Factors Inducing the Formation of Additional Vascular Bundles in Rice Coleoptile

[摘要] Rice coleoptiles usually have two vascular bundles, but grains occasionally have two, three, four or five bundles in some rice cultivars, such as ‘Tokyo-tozo-mochi'. The external or internal factors which affect the number of vascular bundles were investigated using ‘Tokyo-tozo-mochi', one of the Japonica upland rice cultivars. Plants were grown in the pots under natural conditions, then they were transfered into several environmental and cultural conditions within 10 days of 5 th to 15th day after flowering, because it is known that the additional vascular bundles are formed within this period. Among several environmental and cultural conditions, low air temperature (17/12°C, day/night) was most effective to induce the additional vascular bundles in coleoptile. Another set of plants was applied with several plant growth regulators such as ethyene, gibbereillin A3, inodole-3-acetic acid, benzyladenine, abscisic acid and brassinolides through leaf surface by foliar spray during the same period with that in the above experiments. Paclobutrazol (PP-333, inhibitors of gibberellin biosynthesis) was also given to plants through roots by soil application on the 5th day after flowring. Among plant growth regulators, gibbererillin A3 and benzyladenine were most effective as the inducer of additional vascular bundles. Low temperature may affect the formation of additional bundles through enhancing the endogenous level of plant hormones such as gibberellin.

[学科分类] 农业科学（综合）

[关键词] Additional vascular bundles;イネ;Coleoptile;維管束;Deepwater rice;浮稲;Gibberellin;鞘葉;Low temperature;植物生長調節物質;Plant growth regulator;ジベレリン;Rice;追加維管束;Vascular bundles;低温