Abstract
To clarify the translocation pattern of photosynthetic products, and the effects of crop growth rate (CGR) and reserve substances before heading on the dry matter accumulation in the panicle during the grain filling stage, we examined the dynamics of dry matter in Nipponbare (japonica), Zhongyou No. 3 (indica) and Shanyou 63 (hybrid rice variety) grown at the paddy field of Shinshu Univ. in Central Japan. The dry matter in the stover and panicle was divided into two fractions: 1) cellular contents (CC) that could be degraded by crude enzymes (a-amylase and protease) and, 2) cell wall materials (CW) that could not be degraded. The dry matter accumulation rate in the panicle part was related to CGR in the Nipponbare and Zhongyou No. 3, but to the rate of dry matter translocation from stover to panicle in Shanyou 63. The accumulation rate of CW in a stover was related to CGR in every variety. The time when the rate of translocation from stover to panicle was maximal was earliest in Nipponbare followed by Zhongyou No. 3 and Shanyou 63. The dominant stage of translocation from stover to panicle was later in Shanyou 63 and Zhongyou No. 3 than in Nipponbare. The dates when the panicle growth rate was maximal were earliest in Zhongyou No. 3, followed by Nipponbare and Shanyou 63. The rate of dry matter accumulation in the panicle during the early grain filling stage was lowest in Shanyou 63 among the varieties, and the dry matter accumulation rate in the panicle was higher in the late grain filling stage than in the early grain filling stage. Thus, Shanyou 63 was suggested to have a lower ability to degrade stored compounds in the stover or have a higher content of water soluble materials.
