Studies on White-Belly Rice Kernel : II. Location on the panicle on occurrence of white-belly kernel

[摘要] These studies in series wrere devoted to clarify the characteristics of white-belly kernel (those grains with opaque part at their ventral position of the endosperm) and to obtain the data on the development of the opaque part in rice grains. This paper described the relation between the appearance of white-belly kernel and the panicle character, the location on the panicle, the kernel weight and the kernel shape. The experimental materials used were Norin-8, Kinmaze and Koshihikari of Japonica type of variety and Koshen of Indica type of variety. 1. The occurrence of white-belly kernels was dependent on the number of the primary and the second-ary branches. White-belly kernels were increased with decreasing number of the primary and the secondary branches. The number of white-belly kernels in the upper branches were larger than those kernels in the lower branches. In the primary branches, many white-belly kernels were observed at the vigorous position except the head position, and in the secondary branches, many white-belly kernels appeared at the head position. On the other hand, Koshen, Indica type, showed the different pattern on the occurrence of white-belly kernels from Japonica type, i.e., the head position of the primary brdnches had also the white-belly kernels. 2. Negative corelations between numbers of white-belly kernels and numbers of ill-ripening kernels were observed. Positive corelations were observed between numbers of white-belly kernels and dry weight of kernels. 3. White-belly kernels in the upper position of the ramified primary branches had larger breadth and weight of grains than perfect kernels. But in lower ramified branches, the thickness and weight of white-belly kernels were less than those of perfect kernels. The white-belly kernels in the non-ramified lower branches had characteristics similar to those kernels in the upper branches. But, white-belly kernels at any position had higher ratio of width to thickness than perfect kernels. This means that white-belly kernels were flatter than perfect kernels. 4. Grains in the vigorous position showed the high increasing rate of dry weight growth at the early stage and the maximum rate was observed at the middle stage. On the other hand, weight of grains in the weak position was slowly increased with the development of the grain to the latter stage. Grains in the upper branches had the characteristics similar to ones in the vigorous position, and grains in the lower branches showed the resemblance with ones in the weak position. From these observations, the appearance of white-belly kernels might be caused by the unbaranced developing rate at the latter period during ripening as compared with the development at the early stage.

[学科分类] 农业科学（综合）