ARS | Publication request: Evaluation of a Simple Method to Screen Soybean Genotypes for Salt Tolerance

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 5, 2008
Publication Date: November 24, 2008
Citation: Lee, J., Smothers, S.L., Dunn, D., Villagarcia, M.R., Shumway, C.R.,Carter Jr, T.E., Shannon, G. Evaluation of a Simple Method to Screen Soybean Genotypes for Salt Tolerance. Crop Sci. 2008 48: 2194-2200.

Interpretive Summary: In the Mississippi Delta region of the South and in the coastal areas of the Carolinas, salt damage in soybean is a perennial problem. Salt builds up in the soil when soybean is rotated with paddy rice (as in the Delta) and when hurricane surges push brackish water onto prime agricultural land (as in the Carolinas). Once salt builds to harmful levels, no production practice which can remove salt from the field. Thus, the only viable farmer response in salt stricken fields is to grow varieties that are resistant to the salt that. In soybean, salt tolerant varieties have been identified in the past. However, most soybean varieties are not rated or screened for salt tolerance. As a result, farmers do not have good information to make variety selections in areas where salt is a problem. The stumbling block to getting this information out is that the screening methods for identifying salt tolerant cultivars are hard to use. The present paper describes an alternative short cut method for rating varieties as to their salt tolerance. Using this new method makes it possible to screen a much larger number of varieties than in the past and in a shorter time. This method is starting to be adopted by commercial breeders.

Technical Abstract: Excessive salt can reduce soybean yield 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-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-V3 growth stage. Genotypes responded similarly to the screening methods except leaf scorch, an indicator of salt damage, appeared up to four days 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-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 to the hydroponics method. Thus, the PC method is an easy, reliable method to screen soybean genotypes for salt tolerance.