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Title: An Evaluation of the Chelating Agent EDDS for Marigold Production

Author
item Albano, Joseph

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2008
Publication Date: 7/1/2008
Citation: Albano, J.P. 2008. An Evaluation of the Chelating Agent EDDS for Marigold Production. HortScience. 43(4):1177.

Interpretive Summary:

Technical Abstract: Aminopolycarboxylic acid (APCA) ligands (chelating agents) like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are commonly used in soluble fertilizers to supply copper (Cu), iron (Fe), manganese (Mn), and/or zinc (Zn) to plants. The offsite runoff and contamination of surface waters with these chelating agents, however, is of increasing concern due to their ability to remobilize heavy metals in sediments and their low susceptibility to biodegradation. The APAC, ethylenediaminedisuccinic acid (EDDS) is a structural isomer of EDTA that is biodegradable. Little information has been published, however, on the use of EDDS as a chelating agent in fertilizers for horticultural crop production. Therefore, a series of studies were conducted with the objective of evaluating FeEDDS as an Fe source for the production of marigold, to assess the capacity of EDDS to ex tract metals from commercial peat-based media, and to determine the vulnerability of FeEDDS to photodegradation. Marigold (Tagetes erecta L.) grown in peat-based media were fertilized with modified Hoagland’s solution containing 1 mg.L-1 Fe from FeEDDS, FeEDTA, or FeDTPA (Fe-chelate treatments). In all Fe-chelate treatments, Cu, Mn, and Zn were supplied as EDTA chelates. There was no significant difference in foliar Fe or Mn between Fe-chelate treatments, averaging 140 µg.g-1 and 88 µg.g-1, respectively. Foliar Cu and Zn, however, were significantly higher by 23% in the FeEDTA treatment than in either FeEDDS or FeDTPA treatments, which were not significantly different. Media analysis using one-part substrate and two-part unbuffered 2, 4, or 6 mM EDDS or DTPA solution incubated for 15, 30, 45, or 60 minutes were performed. As a mean of all chelate concentrations and incubation times, EDDS extra cted significantly less Cu (43%), Fe (77%), Mn (53%), and Zn (38%) than DTPA from media. Like FeEDTA and FeDTPA, FeEDDS photodegraded when irradiated, rendering Fe insoluble.