Heading behaviour of native japonica (GI) and Japanese varieties (GII) grown during 1910-1920s were thermo-sensitive, home bred varieties during 1930s (GIII) - 1950s (GIV) were photo-sensitive and semi-dwarf indica derived varieties released since 1971 (GV) were controlled by basic vegetative phase. Number of leaves on main culm was increased with varietal improvement and culm length was gradually shortened as variety improved. GV variety had the shortest plant height among the groups. The first internode length was about 30cm in all groups and difference of 2nd-4th internode length was caused shortening the culm length. Panicle length and diameter of panicle neck were shortened and became thinner as variety developed from GI to GIV, however, GV had longer panicle and thick panicle neck, respectively. Number of panicles/hill and straw weight/hill increased and became heavier as variety improve from GI to GIV but GV had moderate number of panicle/hill and relatively light straw weight. Number of spikelet/panicle has been reduced with varietal improvement but GV had the biggest number. Grain yield/hill also increased as variety improved, however, it was decreased as transplanting season postponed and GV had shown the most sensitive difference. Top dry matter weight at heading stage and at 20 days after heading (20 DAH) had no difference among the groups except GI which was the smallest. Average grain weight at 20 DAH was heavier in the order of GI > GII, GV > GIV > GIII. It had a little variation in GI & GII while that of other variety group showed significant decrease as transplanting delayed. Harvest index (HI) of GV was the highest at 54% for the earlier transplanting and GIII had the lowest HI. Difference of HI became conspicuous for the later transplanting, the varieties bred later had the lower HI when transplanting of rice delayed. At the earliest transplanting applied (May 15), the grain yield was higher in the order of GI > GIV > GIII > GII > GI, however, that of Tongil type variety (GV) was the lowest for the latest transplanting (June 29). Interrelationship among the agronomical characteristics and grain yield was discussed.