Effects of iron nutrients in sub-arctic horticulture

Susan A. Woods
Wed, 22 Apr 2026 17:56:54 PDT

When managing iron (Fe) nutrients in controlled environment agriculture (CEA) hydroponic systems at sub-arctic regions between latitudes 50 to 70 degrees north, it is important to understand how plants regulate Fe to maintain Fe homeostasis, which is important for the production of Fe proteins and photosynthesis processes. The research objectives of this study are as follows: 1) determine Fe nutrients that promote yearly cycles of high-quality crops, 2) examine the regulation of Fe between plant roots and vegetation, and 3) explore whether seasonal adjustments in Fe nutrients can promote Fe homeostasis and the production of high-quality crops. This study considers the use of ferrous sulfate-heptahydrate (FeSO4·7H2O), ferric citrate (Fe-Cit) and sodium hydrogen ferric diethylenetriamine pentaacetate (Fe-DTPA) in Rosie romaine lettuce. Results demonstrated how Fe-DTPA produced high-quality crops every season compared to FeSO4·7H2O and Fe-Cit. The Fe nutrients had different influences on Fe concentrations in lettuce roots and vegetation. From April to May 2019, high pH and light levels impacted lettuce production. Under Fe-deficient conditions, plants exhibited more Fe in vegetative portions than roots. From December 2020 to January 2021, low pH and the need for supplementary lighting slowed germination and growth. Plant weight decreased and plants exhibited more Fe in roots than vegetative portions. From July to September 2020, low pH and optimal sunlight produced high-quality lettuce and adequate Fe concentrations. Research demonstrated that seasonal adjustments in Fe nutrient management can promote high-quality crops and Fe homeostasis.