Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media

Multiple studies have examined the use of chelates to correct pH-induced Fe chlorosis. Here we report the effects of three common chelates on prevention of Fe chlorosis in two sensitive species at high pH. Calibrachoa and soybean were grown in three media pH ranges (6.0 to 6.5, 7.0 to 7.2, and 7.6 t...

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Main Authors: Julie A. Hershkowitz, Mackenzie G. Dey, Royal Heins, Bruce Bugbee
Format: Article
Language:English
Published: American Society for Horticultural Science (ASHS) 2025-02-01
Series:HortScience
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Online Access:https://journals.ashs.org/hortsci/view/journals/hortsci/60/3/article-p404.xml
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author Julie A. Hershkowitz
Mackenzie G. Dey
Royal Heins
Bruce Bugbee
author_facet Julie A. Hershkowitz
Mackenzie G. Dey
Royal Heins
Bruce Bugbee
author_sort Julie A. Hershkowitz
collection DOAJ
description Multiple studies have examined the use of chelates to correct pH-induced Fe chlorosis. Here we report the effects of three common chelates on prevention of Fe chlorosis in two sensitive species at high pH. Calibrachoa and soybean were grown in three media pH ranges (6.0 to 6.5, 7.0 to 7.2, and 7.6 to 7.8) and supplied with 1 mg·L−1 Fe as Fe-EDTA, Fe-DTPA, or Fe-EDDHA through fertigation. Chelate effectiveness was quantified by chlorosis rating and dry mass. In Calibrachoa, all three chelates prevented chlorosis at media pH up to 6.5, but above pH 7.2 only Fe-EDDHA was effective. Dry mass decreased as pH increased, but the decrease was less within the Fe-EDDHA treatment. Fe-DTPA was intermediate. There is a wide range in cost: Fe-EDDHA is currently four times, and Fe-DTPA is two times, the cost of Fe-EDTA. Fe-EDDHA binds Fe to pH 9, Fe-DTPA binds to pH 7.5, and Fe-EDTA binds to pH 6.5. Consistent with the stability constants for each chelate, the lower-cost Fe-EDTA chelate was effective in preventing chlorosis in Calibrachoa at media pH below 6.5. We conclude that the additional expense of Fe-DTPA and Fe-EDDHA is only necessary for Calibrachoa when the pH is above 6.5. However, Fe-EDDHA consistently resulted in greater dry mass of soybeans than Fe-EDTA in all pH levels. This suggests that Fe-EDDHA might improve growth of some species, even at a pH below 6.5.
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publisher American Society for Horticultural Science (ASHS)
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spelling doaj-art-228c071fecc44d4ea165f1b7b6ca90fd2025-08-20T02:14:36ZengAmerican Society for Horticultural Science (ASHS)HortScience2327-98342025-02-01603https://doi.org/10.21273/HORTSCI17892-24Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless MediaJulie A. Hershkowitz0Mackenzie G. Dey1Royal Heins2Bruce Bugbee3Department of Plants, Soils, and Climate, Utah State UniversityDepartment of Plants, Soils, and Climate, Utah State UniversityDepartment of Plants, Soils, and Climate, Utah State UniversityDepartment of Plants, Soils, and Climate, Utah State UniversityMultiple studies have examined the use of chelates to correct pH-induced Fe chlorosis. Here we report the effects of three common chelates on prevention of Fe chlorosis in two sensitive species at high pH. Calibrachoa and soybean were grown in three media pH ranges (6.0 to 6.5, 7.0 to 7.2, and 7.6 to 7.8) and supplied with 1 mg·L−1 Fe as Fe-EDTA, Fe-DTPA, or Fe-EDDHA through fertigation. Chelate effectiveness was quantified by chlorosis rating and dry mass. In Calibrachoa, all three chelates prevented chlorosis at media pH up to 6.5, but above pH 7.2 only Fe-EDDHA was effective. Dry mass decreased as pH increased, but the decrease was less within the Fe-EDDHA treatment. Fe-DTPA was intermediate. There is a wide range in cost: Fe-EDDHA is currently four times, and Fe-DTPA is two times, the cost of Fe-EDTA. Fe-EDDHA binds Fe to pH 9, Fe-DTPA binds to pH 7.5, and Fe-EDTA binds to pH 6.5. Consistent with the stability constants for each chelate, the lower-cost Fe-EDTA chelate was effective in preventing chlorosis in Calibrachoa at media pH below 6.5. We conclude that the additional expense of Fe-DTPA and Fe-EDDHA is only necessary for Calibrachoa when the pH is above 6.5. However, Fe-EDDHA consistently resulted in greater dry mass of soybeans than Fe-EDTA in all pH levels. This suggests that Fe-EDDHA might improve growth of some species, even at a pH below 6.5.https://journals.ashs.org/hortsci/view/journals/hortsci/60/3/article-p404.xmlchelatescontrolled environment agriculturegreenhouse productioninterveinal chlorosisplant nutritionsoilless media
spellingShingle Julie A. Hershkowitz
Mackenzie G. Dey
Royal Heins
Bruce Bugbee
Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
HortScience
chelates
controlled environment agriculture
greenhouse production
interveinal chlorosis
plant nutrition
soilless media
title Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
title_full Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
title_fullStr Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
title_full_unstemmed Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
title_short Fertigation with Fe-EDTA, Fe-DTPA, and Fe-EDDHA Chelates to Prevent Iron Chlorosis of Sensitive Species in High-pH Soilless Media
title_sort fertigation with fe edta fe dtpa and fe eddha chelates to prevent iron chlorosis of sensitive species in high ph soilless media
topic chelates
controlled environment agriculture
greenhouse production
interveinal chlorosis
plant nutrition
soilless media
url https://journals.ashs.org/hortsci/view/journals/hortsci/60/3/article-p404.xml
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