To investigate the tolerance of barley genotypes to manganese-deficient calcarious soil on Eyre Peninsula.

• One hundred barley lines from a world collection were grown in plant breeders' plots (4 rows x 5 m) on a severely manganese-deficient soil.
• Only 10% of the lines showed good tolerance of manganese-deficient conditions, which were severe enough to kill many of the entries in the tillering stage.
• Extreme sensitivity to manganese deficiency was shown by all progeny of CI3576, an introduction from Egypt, which has conferred considerable yield advantage and disease resistance on its progeny under more highly fertile conditions.
• In all, there were 20 lines from CI3576, including Corvette, and Galleon, a newly released high-yielding feed barley.
• At present, Galleon is not recommended for calcareous sands, pending further agronomic work on its manganese fertilizer requirements.
• The established variety Clipper and its relatives, and Forrest, were also sensitive to manganese deficiency. The tolerant lines fell into three genetically related groups, all of which had pedigrees going back to traditional English land races or their derivatives.