Drought Acclimation Effects on Gas Exchanges and Accumulation of Some Osmotic Solutes in Four Arachis Hypogaeu Genotypes

Abstract

Water stress has profound effects on biophysic and biochemical processes of plants. The effects on the metabolism are not the same, depending on rate development, intensity and duration of water deficit (1). According to (2) stress preconditioning alters the relationship between leaf water and turgor potentials, so that plants with a previous history of water stress show lower leaf water potential at zero turgor. It has also been considered that they lower the critical leaf water potential which induces stomatal closure (3). Osmotic adjustment is a widespread response to water deficits (4) and has been considered an important process to maintain stomatal conductance, photosynthesis, leaf turgor and growth under drought (5). Osmotic adjustment is achieved by the lowering of osmotic potential due to the accumulation of compatible solutes (4), namely free amino acids, carbohydrates (eg. polyols), inorganic cations and organic acids. The purpose of this study was to investigate the presence of osmotic adjustment and its consequences on photosynthetic metabolism in 4 cvs. of Arachis hypogaea subjected to water stress.