Effects of Auxin and Gibberellin on the Elongation of in vitro Pedicel Segments from Narcissus tazetta var. chinensis

Abstract:

The pedicel segments from Narcissus tazetta var. chinensis were treated with IAA and GA3 for 48 hours, and the length of the segment elongation was determined. The interactions between the two hormones were also discussed. Both 50 μ mol/L IAA and 30 μ mol/L GA₃ were found to promote the elongation of pedicel segments. Moreover, IAA performed more effectively than GA₃. Both 2,3,5-triiodobenzoic acid (TIBA) (an IAA polar transport inhibitor) at 200 μmol/L and uniconazole (S-3307) (a gibberellin biosynthesis inhibitor) at 65 μ mol/L significantly inhibited the elongation of pedicel segments. Following the 50 μ mol/L IAA treatment GA₁₊₃ content in the segments increased 3.4-fold as much as that in the control, whereas IAA content in the segments treated with 30 μmol/L GA₃ was slightly varied. It is suggested that IAA plays an important role in maintaining the level of active GA in pedicels and regulates the elongation of the pedicel segments together with GA.