Nature of the Resistance of Oat Varieties to Races of Oat Stem Rust

Abstract

WHETHER resistance of a given variety of plant to a given race of rust is based on a nutritional mechanism or on an inhibitory one seems still to be a debatable point. For example, is resistance due (a) to the inability of the rust fungus to obtain from the resistant host all the chemical precursors necessary for adequate nutrition, or is resistance due (b) to the presence of substances in and natural to the host or of substances arising from the interaction of the host and pathogen that directly or indirectly result in the inhibition of the pathogen ? The observations recorded here contribute somewhat to the elucidation of the mechanism of resistance.