Evaluation of Wild Oryza Species for Stem Rot (Sclerotium oryzae) Resistance. R. A. Figoni, Former Graduate Student, University of California, Davis 95616. J. N. Rutger, Research Geneticist, USDA, ARS, and R. K. Webster, Professor of Plant Pathology, University of California, Davis 95616. Plant Dis. 67:998-1000. Accepted for publication 8 March 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/PD-67-998.

Initial screening of 55 genotypes in 17 Oryza species and subsequent reevaluation of the 24 most resistant entries revealed that several species were significantly more resistant to stem rot than cultivated rice, O. sativa. Averaged over both experiments, 15 genotypes representing nine species were more stem rot-resistant than Colusa, the most resistant cultivar in California. In a test conducted on eight of the more resistant entries, the presence or absence of flowering had no overall effect on stem rot development. The best stem rot resistance was found in species with genomes different from cultivated rice; however, stem rot-resistant entries of three species, O. rufipogon, O. nivara, and O. spontanea, which carry the same genome as cultivated rice, were identified. These entries are expected to be useful donor parents for the interspecific transfer of stem rot resistance to cultivated rice.

Keyword(s): disease resistance.