Abstract
More than eight polyphenols were found in the leaves of rice plant by paperchromatograph. The main four of them gave red color reaction, while the others developed yellow color by Arnow's reagent under alkalinity. The former four polyphenols seem to have ortho-dihydroxy phenyl in their constitutions. Relative quantities of these polyphenols in rice plant were studied in relation to growing stages, plant parts, amount of nitrogen fertilizer supplied, plant varieties and infection by certain diseases.
Polyphenol contents of the leaves of rice plants increased gradually with the growth of plants and reached maximum at the tillering stage.
Leaves showed higher contents of polyphenols than the other parts of rice plant such as leaf sheath, neck and basal part of culm. Larger quantities of polyphenols giving red color reaction by Arnow's reagent were found in general in the varieties resistant against rice blast than in the susceptible varieties. Quantity of some polyphenols in the Chinese varieties such as Dojinkyo and Sento differed from the Japanese varieties such as Aikoku, Asahi no. 1 and others. As the effect of the nutritional conditions on the polyphenol contents of rice plants, experimental results show that the more the nitrogen fertilizer given the less the polyphenol contents in the leaves.
Generally, the polyphenol contents in the leaves, especially certain polyphenols, increased when leaves were infected with rice blast or Helminthosporium leaf spot pathogens.