Rapid evaluation of sorghum for aluminum tolerance

Two screening methods tested in this study were based on the observation that roots of freshly germinated seeds exhibit their relative tolerance to Al during the first 48 hours of growth. Sorghum (Sorghum bicolor L. Moench) varieties were evaluated using toxic/nontoxic soil pairs in petri dishes and toxic/nontoxic solution pairs in a flowing aqueous system. The soils had 0, 61, and 72% Al saturation and the solutions had 0, 1.85 and 3.70 M l^–1 Al from AlCl₃ and 0.25 mM l^–1 Ca from Ca(NO₃)₂. Relative root lengths in both systems correctly differentiated 13 genotypes of known Al tolerance into tolerant and intolerant groups. Twenty six other sorghums genotypes were also screened using genotypes of known Al reactions as checks. The soil with 72% Al saturation and the 1.85 M l^–1 Al solution gave the highest correlation between the two systems and both effectively arrayed sorghums of known and unknown tolerance. For routine screening the authors prefer the soil system for its simplicity, efficiency, and use of a natural growth medium.Journal paper 11637. Purdue University Agricultural Experiment Station, Lafayette, Indiana. Contribution from the Agronomy Department.