@article{oai:nara-edu.repo.nii.ac.jp:00008248,
 author = {石井, 滋規},
 issue = {2},
 journal = {奈良教育大学紀要. 自然科学},
 month = {Nov},
 note = {1. The rice plants planted nearly horizontally in paddy fields, began to exceed those vertically planted in the number of tillers about 15th day after transplantation; the rate of increase in the horizontal plot was especially remarkable in the late season culture. As the result, the number of ears in the horizontal plot was increased by 13% in the normal season culture, while it was up to 40% to 55% in the late season culture, with raising the number of non-productive tillers. 2. A detailed analysis on the rice stocks obtained from the above experiment showed that the horizontal plot surpassed the vertical in the ear number due to the increase of the primary tillers on the 3rd and 4th leaf nodes situated at the lower site of the stems, and the secondary tillers developed from them. According to the yield investigation on the normal season culture, the horizontal plot gained an advantage of 9% in the ear weight over the vertical. 3. When the axes of rice seedlings were inclined at angles of 60° to 90° from their vertical position, in the relatively small tiller buds on (n-4)-th and (n-5)-th leaf nodes situated at the lower site of the stems their growing was considerably accelerated, while in the larger tiller buds on the (n-2)-th or (n-3)-th node situated at the higher site their growing was retarded. This tendency in the growth of buds became marked with increasing inclination angle of the axes. But, the increase in its angle brought about an augmentation in inclination angle of leaf blades (the angle between a leaf and the axis) at the upper site and a remarkable retardation in the top growth. The effect of gravitational stimulation on the growth of tiller buds was more noticeable in seedlings with leaves excised than in intact ones. 4. Cultivation experiments showed that the seedlings horizontally transplanted were slowed down the elongation in plant height for a time, compared with those vertically transplanted, however, the difference of plant height hetween them was reduced with an occurrence of crooking up of the terrestrial parts in the former. Namely, in paddy field cultivations, their difference disappeared in 20 days at latest after transplantation, and in well-drained cultivations in pots, the plant height in the horizontal plot was recovered by 92% to 94% of that in the vertical plot on the 30th day. 5. In the seedlings of the horizontal plot, the leaf emergence rate, though being slow temporally, was hastened about 10 days after transplantation, and the emergence date of higher leaves became rather early than the vertical seedlings after the 14th day or so. The observation on the growing points of the seedlings kept horizontally for 10 days indicated that these facts resulted from the prompt differentiation of leaf primordia under the effect of gravitational stimulation. 6. In the seedlings which were putting forth the 9th leaf and cultivated in hydroponics for 6 to 9 days, a considerable elongation of the internode just beneath the 8th leaf node occurred in the horizontal plot, in which a marked geotropic reaction took place at the base of this internode, whereas its growth was not appreciable in the vertical seedlings. According to the histological observation, pith cells forming a file in this internode of the horizontal plot were a little larger in number on the lower side than on the upper, and even on the upper side, their number was about 2.8 times as large as that in the corresponding internode of the vertical plot. At the base of the internode in the horizontal plot, the cell length along the axis was apparently larger on the lower side than on the upper, being gradually diminished its difference towards the apical part. Thus, the cell length in the horizontal plot was, on an average, twice as large as the vertical. (to be continued)},
 pages = {39--71},
 title = {水稲の重力成形に関する作物学的研究(II)},
 volume = {26},
 year = {1977}
}