Relationship between date of anthesis and grain weight on the panicle of rice.

Diversity of the Rachis-Branching System in a Panicle in Japónica Rice

“…Such a recent trend to increase the sink capacity by increasing panicle size suggested the necessity of analysis of the rachis-branching system in the panicle in many varieties with broad genetic diversity. This is because the spikelets within a panicle show variation in ripening, growth pattern, priority to photoassimilate partitioning and final grain weight depending on the position, and because the ripening is better in the spikelet on a primary rachis-branch than that on a secondary rachis-branch, and also better in the spikelet in the upper part of panicle than in the lower part of panicle (I watsuki, 1931;N agato, 1941;N agato and Chaudhry, 1969;Chaudhry and Nagato, 1970; Sasahara et al, 1982;Hoshikawa et al, 1984;Nakamoto et al, 1988;Yamagishi et al, 1996;Yang et al, 2000). These studies indicated that a large panicle with a large number of spikelets is not directly related to high yield, and that the rachis-branching system in a panicle is an important factor for attaining high yield.…”