Abstract
About 2000 varieties of cultivated rice collected in the rice growing countries in the world, records of shooting date were taken at the Experimental Farm of the Kyushu University in Fukuoka, Japan. They were sawn late May, transplanted early July and reared under customary management. The results were compiled in table 1, 2 and 3. In table 1, 1938-1942, wide variations were found, the earliest July 20th and the latest Sep. 24th. They were classed into 5 groups very early, early, intermediate, late, very late. Varieties belonging to the very early group were found in Hokkaido, Manchuria, North China, U.S.S.R. that is, in the so-called high latitude districts and the very late ones appeared in Japan p-roper, central and south China Phillippine, and U.S.A. Many sarnples collected in the tropical and subtropical regions could not shoot or ripe under such climatological condition as in Fukuoka and died out as shown in table 2. In table 3 the fact is presented that late variety group completes their shooting behavior during vety short perid, while the other groups need longer time. The former is the fittest ecological type in the experimental farm condition.
