Abstract
The hereditary dwarf rice plant, belonging to the genotype aaBB, was studied in comparison with the normal type AABB with special reference to the coleoptile growth and growth-substances.
The results obtained by the common Avena test showed that, the amount of growth-substances formed in 2mm of the top of coleoptile is practically equal in both types at the first stage of germination. But during the growth of coleoptile, the amount of effective growth substances in the normal type gradually surpasses that in the dwarf, while at the stage of six days after the sowing practically no growth-substances are to be found in both types of coleoptile.
On the other hand, soaking the grains in the solution of heteroauxin for 34 hours before germination accelerates the growth of coleoptile in both types when its concentration is optimum (0.0025%). But either in lower or in higher concentration the growth of coleoptile is more or less depressed. The growth increment in optimal concentration compared with that remained in water, is clearly greater in dwarf than in normals. This may presumably have a connection with the difference in the amount of growth substances in types above mentioned.
