EFFECT OF SODIC WATER AND IRRIGATION ON SODIUM-LEVELS AND THE DEVELOPMENT OF EARLY LEAF-SPOT IN PEANUTS

Concentrations of sodium in plant tissues and soil, and the severity a nd incidence of early leaf spot (Cercospora arachidicola), were influe nced by water quality (sodic or nonsodic water) and method of irrigati on (sprinkle or trickle). Mean Na levels were always higher in tissues (leaf, stem, root, and seed) of plants receiving sprinkle-applied dee p-well water containing an average Na concentration of 220 mg L-1 and a sodium absorption ratio (SAR) of 103, than in plots receiving sprink le-applied shallow-well water containing an average Na concentration o f 4.8 mg L-1 and an SAR of 3.1. Na levels also were usually higher in tissues of sprinkle-irrigated than of trickle-irrigated plants. Na in root tissues generally was highest in sprinkle-irrigated plants receiv ing sodic water. Soil Na was higher in plots receiving sodic water; ir rigation method (sprinkle or trickle) did not influence soil Na. The i ncidence and severity (percentage of defoliation, diseased leaflets, a nd number of lesions per leaflet) of early leaf spot was usually great er in sprinkle-irrigated plants and in plants receiving sodic water. T he mean percentages of diseased leaflets, defoliation, and number of l esions per leaflet were 25, 60, and 35% greater, respectively, in plan ts receiving sodic irrigation water than in plants receiving nonsodic water.