Improvement of salt and waterlogging tolerance in wheat: comparative physiology of Hordeum marinum-Triticum aestivum amphiploids with their H. marinum and wheat parents

Hordeum marinum Huds. is a waterlogging-tolerant halophyte that has been hybridised with bread wheat (Triticum aestivum L.) to produce an amphiploid containing both genomes. This study tested the hypothesis that traits associated with waterlogging and salinity tolerances would be expressed in H. marinum-wheat amphiploids. Four H. marinum accessions were used as parents to produce amphiploids with Chinese Spring wheat, and their responses to hypoxic and 200mM NaCl were evaluated. Relative growth rate (RGR) in the hypoxic-saline treatment was better maintained in the amphiploids (58-71% of controls) than in wheat (56% of control), but the amphiploids were more affected than H. marinum (68-97% of controls). In hypoxic-saline conditions, leaf Na+ concentrations in the amphiploids were lower than in wheat (30-41% lower) but were 39-47% higher than in the H. marinum parents. A strong barrier to radial oxygen loss formed in basal root zones under hypoxic conditions in two H. marinum accessions; this barrier was moderate in the amphiploids, absent in wheat, and was weaker for the hypoxic-saline treatment. Porosity of adventitious roots increased with the hypoxic treatments; values were 24-38% in H. marinum, 16-27% in the amphiploids and 16% in wheat. Overall, the amphiploids showed greater salt and waterlogging tolerances than wheat, demonstrating the expression of relevant traits from H. marinum in the amphiploids.