Alternatives to conventional field evaluation for genetic selection for Fe‐efficiency of soybean

Abstract

Breeding for improved Fe‐efficiency of soybean [Glycine max (L.) Merrill] has resulted in the identification of genotypes that exhibit little or no chlorosis when grown on calcareous soils in Iowa. Continued selection for even greater levels of Fe‐efficiency would be desirable to obtain parent lines that could facilitate the incorporation of Fe‐efficiency into high‐yielding cultivars. Two methods have been identified for inducing chlorosis in genotypes that do not have adequate symptoms in conventional field tests on calcareous soils. One method is used with soybeans grown on calcareous soil in the field. The main stems of plants to be evaluated are cut off above the cotyledonary or unifoliolate nodes during early vegetative development. The symptoms on the new leaves produced by plants after they have been cut off are more severe than on the leaves that develop on plants that are not cut off. The second method is a nutrient solution system designed to allow the evaluation of Fe‐efficiency. A good relationship between genotypic ratings derived from nutrient solution and field testing has been found. The major advantage of this system is that the severity of chlorosis can be controlled through the manipulation of nutrient concentrations.

Key words:

• Glycine max (L.) Merrill
• plant breeding
• chlorosis resistance
• plant stress
• nutrient solution