Studies on the Relation between Seasonal Changes of Carbohydrates Accumulated and the Ripening at the Stage of Generative Growth in Rice Plant

Abstract

This experiment was conducted from variety Norin 8, in 1956 as a part of "Studies on Analysis of the Mechanism of the Ripening of Rice Plant" under controlled light intensity and nitrogen supply before and after the heading time. The main result obtained from this experiment are as follows : 1) Judging from the changes of carbohydrates amoung each organs (leaf-blade, leaf-sheath, culm) as shown figure 1, found out the carbohydrates having important connection to the production of grain, depends upon the sugars and starch, main storing part of ones restricted in leaf-sheath and in culm. Inhibiting effect of the photosynthesis to the rice plant come to decreasing of starch-content (%) more speedy than the sugars does. 2) Relation between the change of the carbohydrates (total sugar+starch) in leaf-sheath and in culm and the ripening under natural conditions shown figure 2. In case of much N-fertilizer applied under natural condition, showing sudden decrease of carbohydrates at about 5 days before heading, course of this decreasing seems to be the consumption of carbohydrates to the elongation of upper-nodes of culms and of ears. 3) By inhibiting the intensity of the photosynthesis at 16-7 days before heading, showing the decrease of the accumulated carbohydrates affecting the accumulation of the ones at begining of the ripening. In one case, when the ripening process completed in eary period, resulting the lighter kernel weight per 1000 on account of uncomplete development of the floret along the ear and. decreased number of spikelets per ear. By the results of decreased power of accumulation, reaccumulation of the carbohydrates in the culm remain maximum among the plots (as illustrated in Fig. 2-2). 4) Shading of the plants during the period of 6-15 deys after heading resulting the covering of the lowering of the photosynthesis, much amount of the accumulated carbohydrates translocated to the ear at early stages, conditioning the poorly developed kernels and increased the uncompletely developed grains (Fig. 2-3). 5) Prohibiting the intensity of the photosynthesis during the 16-25 days after heading translocation of the carbohydrates to the ear almost accomplished, development of the grains delayed transitionary affectionated the increasing effects of poorly developed grains and lighter kernel weight per 1000 (Fig. 2-4). 6) Shading of the sunlight at the later period of the kernel growth, 26-35 days after heading no influences of the treatment to, the kernel-development was seen (Fig. 2-5). 7) Accumulating power of carbohydrates to the culms at the later stage of the ripening having the positive relation between the photosynthsesis power of rice-plant and accumulating ability of the carbohydrates to the ear, from the results, special attentions will be paid to the ratio hull-rice vs. straw weight. 8) Judging from these results obtained, the authors estimate the fitness of the accumulating power of carbohydrates to the seed-production about 28-29% both in much fertilizer and in less one under natural conditions.