Abstract
Starch grains have never been found in the root of rice plant except the root of seedlings cultured in upland seed beds, whereas many starch grains were observed in the root of rice seedlings sowed in lowland seed beds on Sept. 27. Starch accumulation mentioned above is considered to be caused by translocation from shoot into root of an excessive amounts of starch produced in shoot by photosynthesis beyond the quantity required for respiration in root which is depressed under low temperatures in autumn. According to the results of chemical analysis, starch contents in leaf and that in root are found amounting to 17.40 %, 20.24 % respectively, and as shown in table l that the seedling sowed in autum is rich in total sugar in leaf as compared with spring is very noticeable. Accumulating process of starch grains in root is shown by the microphotographs, Fig. 1 to Fig. 8, representing the transverse section of root of various ages stained with iodin-iodin potassium solution. First accumulation of starch grains in root takes place in the cortex parenchyma close around the central cylinder in root base, and then in epidermis and root tip. Size and quality of starch grains vary with the part of plant, viz the starch grains accumulated in root are of squarish shape and only about half the size of those in leaf sheath or culm, and look like those occurring in panicles.
