Abscisic acid in seed dovelopment and germination of carrot

Abstract

The levels of abscisic acid (ABA) in primary and secondary umbel seeds of carrots (Daucus carota L.) during development and maturation were determined by gas liquid chromatography and related to seed growth and germination. The level of ABA was high during development, reaching a maximum at 21-28 DAF, then declined sharply as seeds matured. The high content of endogenous ABA during development did not impair seed growth and germination; however, the germinability of both seed sources was completely blocked by exogenous 10-4 M ABA. This indicates that ABA might activate two specific mechanisms of action: one promotive during embryogenesis and another one inhibitory during remobilization. Nonetheless, the data demonstrated, for the first time in all umbelliferous crop, the endogenous level of ABA in developing seeds, and the effect of exogenously applied ABA on seed germination