Abstract : An experiment was designed to know the differences in growth and translocation between Oryza glaberrima Steud. and Oryza sativa L. Two strains of O. glaberrima and two cultivars of O. sativa were used. They were grown in pots and under flooding condition. Growth was recorded from before heading. At heading and thereafter every week, one plant of each strain or cultivar was transferred into an assimilating chamber controlled at 45klux and 30'C and treated with 13C02 for one hour. The plant was sampled after 48 hours. The 13C ratio of each plant part was determined. Heading period (days from the first panicle 3mergence to 50% heading) was longer for O. glaberrima than O. sativa. The life span of leaves at the same position was shorter for O. glaberrima than O. sativa. O. glaberrima completed their dry matter accumulation to panicles in earlier stage of ripening 30mpared to O. sativa. The 13C ratio of the panicles of O. glaberrima was greatest one week after heading, and that of O. sativa was greatest 3 or 4 weeks after heading. These results justify the facts that dry matter accumulation to panicles of O. glaberrima was great in the early stage and very little in the late stage of ripening, while that of O. sativa was great even in the late stage of ripening.

Key words : Annual, 13C02, Oryza glaberrima, Oryza sativa, Percentage of reproductive tiller, Perennial, Translocation.