Brassinolide and Homobrassinolide Promotion of Lamina Inclination of Rice Seedlings

Brassinolide, a new plant growth-promoting steroid lactone, and its synthetic analog, homobrassinolide, showed strong activity in stimulating the lamina inclination of rice plants at very low concentrations of 0.0005 and 0.005 μg/ml, respectively, whereas IAA showed only a weak effect on the lamina inclination at 50 μg/ml. Thus, the lamina inclination test is useful as a highly sensitive bioassay for brassinolide and related compounds.