Aluminum Tolerance in Soybean: I. Genotypic Correlation and Repeatability of Solution Culture and Greenhouse Screening Methods
- K. A. Garland Campbell and
- T. E. Carter
Breeding for Al tolerance in soybean [Glycine max (L.) Merr.], has been hindered by confusion regarding screening methodology. This study was undertaken to determine the relationship between greenhouse and solution culture screening methods, using 12 diverse soybean genotypes. Greenhouse media consisted of a Goldsboro sandy loam (fine-loamy, siliceous, thermic Aquic Paledult) at 19% Al saturation and the same soil amended with Al2(SO4)3 to 55% Al saturation. Solution-culture media consisted of 0 or 11 μM Al2(SO4)3 added to 200 μM CaSO4 solutions. Traits measured were shoot dry weight in greenhouse pots and radical elongation rate in solution culture. Aluminum tolerance was detected with both screening methods; however, unlike previous studies, agreement between methods was good (rG = 0.81), indicating that the solution-culture screen does have some utility in plant breeding. The solution-culture screen had a higher repeatability (0.78, based on six replications, compared with 0.54 for the greenhouse), further substantiating its utility. Two factors were critical in establishing the relationship between the two screens: (i) expression of Al tolerance as a percentage of the control and (ii) abundant replication in the greenhouse. Reliance on growth in Al alone as a measure of tolerance led to poor agreement between methods in our study and is not recommended for breeding purposes, except where the genetic population is very uniform morphologically. Earlier published studies of Al tolerance in the greenhouse may have suffered from inadequate replication.
Copyright © 1990.