Abstract
In order to determine the glume hair density, number of hairs located along outer glume edge were counted under an anatomical biocular microscope, for five grains in each variety, about 1251 cultivated rice varieties being collected from the world wide rice growing countries. Wide variations were observed in glume hair density, and the authors, therefore, classified them arbitrally into 7 classes according to the mean number of hairs, namely, none (below 5) rare (5-35) very small (35-50) small (50-60) medium (60-70) many (70-80) and heavy (over 80). The results were compiled in table 1. From this table we can see that in northern districts such as Japan, Korea, Manchuria and North China, U.S.S.R. and U.S.A., the modes appeared at the medium class, and some heavy class types were also found among them. On the contrary, in southern districts such as Central and South China, Formosa, India and Java, the modes lowered themselves to the small class and no heavy class varieties were found. A peculiar variation was found in the Phillippine varieties where most belonged to none or rare classes. Such glaberima types were also exceptionally found in the Japanese teratological varieties. It is generally concluded that the glume hair is denser and longer in the varieties which came from the northern countries than in those from southern countries.
