Studies on the Organic Acid Metabolism in the Germinating Stage of Rice Seeds.

Using seeds of three varieties both upland and lowland rice, non-volatile organic acids occurred in germinating stage under three germinating conditions on the water blotted paper, in water (Subdivided to 0.6 cm and 5 cm depth) and in vacuum were examined by paper-chromatography. 1) In the ungerminated seeds, oxalic, citric and malic acids were found in both embryo and endosperm of upland and lowland rice seeds, however, glycollic, α-ketoglutaric, lactic, succinic and fumaric acids were found with the passage of germination time. 2) From these facts, it is suppposed that the Krebs cycle occurs in germinating stage of rice seeds, both embryo and endosperm. 3) In embryo, the amount of malic acid is larger than citric acid, while citric acid is larger than malic acid in endosperm, however in embryo, in vacuum, citric acid is more abundant than malic acid before 36 hours of germination time, and at the 72 hours, for the first time, malic acid became much more than citric acid. 4. In vacuum, both sort and quantity of acids were less than in two other germinating conditions. 5. No remarkable differences were found between upland and lowland rice Seeds, and Uruchi translucent grain) and Mochi (non-translucent) types.