Evaluation of a simple method to screen soybean genotypes for salt tolerance

Excessive salt can reduce soybean yield [Glycine max (L.) Merr.] in grower fields. Salt-tolerant cultivars are needed to prevent field yield losses where excess salt is a problem. Soybean genotypes have primarily been evaluated for reaction to salt in the greenhouse using a labor-intensive and costly hydroponics method. A reliable, inexpensive method to screen soybean lines for salt tolerance would be useful in breeding programs. A simple, inexpensive method of exposing V2 to V3 plants growing in a sandy soil in plastic cone-tainers (PC method) was compared to the hydroponics method to evaluate soybean genotypes for salt tolerance in the greenhouse. Fourteen soybean genotypes including checks 'Hutcheson' (sensitive), and 'S-100' and 'Forrest' (tolerant) were exposed to 100 mM salt solution at the V2 to V3 growth stage. Genotypes responded similarly to the screening methods except leaf scorch, an indicator of salt damage, appeared up to 4 d sooner in the PC method. The PC method was highly correlated with the hydroponics method for leaf scorch score and chloride content in soybean leaves among the 14 genotypes evaluated. Exposure of roots at the V2 to V3 growth stage to salt solution using the PC method was less labor intensive, consumed less time, was less costly, and gave similar results compared with the hydroponics method. Thus, the PC method is an easy, reliable method to screen soybean genotypes for salt tolerance.