The inheritance and geographical distribution of the phenol reaction in rice has been investigated intensively. On the other hand, in the case of barley, almost all of the varieties show positive reaction to phenol, and inheritance study of the trait has not yet been reported. We investigated the phenol reaction of ca. 5,000 barley varieties preserved at the Barley Germplasm Center of Okayama University to find about 30 varieties which show a negative reaction to the phenol. These varieties are mainly from Southwest Asia. The reaction of awn was sharpest at all parts of the plant including seeds. The positive reaction must be the prototype of barley, because Hordeum spontaneum, a possible ancestor of the cultivated barley, shows positive reaction. Inheritance and linkage studies were conducted using varieties with negative reaction and linkage testers with positive reaction. Phenol reaction was dominant and showed a clear 3:1 segregation ratio in the F2 populations, indicating the trait was controlled by a single dominant gene Ph(phenol reaction). Linkage study revealed that Ph was linked with four marker genes(three loci) on the chromosome 2 and independent of 13 other marker genes located on the chromosomes except chromosome 2. Ph may be a useful marker gene and an interesting material for molecular-biological studies.オオムギの芒ではフェノールを酸化する酵素の活性が強くが、極めて少数の品種では芒のフェノール着色が見られない。本研究では芒のフェノール着色反応の遺伝性を解析した。結果は次の通り。1）芒のフェノール着色反応は優性遺伝子ph（phenol reaction）によって支配されている。2）Phは第2染色体にe-Ph-liの順で配列している。3）芒、穀皮および果実（果皮）の反応が一致しない場合があるが、これが実験誤差か、それぞれの組織で別個の遺伝子が作用していることによるのかは確認を要する
