The Abscisic Acid Content of Citrus with Special Reference to Lemon

Free and conjugated abscisic acid (ABA) in the fruit peel offour species of citrus and their distribution in the variousreproductive organs of Citrus limon L. cv. Eureka during ontogenywere determined by an indirect enzyme-linked immunosorbent assay(ELISA). The different citrus species varied in free ABA (3-8g g dry wt.) and conjugated ABA (10-39 /xg gl dry wt.). In general,the amount of conjugated ABA was 4-fold that of free ABA. Inthe lemon flower, the combined style and stigma tissues containedthe predominant (>65%) amount of both free and conjugatedABA. During fruit development, free and conjugated ABA of thedifferent tissues showed dynamic changes. In the vesicles, freeABA showed progressive increases with development and reacheda high level at maturity whereas the conjugated ABA showed acorresponding decrease with fruit development. Free ABA in theseed increased with fruit development. The content of ABA incitrus fruit was significantly correlated ( = 8.06 + 2.81 Inx; /-2 = 0.84^**) with the weight of the fruit Key words: Abscisic acid, citrus species, reproductive organs, development