Sorghum genotypic differences in tolerance to excess manganese

Abstract

Manganese (Mn) toxicity can be a growth limiting constraint for many plants grown on acid soil. Plant species/genotypes tolerant to Mn could help overcome detrimental Mn toxicity effects on plants grown on high Mn soils. Thirty‐seven sorghum [Sorghum bicolor (L.) Moench] genotypes from a broad germplasm base were grown in solution culture (pH 4.5) with 0, 3.0, and 6.0 mM of added Mn above the basic solution concentration (18 μM) to determine genotypic differences in tolerance to excess Mn. Dry matter (DM) was used to evaluate 24‐day‐old plants (10 days in Mn treatments) for Mn toxicity responses. Wide variability among genotypes for differential DM was noted at 3.0 and 6.0 mM Mn. Sorghum generally tolerated high levels of Mn. Genotypes showing relatively high tolerance to excess Mn in solution were NB 9040, Wheatland, IS 7180, IS 7755, and IS 7809. Those genotypes showing relatively low tolerance to high Mn were ICA‐Nataima, Martin, IS 7173c (SC 283), IS 7321, IS 9187, IS 9785, and IS 9828. IS 7173c, an aluminum (Al)‐tolerant standard genotype, was sensitive to high Mn. Wide variability was noted among tissue culture generated lines derived from a common parent. Laboratory screening for tolerance to Mn toxicity was effective with sorghum, but results need to be verified in the field.