Effects of Gibberellin and Abscisic Acid on Germination, Dormancy Induction as well as Acid and Alkalin Phosphatase Activity in Seed Embryo of Bread Wheat Cultivar, RL4137

Effects of Gibberellic Acid (GA) and Abscisic Acid (ABA) on dormant and after-ripened wheat seed, Cultivar RL4137, were studied. The aim of the study was to evaluate the effects of seed after-ripening in comparison with Gibberellin application on breaking of seed dormancy. Moreover, the effect of Abscisic Acid on dormancy induction was also evaluated. Acid and alkaline posphatase activity of seed embryo in dormancy release and induction was studied. Six weeks of after-ripening increased germination percentage and reduced dormancy levels. A hundred µmol of GA increased germination percentage equivalent to six weeks of after-ripening. As for ABA treatments, only higher concentrations (200 µmol) of this hormone were effective on dormancy induction in after-ripened seed. Dormancy induction following ABA treatment was equivalent to the seed dormancy at the fourth week of after-ripening. After-ripening increased acid phosphatase activity up to the third week, however, GA did not affect the activity of this enzyme. Unlike acid phosphatase, after-ripening reduced alkaline phosphatase activity and similar to acid phosphatase no GA effect was detected on activity of this enzyme. ABA only had negative effect on acid phosphatase activity and did not affect alkalin phosphatase activity. The results of this study suggested that after-ripening and gibberellins breaks seed dormancy in different ways. Likewise, the ABA role in dormancy induction is through a control of acid phosphastase activity.