Effects of Gibberellic Acid Treatment for Pollen Sterility Induction on the Physiological Activity and Endogenous Hormone Levels of the Seed in Safflower

In this research, our aim was to determine the effects of gibberellic acid, which was applied to safflower plants (Carthamus tinctorius L. cv. Dinçer 5-118) for pollen sterility induction, on some physiological activity and endogenous hormone levels of the seeds. Exogenously applied gibberellic acid (GA3) strongly influenced the endogenous hormone levels of the seeds by decreasing the levels of GA3 and zeatin, and increasing the levels of indole-3-acetic acid (IAA) and abscisic acid (ABA). The lowered endogenous GA3/ABA and zeatin/IAA ratios in the seeds significantly decreased the germination percentage and hypocotyl elongation, respectively. The seeds from GA3 treated plants had more hull percentage and less oil content than seeds from the non-GA3 treated plants. As a consequentce, it was indicated that poor germination and emergence vigor might be a major problem in hybrid safflower seeds produced from plants treated with gibberellic acid.