and photosynthesis is briefly discussed.