Abstract
1. Reliance wheat, a differential variety to wheat stem rust, often showed resistance and high susceptibilities to the same isolate of rust fungus. This makes determination of physiological races of Puccinia graminis difficult.
2. Varying reactions to the same isolate of the fungus was obtained in an inoculation test conducted on Reliance wheat grown in two different localities. In this test the race 21 of the rust fungus reacted to the Morioka grown wheat as type 0 without exception, but on the Konosu grown wheat it was mostly 4 with some 0. On race 56 the wheat from both sources reacted as type 4.
3. This varying reaction of Reliance wheat to P. graminis was believed to have been caused by the possible hybridization with some other varieties on the Konosu and unlikely to the physiological changes brought about to the wheat as a result of having it grown under different environmental condition of the locality.
4. When growing Reliance wheat to be used as differential variety extreme care is required in order that the variety identity is not lost.
5. Isolates of P. graminis obtained in Nagasaki and Kagoshima prefectures and tested in 1959-1962 belonged to race 21 which was in accord with the report Of YAMADA et al. (1961).
