Photosynthetic rates in relation to leaf position in sunflower, (Helianthus annuus, L)

An experiment was conducted on sunflower (var. Morden) in pot culture to investigate the photosynthetic activity during different times of the day in leaves emerged from different nodes. Photosynthesis was measured using portable Infra-Red Gas Analyzer. Results revealed that peak of photosynthesis reached at 10.00 a.m. and declined in the afternoon in all the leaves. The older leaves besides having lower rate of photosynthesis continued to photosynthesize for a shorter duration as well.