Stress Enhances Indole 3 - butyric Acid - induced Rooting in Bupleurum falcatum L . ( Saiko ) Root Culture

Ildole 3 butyric acid (IBA) at 8rng l i induced, vigorous rooting in Bupleurum falcatum L. (Saiko) root culture in B5 medium after about 2weeks, when it was added at the time when detached roots were transferred to fresh medium. The rooting activity markedly decreased with delay of IBA addition after root 2transplantation, and was hardly observed when IBA was added at the 7th day. Stresses such as drought or heat markedly promoted the rBAinduccd rooting. Methylviologen, which causes superoxide generation in cells, and hydrogen peroxide also strongly promoted the rooting. We also examined the effects of active oxygen scavengers. Supplementation of some sugars, thiotaurin and methionine caused the rooting time delayed in a concentrationdependent manner. Histidine suppressed rooting much more, but did not the elongative growth of transferred roots at that time. All these results suggest that active o~xygen species caused by stress are involved in the process of rooting with IBA.