Studies on the development of various parts of paddy rice plant of 1st crop in Okinawa. 2. Seasonal changes of starch content in leaf-sheath.

摘要

The following are the results of a research on the seasonal changes of starch contents in the sheaths of the main stem in accordance with the leaf order, of the first crop of rice in Okinawa. 1. The starch contents in the sheath, as shown in Fig. 1, changes regulally in accordance with the leaf order. The starch content is high in the 6th and 7th sheath, and is lowest in the 10th. Following 10th sheath, the content becomes gradually higher up to the 13th or 14th sheath. It is remarkably lowered in the 15th sheath. 2. Starch content in the sheath is higher in tillering stages and just before heading and becomes minimum in the ear formation period. In the period of rapid development of the ear, the increase of starch content in the sheath is lingered, and just after heading, it is rapidly decreased (Fig. 1). Therefore, there is close relation between the development of an organ and starch content in the sheath. That the starch content in the sheath is high in the tillering stage is contrary to the reports made so far, however, it is considered that it is due to the peculiarity of the first crop and the characteristics of "Taichu No. 65 ". 3. Starch content in each leave increases with the development of the sheath, and decreases with decaying. It does not contained in the deal leaf. The storage period of starch in leaves in longer in the upper order leaves of lith and up than in those lower than the 11th. 4. The relations of the elongation period of each sheath and beginning time and that of maximum storage of starch in each sheath, as shown in Fig. 2, are found to be as follows. Starch storage in the lower order leaves begins after the end of elongation period, and in the upper order leaves, except 15th leaf, it begins in the highest activity of elongation period. The time of maximum storage of starch in leaves of lower leaf order becomes gradually later as the order becomes upper, and in those of upper order, it becomes highest just before heading. 5. It is considered that starch stored temporalily in the lower order leaves is utilized for the development and growth of organs, and that in upper order leaves is utilized mainly for the maturity of grains.