Aluminum, manganese, and iron tolerance improves performance of wheat genotypes in waterlogged acidic soils

Waterlogging results in high shoot concentrations of iron (Fe), aluminum (Al), and manganese (Mn) in wheat grown in acidic soil. The verification of this observation in several acidic soils, development of screening techniques, and identification of genotypes differing in tolerance made it possible to test whether tolerance of ion toxicities improves performance of wheat in waterlogged acid soils. Six wheat varieties selected for tolerance/intolerance of Al, Mn, and Fe were grown in three acidic soils (pH(CaCl2) 4.1-4.3) with or without waterlogging for 40 d. In terms of relative shoot dry weight, Al-, Mn-, and Fe-tolerant genotypes tolerated waterlogging better, outperforming intolerant genotypes by 35%, 53%, and 32%, respectively, across the soils. The Al-tolerant genotype had up to 1.8-fold better root growth than the intolerant genotype under waterlogging. Waterlogging increased DTPA-extractable soil Mn (71%) and Fe (89%), and increased shoot Fe (up to 7.6-fold) and Al (up to 5.9-fold) for different genotypes and soils. The Al-tolerant genotype maintained lower tissue concentrations of Al as compared to intolerant genotypes during waterlogging. Waterlogging delayed crop development but distinctly less so in the tolerant than in the intolerant genotypes, thus jeopardizing the capacity of intolerant genotypes to produce yield in Mediterranean climates with dry finish of the season. Pyramiding multiple ion tolerances into current wheat varieties with desirable agronomic and quality characteristics to enhance their performance under waterlogged acid soils should be considered.