Precise Monitoring of Lettuce Functional Responses to Minimal Nutrient Supplementation Identifies Aquaponic System’s Nutrient Limitations and Their Time-Course

Evangelia Tsoumalakou, Eleni Mente, Konstantinos A. Kormas, Nikolaos Katsoulas, Nikolaos Vlahos, Panagiotis Kapsis and Efi Levizou ()
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Evangelia Tsoumalakou: Department of Agriculture Crop Production and Rural Environment, School of Agricultural Sciences, University of Thessaly, GR-38446 Volos, Greece
Eleni Mente: Department of Veterinary Medicine, Aristotle University of Thessaloniki, GR-54006 Thessaloniki, Greece
Konstantinos A. Kormas: Department of Ichthyology and Aquatic Environment, School of Agricultural Sciences, University of Thessaly, GR-38446 Volos, Greece
Nikolaos Katsoulas: Department of Agriculture Crop Production and Rural Environment, School of Agricultural Sciences, University of Thessaly, GR-38446 Volos, Greece
Nikolaos Vlahos: Department of Animal Production, Fisheries and Aquaculture, School of Agricultural Sciences, University of Patras, GR-30200 Patras, Greece
Panagiotis Kapsis: ATC Automation Systems, Nikomachou 42, GR-11631 Athens, Greece
Efi Levizou: Department of Agriculture Crop Production and Rural Environment, School of Agricultural Sciences, University of Thessaly, GR-38446 Volos, Greece

Agriculture, 2022, vol. 12, issue 8, 1-21

Abstract: In aquaponics, a closed-loop system which combines fish and crop production, essential nutrients for plant growth are often at sub-optimal concentrations. The aim of the present study was to identify system limitations and thoroughly examine the integrated response of its components to minimal external inputs, notably crop’s functional parameters, fish performance, and microorganism profile. Lettuce and red tilapia were co-cultivated under only Fe and Fe with K supplementation and their performance was evaluated against the control of no nutrient addition. Photosynthesis, the photosynthetic apparatus state, and efficiency, pigments, leaf elemental composition, and antioxidant activity of lettuce were monitored throughout the growth period, along with several parameters related to water quality, fish growth, plant productivity and bacterial community composition. Nutrient deficiency in control plants severely impacted gas exchange, PSII efficiency, and chlorophyll a content, from day 14 of the experiment, causing a significant increase in dissipation energy and signs of photoinhibition. Fe+K input resulted in 50% and two-fold increase in lettuce production compared with Fe and control groups respectively. Nutrient supplementation resulted in higher specific growth rate of tilapias, but did not affect root microbiota which was distinct from the water bacterial community. Collectively, the results emphasize the importance of monitoring crop’s functional responses for identifying the system’s limitations and designing effective nutrient management to sustain the reduced environmental footprint of aquaponics.

Keywords: aquaponics; lettuce; nutrient supplementation; photosynthesis; functional response; red tilapia; chlorophyll fluorescence; antioxidant activity; root microbiota (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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