Uptake, Movement, Activity, and Persistence of an Abscisic Acid Analog (8′ Acetylene ABA Methyl Ester) in Marigold and Tomato

Abstract

The abscisic acid (ABA) analog 8′ acetylene ABA methyl ester (PBI 429) was evaluated for its potential to alter the growth and moisture use of bedding plants during nursery production. Treating seedlings with the ABA analog as a root-dip slowed moisture use and growth of tomato seedlings under greenhouse conditions. In marigolds, comparable ABA analog treatments had no effect on growth and limited effects on plant moisture use. To determine whether these differences in response to treatment with the ABA analog were associated with differences in absorption of the analog and/or its persistence, the ABA analog was applied either as a foliar spray or root-dip, and the resulting concentrations of the ABA analog were monitored over a 10-day interval in both the roots and the leaves. In both crops, the ABA analog was detected in both leaf and root tissues irrespective of the mode of application, suggesting systemic movement of the analog. Tissue concentrations of the ABA analog were consistently lower in the foliar treatment than in the root-dip. The uptake and the retention of the ABA analog over time was similar in leaves of the two test crops, but less of the ABA analog was absorbed and retained in the roots of marigold plants than in the tomatoes. This suggests that the observed differences in responses of these two plant species to application of ABA analogs may be related to differences in retention or accumulation of ABA in the roots rather than to differences in the total amount of ABA analog absorbed or its movement and retention in the plant system. Levels of endogenous ABA were not significantly altered by application of the ABA analog.