Response of Wheat Grain to ABA and Imbibition at Low Temperature

During after-ripening of wheat grains, embryo responsiveness to abscisic acid (ABA) decreases in parallel with the loss of grain dormancy. Dormant grains of Triticum aestivum L. line ‘Kitakei-1354’ that had lost almost half their dormancy due to chilling still respond to ABA like fully dormant grains. Imbibition a: low temperature appears to break the dormancy without change of embryo responsiveness to ABA. Gibberellin (GA) and ABA-regulated α-amylase synthesis of the embryos. This is amplified when the grains are imbibed at low temperature. Imbibition at low temperature appears to condition cells and tissues of the embryo for germination and α-amylase synthesis.