Influence of FeEDDS, FeEDTA, FeDTPA, FeEDDHA, and FeSO4 on Marigold Growth and Nutrition, and Substrate and Runoff Chemistry

Abstract

The objectives of the study were to determine effects of iron (Fe) source on plant growth, plant nutrition, substrate chemistry, and runoff chemistry. Iron source (FS) treatments consisted of Fe-aminopolycarboxylic acid (APCA) complexones iron ethylenediaminetetraacetic acid (FeEDTA), iron [S, S′]-ethylenediaminedisuccinic acid (FeEDDS), iron diethylenetriaminepentaacetic acid (FeDTPA), and iron ethylenediaminedi(o-hydroxyphenylacetic) acid (FeEDDHA) and non-chelated iron sulfate (FeSO4) added to a base nutrient solution at the rate of 1 mg·L−1 Fe final concentration. Marigold (Tagetes erecta) ‘First Lady' was grown in peat-based media fertilized with FS treatments over a period of 22 d. Iron source treatments were nonsignificant for foliar Fe, manganese (Mn), or zinc (Zn) averaging 162 μg·g−1 Fe, 228 μg·g−1 Mn, and 35 μg·g−1 Zn but were significant for foliar copper (Cu). Main effect of FS on pour-through (PT) leachate pH was statistically different but not practically significant, averaging 6.42. The FeDTPA treatment resulted in higher levels of Cu, Fe, and Zn in PT extracts. Leachate-runoff (LR) was collected and analyzed over the course of the study. Results of LR were similar to PT with levels of Cu, Fe, and Zn for the FeDTPA treatment resulting in higher concentrations of these metals. In both PT and LR, the highest concentration of Mn was associated with the FeEDTA treatment. Spectrophotometer analyses of PT and LR leachates determined the presence of all Fe chelates tested in those solutions.