DIFFERENCES IN GROWTH AND TRANSLOCATION AFTER HEADING BETWEEN 2 STRAINS OF ORYZA-GLABERRIMA STEUD. AND 2 CULTIVARS OF ORYZA-SATIVA L

An experiment was designed to know the differences in growth and trans location between Oryza glaberrima Steud. and Oryza sativa L. Two strai ns of O, glaberrima and two cultivars of O. sativa were used. They wer e grown in pots and under flooding condition. Growth was recorded from before heading. At heading and thereafter every week, one plant of ea ch strain or cultivar was transferred into an assimilating chamber con trolled at 45klux and 30 degrees C and treated with (CO2)-C-13 for one hour. The plant was sampled after 48 hours. The C-13 ratio Of each pl ant part was determined. Heading period (days from the first panicle e mergence to 50% heading) was longer for O. glaberrima than O, sativa. The life span of leaves at the same position was shorter for O. glaber rima than O. sativa. O. glaberrima completed their dry matter accumula tion to panicles in earlier stage of ripening compared to O, sativa. T he C-13 ratio of the panicles of O, glaberrima was greatest one week a fter heading, and that of O. sativa was greatest 3 or 4 weeks after he ading. These results justify the facts that dry matter accumulation to panicles of O, glaberrima was great in the early stage and very littl e in the late stage of ripening, while that of O, sativa was great eve n in the late stage of ripening.