The Role of Adenosine Tri-Phosphate in the Ripening of Rice Plant : I. Changes in the content of adenisine tri-phosphate in the embryo, endosperm and bran of the developing rece kernel

Abstract

Changes in adenosine tri-phosphate (ATP) content in the embryo, endosperm and bran of kernel were investigated during the development of the rice kernel. ATP content between the ventral and dorsal portions of the rice kernel was also compared. The results are as follows. 1. Embryo: ATP content kept increasing during the whole ripening period, especially the ATP content per dry weight in the embryo was much higher than that in the endosperm. At harvesting time, the ratio of the weight of the embryo to that of the kernel was 6.9%, while the ATP content ratio was 39.3%. 2. Endosperm: ATP content increased during the development and had a peak l4daysafter heading when the translocation of starch to the kerncl was most actively. There after it decreased till harvest and the content at harvest time was very low. 3. Bran: The changes in ATP content were similar to those observed in the endosperm, but the content per dry weight was much higher than that in the endosperm. Also the content per dry weight was 4.7 times as high as that in the endosperm and 2.1 times that in the embryo 7 days after heading. 4. ATP content was always higher in the dcrsal portion of the kernel than in the ventral one over the ripening period. These results abovc mentioned showed that ATP played an important role in ripening of rice kernel.