<b>Studies on Stomatal Movement in Dolichus biflorus Linn. Fabaceae </b> Usually relative turgor changes which maintain osmotic gradients in the guard cells cause stomatal movements. In many species the dominant participation of K in stomatal movements was well established. Organic acids such as malate, citrate, glutamate and aspertate were reported to serve as counter ions of K in many species. Both oxidative phosphorylation and photo phosphorylation are potential energy sources. In earlier studies, the functional role of PS II were not clearly understood. Hence the present study is aimed to understand the role of PS II in guard cells of Dolicus biflorus Linn. a Fabaceae member. Influence of PS II electron acceptors and donors such as potassium ferricyanide, hydroxylamine hydrochloride, MnCl2, Sodium ascorbate, diphenyl carbazide, ATP, ADP, ATP MnCl2 and ADP MnCl2, MnCl2 NADP and Hydroxylamine hydrochloride NADP is studied to understand the role of photo system II on stomatal movements. Turgor changes, guard cells, stomata movements, organic acids, K ions, PS II, ATP, MnCl2 364-368 Issue-6 Volume-1 Dr.G.Meerabai | B.Koteswari