HIGH-FREQUENCY INDUCTION OF ADVENTITIOUS SHOOTS FROM HYPOCOTYL SEGMENTS OF LIQUIDAMBAR-STYRACIFLUA L BY THIDIAZURON

The effects of thidiazuron (TDZ) on adventitious bud and shoot formati on from hypocotyl segments of sweetgum (Liquidambar styraciflua) were tested alone and in combination with 2,4-dichlorophenoxyacetic acid (2 ,4-D). The combination of 1 mg/l TDZ with 0.01 mg/l 2,4-D resulted in the highest frequency of bud production. Lower concentrations of TDZ s timulated shoot production, generating the most shoots at 0.1 mg/l TDZ with 0.01 mg/l of 2,4-D. Inhibition of shoot elongation by TDZ was ov ercome by transferring shoot cultures to a shoot proliferation medium lacking TDZ or containing naphthaleneacetic acid and benzyladenine in addition to TDZ. Shoot production in liquid culture was significantly greater than that in solid culture. Comparisons of in vitro and ex vit ro rooting of the adventitious shoots demonstrated that ex vitro rooti ng produced plants with faster growth rates and more extensive root sy stems.