Iron chlorosis in soybeans

Abstract

Iron chlorosis in soybeans, Glycine max (L.) Merr., is a major problem in many soils in the western Great Plains. Tolerance to chlorosis differs significantly within soybean cultivars. Therefore, the objectives of this study were (a) to determine the tolerance of soybean cultivars to chlorosis; and (b) to determine the relationship of nutrient concentrations in leaves and the degree of chlorosis. A randomized complete block design consisting of four replications with a factorial arrangement of treatments (2x5x2) was used in a greenhouse experiment to study the objectives. The main effects were soil types (Quinlan cl, pH 8.1 and McLain si cl, pH 7.3), cultivars (Essex, Crawford, York, Gail, and Forrest), and fertilizer rates (0 and 0.2 kg Fe ha^‐1). Chlorosis was more severe in all cultivars grown in Quinlan soil than in McLain soil. York and Forrest exhibited the most severe chlorosis in Quinlan soil while York was the most chlorotic in McLain soil. Essex exhibited the least chlorotic symptoms of the cultivars tested in both soils. Chlorophyll concentration in leaves was higher in Essex than in the other cultivars. There were no significant differences in Fe concentration of leaves among cultivars grown in both soils. Phosphorus in leaves of Forrest was significantly higher than in the other cultivars when grown in McLain soil. High Ca and Mn concentrations in leaves were usually associated with the most chlorotic cultivars. Other nutrient concentrations and micronutrient ratios varied among chlorotic and nonchlorotic cultivars.

Key words:

• Cultivars
• iron fertilization
• chlorophyll concentration
• nutrient concentrations and ratios