Effects of Gibberellin on the Morphogenesis in Rice Plants : 6. Effects of gibberellin on the development of vascular bundles in panicles.

[摘要] 1. This study was carried out to make clear the effects of gibberellin upon the development of vascular bundles in rice panicles. 2. Gibberellin was applied to a variety of paddy rice "Sachikaze", at the concentration of 100 ppm mixed in nutrient solution, at the stage of panicle primordium differentiation. 3. It was cleared that the number of large vascular bundles in rachis and that of small ones in rachis and primary branches had been increased with the gibberellin treatment, though there had been no change in secondary branches and peduncles. 4. The increase of large and small vascular bundles in rachis was accompanied by the increase of primary branches, and the increase of small vascular bundles in primary branches was considered to be followed by that of secondary branches and peduncles. 5. The number of cells composing vascular bundle had been increased in both large and small vascular bundles at every portion with the treatment, and this tendency had been conspicuous acropetally to the distal region of primary branch. 6. Regarding to the number of cells in each element of vascular bundles, except parenchyma cells, the number of cells in every element, especially those of fibre and xylem vessels, had been increased by gibberellin. Sclerenchymatous cells could be foums remarkably not only in vascular bundle but also in the bundle sheath and the neighbourings. This tendency also had been conspicuous acropetally to the distal region of primary branch. 7. Based on the results previously obtained by the writers in which both the increase of spikelets in number and the occurrence of morphogenic abnormalities in spikelet were frequently found at the distal regions of panicle and primary branches, and on the results above mentioned, it was considered that the morphogenic effects of gibberellin on the panicle development should become conspicuous acropetally from base to tip in rice panicle.

[学科分类] 农业科学（综合）