Abstract
From the results of previous experiments that the growth of leaf blade, leaf sheath and internode of floating rice plant considerably increased with the rise of water level, the authors postulated that the rate of elongation of the organs may be closely related to the behaviour of carbohydrates and some related enzymes, i. e., amylase and invertase. As illustrated in Table 1, the rate of raising water level was 3 cm a day in the incresing period and that of lowering water level was 6 cm a day in the decreasing period, a day at the decreasing period respectively. Results obtained were as follows: 1) The level of sugar content in leaf blade, level of floating rice (Co. 64) and Norin No. 22, gradually decreased with the rise of water level, but it increased conversely with the fall of water level. However, floating rice maintained a higher level of sugar content than that of Norin No. 22, even when the water level rised. Another noticeable phenomenon caused by submerged condition on was a marked decrease in starch content of the leaf sheath and internode, but the starch gradually increased with the succeeding decrease of water level. Such relationship between carbohydrate content and water level may be explained by the fact that sugars move mainly to the active growing parts such as leaf bleaf sheath and inthrnode of floating rice keeping pace with the rise of water level. 2) Amylase activity per fresh weight in above mentioned parts of floating rice compared with that of Norin No. 22 was always higher under either ordinary or submerged condition. On the other hand, invertase showed a little higher activity in Norin No. 22 only under ordinary condition, but floating rice always tends to be higher than Norin No. 22 under submerged condition. Although the activity of amylase and invertase per protein-N basis decreased under submerged condition, floating rice had a higher activity than Norin No. 22. Moreover, amylase activity in the leaf sheath of floating rice was higher than any other organ irrespective of treatments. Summarizing the results mentioned above, floating rice had not only higher content of carbohydrate but also higher activities of amylase and invertase than those of Norin No. 22 under submerged condition. These evidence may suggest that there is the latent ability for the vigorous elongation of floating rice.
