Correlation of shoot and root growth and its role in selecting for aluminum tolerance in soybean

Abstract

Abstract Aluminum‐tolerant soybean cultivars are needed for deeper rooting and increased drought tolerance in acid subsoils. A major limitation in the development of such cultivars is Al‐screening methodology. Shoot growth is often used to infer root growth, but the genotypic relationships between root and shoot growth of older soybean plants have not been evaluated. Our objectives were (i) to test the hypothesis that shoot growth is a reliable indicator of acid soil (Al) tolerance in soybean, and (ii) to determine the relative Al tolerances of selected soybean genotypes. Nine genotypes were evaluated for Al tolerance by growing them for 37 days in greenhouse pots of unlimed (pH 4.3) and limed (pH 5.3) Tatum subsoil. Aluminum tolerance was determined by root and shoot growth and plant symptoms. Aluminum tolerance was detected using both shoot and root growth, and agreement between these two selection criteria was good. Genotypic correlations between root and shoot growth for unlimed soil, for limed soil, ...