Variation in Some Structural, Biochemical and Gas Exchange Characteristics of Sun and Shade Leaves of Vernonia amygdalina

Light intensity has an influence on the photosynthetic capacity of a plant. The objective of this research was to investigate the variation in some structural, biochemical and gas exchange characteristics of sun and shade leaves of Vernonia amygdalina. Sun and shadeleaves were studied, and theirlight response parameters including light saturation point (LSP), light compensation point (LCP) and apparent quantum yield were estimated. Photosynthetic pigment were quantified spectrophotometrically. The stomatal density was determined using the nail polish method, and examined using light microscope. The result of this study proves that high light intensity influence gas exchange, stomatal density, leaf thickness and photosynthetic pigment of the studied plant. As the light intensity increases, Amax, LSP and LCP increases. There are significant differences between the light response characteristics, photosynthetic pigment and stomatal density of sun and shadeleaves (P<0.05). Statistically significant negative correlation (P<0.05) was achieved among stomatal density and transpiration rate(E). As stomatal density increases, E decreases. The result leads to a conclusion that sun leaves of Vernonia amygdalina contribute the highest assimilation rate to the plant than shade leaves. Also, the higher stomatal density of sun leaves provides water saving to the plant.