In order to find out the possibility of increasing the number of spikelets by changing transplanting date, this study was conducted at Suwon, Yuseong and Jinju in 1979 and 1980. Climatic consumption effect was different depending on location, year, and variety. Number of spikelets can be increased by changing transplanting date due to the decrease of climatic consumption index (C C I) during the reproductive stage. Transplanting date for higher yield and number of spikelets of Tongil was May 25 at Suwon, from May 25 to June 5 at Yuseong and June 5 at Jinju, and in the japonica, it was slightly earlier than that of Tongil in each location. Increasing the number of spikelets and grain yield by the effect of decrease in C C C during the reproductive stage should be considered the percentage of ripened grains.