Agronomic Evaluation of Soybean Genotypes Resistant to Iron Deficiency Chlorosis1

Abstract

Soybean [Glycine max (L.) Merr.] breeders are interested in the development of cultivars with high yield and resistance to iron deficiency chlorosis on calcareous soil. Our objective was to determine if there was a genotype × soil type interaction that would influence selection for yield on noncalcareous or calcareous soils among lines with a high level of resistance to iron chlorosis. Nineteen lines of Maturity Groups I and II with the best available level of resistance to iron chlorosis were evaluated on calcareous and noncalcareous soils at each of three locations in Iowa during 1979. Iron chelate applied to the plants permitted the evaluation of the genotype × soil type interaction in the absence of chlorosis symptoms.There was no genotype 4 soil type interaction for yield, maturity, height, lodging, seed weight, protein, or oil content. The rank correlation coefficient for mean yield of lines between calcareous and noncalcareous soils was 0.95. The top three lines for yield were the same on the two soil types. The results indicated that selection can be practiced for yield and other agronomic characters among lines resistant to iron chlorosis as effectively on noncalcareous as on calcareous soil.Significant yield reduction occurred on lines that showed slight yellowing in the absence of the iron treatment. This result indicated that complete elimination of yield loss due to iron chlorosis requires the use of cultivars or agronomic practices that prevent any chlorosis expression.