Effect of brassinolide on the growth of lk seedlings. Growth profiles were recorded 3 d after the fourth internodes of 8-d-old lk seedlings were treated with solvent only (A), 1 ng brassinolide (B), 3.3 ng brassinolide (C), 10 ng brassinolide (D), and 33 ng of brassinolide (E). F, Wild-type seedling treated with solvent only. Bar represents 1 cm.