Evaluation of Lophopyrum elongatum as a Source of Genetic Diversity to Increase the Waterlogging Tolerance of Hexaploid Wheat (Triticum aestivum)

• Waterlogging tolerance and its physiological basis were evaluated in Lophopyrum elongatum (a species from a salt marsh habitat), Triticum aestivum (cv. Chinese Spring), their amphiploid, and disomic chromosome addition lines. • Growth in drained or waterlogged soil and aerated or deoxygenated stagnant nutrient solution were evaluated. Porosity, aerenchyma, rates of O2consumption, radial O2loss, and ethanolic fermentation in adventitious roots of selected genotypes were also measured. • L. elongatum was more tolerant of deoxygenated stagnant nutrient solution or waterlogged soil (0-48% reductions in growth, respectively) than 'Chinese Spring' (63-84% reductions), the amphiploid (49-81% reductions), or the addition lines (56-92% reductions). Roots of L. elongatum had a higher constitutive porosity than 'Chinese Spring', resulting in greater internal O2movement in these roots when intact plants were first transferred to an O2-free root medium. This trait, as well as the slower growth and development of L. elongatum, might have contributed to its greater waterlogging tolerance. • Despite the differences between L. elongatum and 'Chinese Spring' in some traits, none of the Lophopyrum × wheat lines showed substantial improvement in waterlogging tolerance.