AUXIN INDUCES STEM ELONGATION IN NONPRECOOLED AND PRECOOLED DEROOTED AND ROOTED TULIP BULBS

Treatment with 0.1% indole-3-acetic acid (IAA, auxin) in lanolin paste to the cut Surface of the top internode of nonprecooled and precooled derooted and rooted bulbs of tulip after decapitation promoted the en tire stem elongation. Application of 0.5% 2, 3, 5-triiodobenzoic acid (TIBA) in lanolin paste at the middle of the last internode after IAA treatment promoted the elongation of the half top of the last internod es, but inhibited the elongation of the lower half of the last interno de and other lower internodes. It is suggested that auxin controls the stem elongation in tulip and that neither flower bud nor roots are ne cessary for partial stem elongation in the presence of auxin.