Effectiveness of N,N′-Bis(2-hydroxy-5-methylbenzyl) ethylenediamine-N,N′-diacetic acid (HJB) to supply iron to dicot plants

Abstract

Iron chlorosis is commonly corrected by the application of EDDHA chelates, whose industrial synthesis produces o,oEDDHA together with a mixture of regioisomers and other unknown byproducts. HJB, an o,oEDDHA analogous, is a new chelating agent with a purer synthesis pathway than EDDHA. The HJB/Fe 3+ stability constant is intermediate between the racemic and meso o,oEDDHA/Fe 3+ stereoisomers. This work studied the efficacy of HJB as a Fe source in plant nutrition. No significant differences between o,oEDDHA/Fe 3+ , HJB/Fe 3+ and HBED/Fe 3+ were observed when they are used as substrates of the iron-chelate reductase of mild chlorotic cucumber plants. Chelates prepared with the stable isotope 57 Fe were used in both soil and hydroponic experiments. In the hydroponic experiment, nutrient solutions with low doses of chelates were renewed weekly. Soybean plants treated with o, oEDDHA/ 57 Fe 3+ recorded the highest results in biomass, SPAD index and Fe nutrition. In the soil experiment, chelates were added once at a rate of 2.5 mg Fe per kg of a calcareous soil. Soybean plants treated with HJB/ 57 Fe 3+ recorded a higher biomass and SPAD index in young leaves than the plants treated with o,oEDDHA/ 57 Fe 3+ ; however, 57 Fe and total Fe concentrations in leaves were lower. The results of both pot experiments are associated with a faster ability by o,oEDDHA to provide Fe to the plants and with a more continuous supply of Fe from HJB/Fe 3+ . HJB/ 57 Fe 3+ effectively alleviated the Fedeficiency chlorosis of soybean with a longer lasting effect than o,oEDDHA/ 57 Fe 3+ .

Effect of Fe:ligand ratios on hydroponic conditions and calcareous soil in Solanum lycopersicum L. and Glycine max L. fertilized with heptagluconate and gluconate

“…At 21 DAT, the remaining plant shoots in each pot and the roots were sampled and kept separated in six replicates per treatment. On completion of the experiments the soluble and available Fe, Mn, Zn, and Cu fractions in soil were determined in all the pots (six replications) by the extraction method proposed by Nadal et al . with water and DTPA solutions followed by the acidification with HNO 3 (65%, Merck) to 1%, analyzed by AAS.…”

Timing for a sustainable fertilisation of Glycine max by using HBED/Fe3+ and EDDHA/Fe3+ chelates

“…Recent studies on the agro‐chemical behaviour of HBED/Fe 3+ have revealed that it is as effective as o , o ‐EDDHA/Fe 3+ in maintaining Fe in soil solution up to 3 days . Moreover, HBED can provide Fe to chlorotic plants in hydroponic and soil cultures . A longer lasting effect of HBED/Fe 3+ than of o , o ‐EDDHA/Fe 3+ when applied to soybean grown in calcareous soil is also identified .…”

Novel chelating agents for iron, manganese, zinc, and copper mixed fertilisation in high pH soil‐less cultures

“…The effectiveness of o , o ‐EDDHA (ethylenediamine‐ N , N ′‐di(2‐hydroxyphenylacetic) acid and analogous Fe chelates in neutral and alkaline conditions is well known . The industrial synthesis of o , o ‐EDDHA yields also other regioisomers [ethylenediamine‐ N ‐(2‐hydroxyphenylacetic acid)‐ N ′‐(4‐hydroxyphenylacetic acid, ( o , p ‐EDDHA) and ethylenediamine‐ N , N ′‐di‐(4‐hydroxyphenylacetic) acid ( p , p ‐EDDHA)] and polycondensate by‐products in variable amounts that contribute to modifying the efficacy of Fe fertilisers .…”