Process of Dry Matter Accumulation into the Kernel and Grain Characteristics of Japonica and Indica Rice

[摘要] In order to confirm the process of dry matter accumulation into the Kernel, 20 panicles heading the even date were collected every day from 5 days after heading till maturity, and the spike-lets on the panicles were assorted according to the location on panicle into E, M, M' and L groups as in fig.4. The dry weight of each group collected every day was measured. The rsults obtained are summerized as follows: (1) In Tyukyo-Asahi, E. M, M' and L took 28, 30, 33 and 40 days to gain maximum dry-weight respectively, whereas 19, 20, 23 and 25 days were taken in Bluebonnet, as shown in fig.4. Indica varieties attained faster to mature stage and the disparity in days required to gain maximum dry-weight between E andL was less in comparison with japonica varieties. (table 1) Therefor, the divergence in moisture content among the kernels harvested in a field may be less in indicas and this character of indicas is considered to be more suitable for use of the combined-harvester and rapid drying of paddy. On the other hand, the competition for dry matter absorption among the kernels in a panicle will be harder in indicas for reason of short duration of dry matter absorption and large number of kernels per panicle. (2) In general, dry matter accumulation in rice kernels begins to concentrate 7-9 days after flowering at the central part of kernel and gradually spreads to the outer regions, and translucency follows the dry matter accumulation in the same order. (fig.1) At the time of the central part of kernel being translucent, indicas gained 33-35 per cent dry weight as compared to 25-28 per cent in japonicas. (fig.4, table 1) During translucency progressed from central part till 1/3 of lateral diameter on the transverse section of fully ripened kernel, indicas gathered 24-26 per cent weight, whereas japonicas gathered l5-19 per cent weight. During translucency spread from 1/3 of lateral diameter till 2/3 of lateral diameter, indicas got 21-24 per cent and japonicas got 25-29 per cent. After 2/3 stage, 20 per cent and 30 per cent was gained by indicas and japonicas respectively till fully ripened stage. The difference between indicas and japonicas in the process of dry matter accumulation is considered to be correlated with the difference of hardness (density of dry matter) distribution in the transverse section of kernel. (fig.7)

[学科分类] 农业科学（综合）