ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Crop and Product Physiology
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1629432
Modified nutrient management protocol for optimum Biomass Production, Nutritional Quality, and Flavor-Related Phytochemical Properties of Hydroponic-Grown Kale (Brassica oleracea)
Provisionally accepted
- 1South Dakota State University, Brookings, SD, United States
- 2The Ohio State University, Columbus, United States
- 3USDA Agricultural Research Service,, Wooster Ohio, United States
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In hydroponic leafy green production, nutrient supply is not often based on crop-specific requirements. Our research has indicated that nitrogen demand is greater for kale (Brassica oleracea ‘Red Russian’) as compared to other leafy greens. Conventional nutrient management relies on a two-part water-soluble fertilizer system—Part A containing some macronutrients and micronutrients and Part B containing calcium nitrate (Ca(NO₃)2) —to maintain electrical conductivity (EC) at a desired level. However, optimizing nitrogen supplementation while maintaining crop quality remains a challenge in EC-based nutrient management. The current study evaluated the effects of enhanced nitrogen supplementation by changing the mixing protocol to using only calcium nitrate (Ca(NO₃)2) during the final week of production on the biomass, nutrient composition, and phytochemical properties of hydroponically grown kale. The results showed that Ca(NO₃)2-only treatment significantly improved shoot biomass, shoot-to-root ratio and uptake of total nitrogen, calcium, and magnesium by 28.5%, 22.1%, 46.0%, 27.5%, and 14.4%, respectively, as compared to conventional two-part nutrient adjustment. , indicating that nitrogen and calcium were key limiting factors for shoot growth. Despite the additional nitrogen supply, nitrate accumulation in kale shoots increased but remained within safe consumption limits. However, phytochemical analysis revealed reductions in total anthocyanins and vitamin C, while glucosinolate levels slightly increased. No significant effects were observed on photosynthetic properties, root growth, or acid and water usage. These findings highlight the potential benefits and trade-offs of targeted nitrogen supplementation in hydroponic kale production. Future studies should explore crop-specific nutrient management for enhancing both crop yield and nutritional quality for other leafy greens.
Keywords: Calcium nitrate, Hydroponics, nitrate accumulation, Nitrogen supplementation, nutrient imbalance, nutrient management
Received: 15 May 2025; Accepted: 05 Aug 2025.
Copyright: © 2025 Yang, Samarakoon and Altland. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Uttara Chandani Samarakoon, The Ohio State University, Columbus, United States
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