Grain-filling Process in Waxy (Glutinous) Isogenic and Non-waxy Lines of Rice

Waxy (glutinous) and non-waxy isogenic lines of a rice cultivar, Taichung 65, which were established by TSAI and OKO (1965) after 17-time backcross recoveries of a hybrid with Taichung 65 (donor parent, a waxy variety, Kinoshita-mochi) were made available through the courtesy of the above two authors. In the present study, the waxy and non--waxy lines were compared with regard to the process of grain filling after anthesis. The materials were grown under four conditions each with two replications in a paddy field and a "vinyl-house" for two years. Heading date was recorded for each panicle, and the panicles were sampled to collect developing kernels. The number of kernels, and the fresh and dry weights of kernels were recorded. The grain-filling period was divided into. four stages. In the first stage (two weeks after anthesis), both water content and dry matter increased rapidly. In the second stage (the next two weeks), water content turned to decrease and dry matter deposited in the kernel increased rapidly, resulting in rapid decrease in percent water content. In the third stage (the following two weeks), water-content did not change much but dry matter increased slightly, percent water content decreasing gradually. The kernel attained the maximum dry weight at the end of this, stage. Thereafter, the kernel was naturally dried (the fourth stage).