(±)-Dihydrozeatin was tested for its cytokinin activities in several bioassays and compared with different cytokinins. Dihydrozeatin stimulates the growth of tobacco callus at the concentrations of 10^-10^M with the optimum at 10^M, shoot development on tobacco callus at 10^M with 2×10^M IAA, the germination of lettuce seeds at 10^-10^M, the growth of radish leaf at 5×10^-5×10^M, and the development of lateral buds in pea seedlings at 5×10^M. This cytokinin inhibits the elongation of pea stem segment and delays senescence in detached wheat leaves at 10^-10^M. Dihydrozeatin is less active than zeatin and N^6-(isopentenyl) adenine (2iP) in these bioassays used, but it is of stronger activity than kinetin in the growth of tobacco callus and radish leaf and less effective in the germination of lettuce seeeds and the retention of chlorophyll
