Abstract: Typical Japonica rice Liaojing294 and Yanfeng47 were used to analyze the dorsal vascular anatomical traits of caryopsis and its relation to grain quality traits on primary and secondary rachises at 4–22 days after flowering (DAF). The results indicated that the section of dorsal vascular bundle was all near ellipse and its area and short axis length changed as parabola along with development of caryopsis of these two varieties. Caryopsis weight reached the maximum value at 12 DAF for Liaojing 294 and at 10 DAF for Yanfeng 47, respectively. The long axis length showed a monotonic increaseranked as follows: grains on top primary rachis > grains on bottom primary rachis > grains on top secondary rachis > grains on bottom secondary rachis. And these values of Liaojing 294 were larger than those of Yanfeng 47 at the same grain position. There was significantly negative correlation of the section area of vascular bundle and its long axis length with chalky rice rate and chalkiness. A significantly positive correlation of the vascular section area, long axis length, short axis length, sieve tube width and vessel number with caryopsis dry weight, caryopsis plumpness and grain plumpness was identified. So, the structure of dorsal vascular bundle is considered as the important morphological and anatomical basis for the difference of rice chalkiness, caryopsis plumpness and other organic matter accumulation related characters. with caryopsis development and grain filling. The dorsal vascular bundle, that is composed of centered vessels and circumjacent sieve tubes, showed a shape trend of wide to thin from bottom to top. At the same DAF, the vascular section area, long axis length, short axis length, sieve tube width, vessel number, caryopsis volume and caryopsis dry weight of these two varieties were all

Key words: Japonica rice, Caryopsis, Vascular bundle, Chalkiness, Caryopsis plumpness