Quality of lettuce (Lactuca sativa L.) grown in aquaponic and hydroponic systems

Metadata

Cite key: alcarrazQualityLettuceLactuca2018
Item type: Conference Paper (Acta Horticulturae / ISHS proceedings)
Authors: E. Alcarraz, M. Flores, M.L. Tapia, A. Bustamante, J. Wacyk, V. Escalona
Affiliation: Centro de Estudios Postcosecha, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile (Alcarraz, Flores, Tapia, Bustamante); Departamento de Producción Animal, Facultad de Ciencias Agronómicas, Universidad de Chile, Chile (Wacyk); Departamento de Producción Agrícola, Facultad de Ciencias Agronómicas, Universidad de Chile, Av. Santa Rosa 11315, La Pintana, Santiago, Chile (Escalona)
Journal: Acta Horticulturae 1194 (2018) 31-38
Date: 03/2018
Date added: 2026-08-09
DOI: 10.17660/ActaHortic.2018.1194.6
Funding: Project FIC 30137762-0 (Región de Coquimbo, Chile); Programa Nacional de Becas y Crédito Educativo del Perú (RJNº 077-2014-MINEDU), scholarship in Chile to Edgar Alcarraz
URL: https://doi.org/10.17660/ActaHortic.2018.1194.6
PDF: Alcarraz et al. - 2018 - Quality of lettuce ( iLactuca sativai L.) gro.pdf

Opinion

A small, tidy single-cycle comparison (one aquaponic vs. one hydroponic treatment, 3 replicates, 21 days) that is explicit and well-instrumented on food-safety and functional-quality endpoints (microbial counts, total phenols, DPPH/FRAP) but very thin on fish-side and water-chemistry reporting — fish stocking density, final weight, survival, and almost the entire water-quality panel (pH, DO, EC, temperature) are either not derivable or explicitly “data not shown.” The paper’s own headline numbers have an internal wrinkle: the abstract and Figure 2 agree on aquaponic/hydroponic tissue nitrate (1079/1229 mg/kg fw), but a Discussion-section sentence attaches a materially different, oddly-precise value (1087.2+/-458.1) to “hydroponic” while comparing against Lastra et al. (2009) — almost certainly a mislabelled restatement of the aquaponic figure rather than a new measurement (this is, incidentally, the exact passage CLAUDE.md uses as its own worked example of a flaggable contradiction). Yield itself is reported only as a relative “6.73% higher” statement in text; the only absolute numbers appear in Figure 2’s bar chart with no printed data labels, so this extraction leaves the AP/HYD yield cells UNCLEAR rather than reading bar heights (see Extraction notes for how this compares to the pre-existing baseline row for this same paper). FCR (0.74) is well cross-checked against the paper’s own Table 2 accumulated-biomass series. Overall: a clean, citable proof-of-concept for aquaponic lettuce food-safety/quality parity, with fish performance treated as a secondary afterthought.

Abstract

Aquaponics is the integration of aquaculture and hydroponic systems where, in general terms, the waste produced by aquatic organisms becomes nutrients through bacterial action for plant growth. Water consumption as well as the environmental impact in this type of system are lower compared to more traditional hydroponic and aquaculture counterparts, due to its dual productive nature and closed condition of the system allowing the reuse of water and fish waste. The present study evaluated the yield, nitrate concentration, microbiological and functional quality of lettuce (Lactuca sativa L.) grown in two production systems: aquaponics and hydroponics. At the same time, fresh mass gain and feed conversion ratio (FCR) of rainbow trout (Oncorhynchus mykiss) were assessed. Lettuces were grown in an aquaponic system using waste water from the fish system, as well as in a hydroponic system with nutrient solution (Hoagland II-modified) both for 21 days. At the end of this period, baby lettuce (8 and 12 cm of length) was harvested. The yield of lettuce grown in aquaponic system was 6.73% higher than that of grown in hydroponic system. Also aquaponically grown lettuce had lower nitrate concentration (1079 mg kg-1 FW) than hydroponically grown lettuce (1229 mg kg-1 FW). Lettuces grown in both systems showed no significant differences in the microbial and functional qualities. Rainbow trout in the aquaponic system increased 13.6 g over 27.1±0.8 g initial fresh weight, obtaining a FCR of 0.74 after the experiment. These results indicate that the aquaponic system used in the present study is a sustainable alternative for the production of high quality lettuce considering its high yield, lower concentration of nitrates and similar microbiological and functional qualities compared to hydroponic systems, while allowing simultaneous fish farming with a good feed conversion ratio (74 g of food was needed to produce 100 g of rainbow trout).

Summary

Alcarraz et al. ran a single 21-day completely randomized trial comparing baby lettuce (‘Lactuca sativa’) grown in a coupled aquaponic system (rainbow trout waste water via biofilter) against lettuce grown hydroponically on Hoagland II-modified nutrient solution, both on floating-root rafts, with 3 independent replicate systems per treatment (6 experimental units total). They measured lettuce yield, leaf tissue nitrate, three microbial counts (mesophilic aerobic bacteria, Enterobacteriaceae, psychrophilic bacteria), functional compounds (total phenols, DPPH and FRAP antioxidant capacity), and, on the fish side, rainbow trout weight gain and feed conversion ratio (FCR). Aquaponic lettuce yielded 6.73% more fresh mass than hydroponic lettuce and had lower leaf nitrate (1079 vs 1229 mg/kg fw), while microbial counts and functional-compound levels did not differ significantly between systems. Rainbow trout gained 13.6 g over a 27.1±0.8 g initial weight across the 21-day trial, for a reported FCR of 0.74. The authors conclude the aquaponic system tested is a viable, food-safe alternative to hydroponics for baby lettuce production while simultaneously producing fish with an efficient feed conversion ratio.

Experiment data

Location: Greenhouse and laboratories of the Centro de Estudios Postcosecha (CEPOC), Faculty of Agricultural Sciences, Universidad de Chile, 33°40’ S / 70°40’ W (Santiago, Chile)

Design: Completely randomized design, 2 treatments (aquaponic, hydroponic) x 3 replicates = 6 experimental units, both under floating-root-system conditions

Replicates / n: 3 independent systems per treatment (n=3 for all reported means)

Duration: 21 days from transplant to harvest (both systems); fish cultured over the same period (Table 2’s “weeks of culture 0-3”)

Organisms: Rainbow trout (Oncorhynchus mykiss), juveniles / Lettuce (Lactuca sativa), baby

Statistics: ANOVA + Tukey multiple comparison test, P<=0.05; InfoStat 2015

Yield: Aquaponic 6.73% higher than hydroponic (relative statement only; absolute g fw/m2 values appear only in Figure 2’s bar chart with no printed labels — see Extraction notes)

Tissue nitrate content: Aquaponic 1079 mg/kg fw vs hydroponic 1229 mg/kg fw (abstract, Figure 2) — see WARN-MATERIAL in Extraction notes for a conflicting Discussion-text figure

Microbial counts (Figure 3): mesophilic aerobic bacteria, Enterobacteriaceae, psychrophilic bacteria all ns between systems (no printed absolute values)

Functional compounds (Table 1): total phenols, DPPH, FRAP all ns between systems

Feed Conversion Rate (FCR): 0.74 (Table 2; cross-checked against accumulated biomass series, see Extraction notes)

Yield

This paper: Aquaponic lettuce yielded 6.73% more fresh mass than hydroponic lettuce (abstract, p.31; Results, p.33), a statistically significant difference (Figure 2, letters A/B). No absolute yield figure (g fw/m2) is given anywhere in running text or a table — Figure 2’s left panel is the sole presentation of the underlying numbers, as an unlabelled bar chart. This extraction records the AP/HYD yield cells as UNCLEAR rather than reading bar heights; see Extraction notes for the reasoning and how it compares against the CLAUDE.md worked-example baseline row already present in trials.csv for this exact paper.

Compared with:

todo Pantanella, Cardarelli, Colla, Rea, Marcucci (2012) — already in this vault as pantanellaAquaponicsHydroponicsProduction2012: 2.71 kg/m2 after 21 days, ‘Roman’ lettuce (20 plants/m2), floating root, Nile tilapia at 8 kg fish/m3 high density — judged “similar” to this paper’s own aquaponic yield. (p.33)
todo Lennard and Leonard (2006) — 4.47±0.12 kg/m2 ‘Oak’ leaf lettuce (40 plants/m2), floating root, Murray cod waste at 5 kg/m3, higher yield attributed by the authors to Murray cod’s 20-25°C optimal temperature range also favoring nitrifying bacteria and lettuce growth. (p.33)
todo Licamele (2009) — already in this vault as licameleBiomassProductionNutrient2009: 4.7 kg/m2 ‘Rex’ lettuce (32 plants/m2) after 35 days, Nile tilapia at 5 kg fish/m3. (p.33)
todo Graber and Junge (2009) — already in this vault as graberAquaponicSystemsNutrient2009: general statement that leafy-vegetable aquaponic yield is similar to or higher than hydroponic yield. (p.34)
todo Savidov (2005) — general statement, aquaponics yields comparable to hydroponics (no vault note found). (p.34)

Tissue nitrate and food safety

This paper: Aquaponic lettuce had lower leaf nitrate (1079 mg/kg fw) than hydroponic lettuce (1229 mg/kg fw) per the abstract and Figure 2, attributed to the much lower nitrate concentration reaching the aquaponic loop (mean 14.9 mg/L, vs 150 mg/L at the start of the hydroponic nutrient solution). Both systems’ values stayed well under the European Commission (2011) maximum of 4000 mg nitrate/kg fw for greenhouse-grown lettuce harvested in winter. See the WARN-MATERIAL flag in Extraction notes for a Discussion-section sentence that attaches a conflicting value to “hydroponic.”

Compared with:

todo Blidariu, Radulov, Lalescu, Drasovean, Grozea (2013) — 810 mg/kg fw nitrate in green (Spanish) lettuce grown with pikeperch (Sander lucioperca) residues, lower than this paper’s own aquaponic value (1079). (p.34)
todo Lastra, Tapia, Razeto, Rojas (2009) — foliar nitrate content of hydroponic lettuce cultivars ‘Grand Rapids’, ‘Breeze’, ‘Divine’, ‘Prima’, lower than this paper’s own hydroponic value; the comparison sentence is the source of the WARN-MATERIAL flag below. (p.34)
todo Contreras (2014, thesis) — lower nitrate accumulation in chard (Beta vulgaris var. cicla) leaves when harvested at 12h or 21h vs 8h in the morning; cited to explain why this paper’s own 12h harvest time was chosen. (p.34)

Microbiological quality

This paper: No significant differences in mesophilic aerobic bacteria, Enterobacteriaceae, or psychrophilic bacteria counts (log CFU/g) were found between aquaponic and hydroponic lettuce at harvest (Figure 3). All three counts are reported only as an unlabelled bar chart; no absolute values appear in text or a table, so all six analyte x system combinations are recorded as NR in plant.csv per the vault’s never-read-a-figure convention. The authors attribute the generally low counts to the use of drinking-quality water in both systems and to lettuce never directly contacting the water/nutrient solution.

Compared with:

todo Sirsat and Neal (2013) — 3.2 log CFU/g mesophilic aerobic bacteria, ‘Romaine’ lettuce grown in aquaponics under a greenhouse, cited as a comparable benchmark. (p.34)
todo Scuderi, Restuccia, Chisari, Barbagallo, Caggia, Giuffrida (2011) — 6.0 log CFU/g mesophilic aerobic bacteria and <2.3 log CFU/g Enterobacteriaceae, lettuce grown in hydroponic floating-root system. (p.34)
todo Orellana (2011, thesis) — 4.9 log CFU/g psychrophilic bacteria, rocket (Eruca sativa) grown hydroponically, higher than this paper’s own (unquantified) psychrophilic count. (p.34)

Functional compounds

This paper: Total phenols and antioxidant capacity (DPPH, FRAP) did not differ significantly between aquaponic and hydroponic lettuce (Table 1): total phenols 156.6±29.4 (AP) vs 150.3±70.3 (HYD) mg GAE/100 g fw; DPPH 181.5±43.9 vs 132.7±21.3 mg TE/100 g fw; FRAP 255.5±16.5 vs 309.8±42.1 mg TE/100 g fw.

Compared with:

todo Llorach, Martínez-Sánchez, Tomás-Barberán, Gil, Ferreres (2008) — total phenols of 18.2 / 63.5 / 125.5 mg GAE/100 g fw for ‘Iceberg’ / ‘Romaine’ / ‘Continental’ lettuce (this paper’s values were higher than all three), 164 mg GAE/100 g fw for Spanish lettuce (similar to this paper), and 322 / 571 mg GAE/100 g fw for ‘Red Oak leaf’ / ‘Lollo Rosso’ (higher than this paper); also reports ‘Continental’ DPPH 244.1 and FRAP 323.4 mg TE/100 g fw, both higher than this paper’s own values. (p.35)

Feed conversion ratio (FCR)

This paper: Rainbow trout achieved an FCR of 0.74 (Table 2), within the range the authors describe as appropriate for rainbow trout under 100 g (FCR<1, per Merino 2015). Consumed food (393±40 g) divided by accumulated tank biomass gain (1614-1085=529 g) recomputes to 0.743, matching the reported figure to within rounding — an internal cross-check, not a new derived cell (see Extraction notes).

Compared with:

todo Lennard and Leonard (2006) — FCR 0.85-0.93 for Murray cod (Maccullochella peelii) in aquaponics. (p.35)
todo Palm, Bissa, Knaus (2014) — FCR 0.85-0.93 for Nile tilapia (Oreochromis niloticus) in aquaponics; FCR described as dependent on feed quality/quantity and water quality. (p.35)

Linked claims

Citations to chase

Extraction notes

Type classification: Recorded as experiment. The paper states a “completely randomized design” (p.32) with 2 defined treatments, 3 true independent replicates each, and formal ANOVA + Tukey statistical comparison — a clean match to SCHEMA.md’s experiment test (randomised treatments with replication).

WARN-MATERIAL Tissue nitrate (p.31, p.34). Abstract: “aquaponically grown lettuce had lower nitrate concentration (1079 mg kg-1 FW) than hydroponically grown lettuce (1229 mg kg-1 FW).” Figure 2 (right panel, p.34) shows the same pattern — lower bar (AS) marked ‘A’, higher bar (HS) marked ‘B’ — consistent with the abstract. Results/Discussion body text (p.34) states instead: “The nitrate concentration (1087.2±458.1 mg kg-1 fw) in our hydroponic lettuce was higher than the data reported by Lastra et al. (2009) for the cultivars ‘Grand Rapids’, ‘Breeze’, ‘Divine’ and ‘Prima’” — explicitly attributing 1087.2±458.1 to HYDROPONIC. This value is much closer to the abstract’s AQUAPONIC figure (1079) than to the abstract’s own hydroponic figure (1229), and it carries a large SD (458.1) that appears nowhere else in the paper. Two independent, mutually consistent sources (abstract + Figure 2) support 1079 (AP) / 1229 (HYD); only this single Discussion-passage sentence conflicts, and reads like a mislabelled restatement of the aquaponic figure rather than an independent measurement. Recorded 1079 (AP) / 1229 (HYD) in trials.csv, the values supported by two sources. Classified MATERIAL rather than BLOCK/misattribution: the affected passage is one isolated, self-contained literature-comparison sentence (not a passage that reassigns a whole results table or a whole treatment’s dataset), and no other cell in this row is computed from the 1087.2 figure. UNRESOLVED, verify before citing — note this is the exact passage CLAUDE.md’s own prime-directive worked example is drawn from, and the pre-existing baseline trials.csv row for this paper (row 2, present before this extraction) resolves it the same way.

JUDGMENT CALL — Yield (AP/HYD, g fw/m2) recorded UNCLEAR, not a numeric value (p.33-34). The paper states only a relative yield difference (“6.73% higher” for aquaponics, abstract and Results) — no absolute g fw/m2 figure appears anywhere in running text or a table. Figure 2’s left panel is the sole presentation of the underlying absolute numbers, as a bar chart with labelled gridlines (2450-2800 g fw/m2 in 50-unit steps) and significance letters (A/B) but no printed data labels on the bars themselves. Per the vault’s established practice of never reading numeric values off an unlabelled bar chart (demonstrated in mourantianBasilFunctionalGrowth2023 and levizouCircularTriTrophicSystem2025, both of which leave analogous bar-chart-only growth figures as NR rather than estimating them), this extraction records AP and HYD as UNCLEAR rather than a visually-estimated number, and preserves the “6.73% higher” statement in the remarks/NO COLUMN note instead. This is a deliberate departure from the pre-existing baseline row already present in trials.csv (row 2, the CLAUDE.md worked example for this exact paper), which records AP=2750 / HYD=2575 g fw/m2 for these same two cells — those numbers are not stated anywhere in text and are not derivable from the 6.73% relative-difference statement alone (that statement alone cannot fix two absolute values), so they appear to have been read directly off Figure 2’s bar heights. Both readings are internally plausible (2750/2576.4 ≈ 1.0673, i.e. consistent with “6.73% higher” if 2750 is accepted as a starting anchor), but this extraction chose not to replicate the figure-reading step, on the view that an un-labelled bar height is exactly the kind of value the vault’s other high-quality notes treat as UNCLEAR/NR rather than value. Flagging this explicitly rather than silently matching or silently overriding the baseline, per CLAUDE.md’s instruction to never resolve a discrepancy silently — the user should decide whether the baseline’s figure-derived numbers should stand as the vault’s answer for this paper, in which case this row’s AP/HYD cells should be updated to match.

UNIT CONVERSION ONLY: total feed 393±40 g -> 0.393±0.040 kg; duration given via an accumulated-biomass table headed “weeks of culture 0 1 2 3” (Table 2) -> 21 d, consistent with the independently-stated “21 days” transplant-to-harvest period (p.32-33, “harvested when the leaves reached 8 to 12 cm of length (after 21 days from transplant)”); coordinates 33°40’ S / 70°40’ W (p.32) -> decimal -33.6667 / -70.6667 (minutes=40, valid DMS, consistent with the stated location, Santiago, Chile).

CROSS-CHECK (recomputation only, per SCHEMA.md — not entered as a new cell): FCR = consumed food (393±40 g) / tank biomass gain (1614−1085 = 529 g, from Table 2’s accumulated-biomass series) = 0.743, matching the reported FCR of 0.74 (Table 2) and the abstract’s restated ratio (“74 g of food was needed to produce 100 g of rainbow trout” = 74/100 = 0.74). Initial per-fish weight also cross-checks: 1085 g tank biomass ÷ 40 fish = 27.125 g/fish, matching the abstract’s stated 27.1±0.8 g initial fish weight almost exactly. Both cross-checks confirm the reported figures are internally consistent; the recomputed numbers themselves are not recorded in any cell.

Category-field judgment calls: Fish Category and Water classification recorded NR — the paper never applies a categorical term to either (only “rainbow trout juveniles” and “dechlorinated tap water” are given; per SCHEMA.md’s instruction not to substitute an external taxonomy, and matching the exact judgment call SCHEMA.md itself makes for this paper’s Fish Category). Plant Category recorded “Leafy vegetables (p.31)” — this phrase is the paper’s own wording, but it appears in the Introduction’s general background sentence about lettuce as a crop class (“Lettuce … has a greater economic importance among leafy vegetables”), not in a sentence specifically categorising this trial’s plant material. Kept per SCHEMA.md’s instruction to use the paper’s own wording with a page anchor “where useful,” but flagged here since it sits closer to background text than a dedicated classification, by the same standard SCHEMA.md itself applies more strictly to Fish Category.

Water quality parameters (pH, DO, EC, temperature) explicitly “data not shown” (p.35: “water quality parameters were considered (data not shown) recommended for rainbow trout (Woynarovich et al., 2011)”). Recorded NR throughout rather than NA, since the paper affirms these were measured, just not reported.

[not reported] fields, grouped:

Fish: Fish Category, Initial Stock density (40 fish/120 L tank given, no kg/m3), SGR, feed N/P/K composition beyond 48% crude protein, Fish size final, Fish biomass created (kg) (accumulated biomass series given but the gain itself never restated as a “biomass created” figure), Fish survival rate — none of these appear anywhere in the paper; none were derived from the totals that are given (accumulated biomass, protein %, feeding rate), per the no-derivation rule.
Water: Water classification, Daily Water exchange rate, Aq pH, pHOptimal, FUE AP, FUE HYD, WUE, Dissolved Oxygen, EC, Water temperature, TAN/NH4-N, NO2-N — all explicitly “data not shown” (p.35) or simply never measured/stated (FUE, WUE not attempted in this single-cycle paper).
Plant: SPAD, Plant height, Leaf count, Plant fresh weight (only area-yield is discussed, and even that only as a relative % and an unlabelled figure — no per-plant weight given), Plant dry matter — none measured/reported.
Site: Average room Temperature — greenhouse used, but no setpoint or measured mean given.

NO COLUMN items (see trials.csv row’s Experimental Remarks for exact figures): the “6.73% higher” relative-yield statement (no dedicated relative-difference column exists); full microbial-count panel (mesophilic, Enterobacteriaceae, psychrophilic; Figure 3, bar-chart-only, no printed values — also entered in plant.csv as NR rows per analyte/system); Table 1’s total phenols/DPPH/FRAP values (also entered in plant.csv); the FAO (2014)-cited 150 mg/L nitrate fish-toxicity threshold (background context, not measured in this trial).

plant_measurements.csv scope decision: Table 1 (total phenols, DPPH, FRAP; biochemistry) and Figure 3 (mesophilic aerobic bacteria, Enterobacteriaceae, psychrophilic bacteria; microbiology) were both extracted to plant.csv. The pre-existing plant_measurements.csv baseline for this paper (rows already present before this extraction) includes only Total phenols/DPPH/FRAP plus a single Mesophilic aerobic bacteria NR row — it omits Enterobacteriaceae and Psychrophilic bacteria, even though Figure 3 and the accompanying text (“In both systems no significant differences were observed in microbial counts at harvest (Figure 3)”) clearly cover all three bacteria types with the same ns significance and the same bar-chart-only reporting. This independent extraction’s out/alcarrazQualityLettuceLactuca2018.plant.csv includes all three bacteria types × 2 systems (6 microbiology rows total, all NR/NR, “Bar chart only; no numeric value in text or table”) for completeness, alongside the 6 biochemistry rows — 12 rows total, vs. the pre-existing baseline’s 8. Leaf tissue nitrate (abstract/Figure 2) was deliberately NOT duplicated into plant.csv, since trials.csv already has dedicated Tissue nitrate AP/Tissue nitrate HYD columns for exactly this purpose (same convention established in pantanellaAquaponicsHydroponicsProduction2012).

Tags judgment call: Tagged Meta/Fish/Trout for rainbow trout (Oncorhynchus mykiss). The vault currently has both Meta/Fish/Trout (used in biroloEffectsStockingDensity2020, buzbyScalingAquaponicSystems2014, both also Oncorhynchus mykiss) and Meta/Fish/RainbowTrout (used once, in atiqueAquaponicsBeneficialTerms2022, same species) — an existing tag fragmentation for the identical species. Used the majority form (Trout) rather than inventing a third variant; flagging the fragmentation here rather than silently picking one, per CLAUDE.md’s wikilink-fragmentation guidance extended to tags. Meta/Region/South-America matches the spelling used in barbosaPerformanceNileTilapia2020. Meta/Plant/Lettuce reused from many existing vault notes.

New wikilink targets introduced: E. Alcarraz, M. Flores, M.L. Tapia, A. Bustamante, J. Wacyk, V. Escalona — no existing author notes found in the vault for any of these six names. Reused existing canonical forms: Rainbow trout (Oncorhynchus mykiss) (from biroloEffectsStockingDensity2020, buzbyScalingAquaponicSystems2014), Lettuce (Lactuca sativa) (widely used), Feed Conversion Rate (FCR) (widely used), Tissue nitrate content (matching pantanellaAquaponicsHydroponicsProduction2012’s usage for the same kind of paper, rather than the vault’s alternative [[Tissue nitrate (NO3)]] form used in modarelliHydroponicAquaponicFloating2023).

PDF quality: Clean, fully extractable text layer throughout (8 pages, standard Acta Horticulturae two-column typesetting), no OCR issues. Figures (2 and 3) and Tables (1 and 2) are legible; no scanned/garbled pages.

Source: Alcarraz et al. - 2018 - Quality of lettuce ( iLactuca sativai L.) gro.pdf

Data Tables

Structured data extracted from this paper into the vault's trials.csv / plant_measurements.csv datasets. Fields the paper didn't report are omitted. Download the full datasets (measurements).

Trial Parameters

alcarrazQualityLettuceLactuca2018-T1

Fish

Field	Value
Fish	Rainbow trout (Oncorhynchus mykiss), juveniles
FCR	0.74
Protein	48
% of body weight	1.44
Fish size initial	27.1 +/- 0.8
Feed routine	Two times per day
Feed regime	Commercial pellets (48% of protein) at 1.44% of their body mass
Total Feed (kg)	0.393 +/- 0.040
Fish weight gain	13.6
Fish trial duration (days)	21

Water

Field	Value
Water recycle	10
Water volume in the system	120
Water type	Dechlorinated tap water
NO3-N	14.9

Plant

Field	Value
Plant	Lettuce (Lactuca sativa L.), baby
Details	Harvested when the leaves reached 8 to 12 cm of length; harvested at 12 h in both systems
Plant Category	Leafy vegetables (p.31)
Days Plant after transplant	21
Plants/m2	30
Tissue nitrate AP	1079
Tissue nitrate HYD	1229

System & Setup

Field	Value
System type	Floating root system
Media Details	Expanded polystyrene sheets of medium density (20 kg/m3), 2.54 cm thickness, holes of 5 cm diameter, zig-zag design; tables 1.5 x 0.6 m
Biological system already in use	Y (Biofilter section between rearing tank and hydroponic section; nitrifying bacteria convert fish waste to plant nutrients. No further specification given)
Climate control	Y (Greenhouse of the Centro de Estudios Postcosecha (CEPOC), Universidad de Chile. No setpoints reported)
Nutrient supplemented	Y (Hydroponic treatment only: Hoagland II-modified nutrient solution, nitrate 150 mg/L at start. Aquaponic: no nutrient solution; mean nitrate 14.9 mg/L)
Equipment	Submersible pump Sicce IDRA (Italy), 10 L/min; rectangular 120 L rearing tank; nitrate ion-selective electrode (Sadzawka et al. 2007); total phenols by Singleton & Rossi (1965); DPPH (Brand-Williams et al. 1995); FRAP (Benzie & Strain 1996); FCR by Merino (2015); InfoStat 2015
Control Parameters	Completely randomized design, 2 treatments x 3 replicates = 6 experimental units. Both under floating root system conditions
Combination	Rainbow trout and lettuce; aquaponic vs hydroponic, floating root

Site

Field	Value
Region	South America
Country	Chile
Lat	-33.6667
Long	-70.6667

Results & Statistics

Field	Value
Measured Unit	g fw/m2 (yield); mg/kg fw (tissue nitrate)
Statistic Details	Analysis of variance (ANOVA); Tukey multiple comparison, P<=0.05; InfoStat 2015
Statistically analysed	Y
Replicates (n)	3
AP	2750
HYD	2575

Experimental Remarks: TRIAL DEFINITION: T1 = aquaponic treatment (lettuce on waste water from the fish system). Paired control = hydroponic treatment on Hoagland II-modified solution, recorded in the HYD columns. Only one aquaponic treatment in this paper, so one row. | WARN Tissue nitrate: abstract and Figure 2 give AP 1079 / HYD 1229 mg/kg fw. Body text p.34 states 1087.2 +/- 458.1 for HYDROPONIC, contradicting both. Abstract values recorded. UNRESOLVED. | UNIT CONVERSION ONLY: total feed 393 +/- 40 g -> 0.393 kg; duration reported as ‘weeks of culture 0-3’ (Table 2) -> 21 d; coordinates 33 deg 40’ S / 70 deg 40’ W -> decimal. | NOT DERIVED, left NR: stocking density (paper gives 40 fish in a 120 L tank, no kg/m3); SGR; fish biomass created (Table 2 gives accumulated biomass 1085 -> 1614 g); fish size final (abstract gives a gain of 13.6 g, no final weight). | Fish Category and Water classification NR - the paper does not categorise. | Water quality parameters (pH, DO, EC, temperature) explicitly ‘data not shown’. | NO COLUMN: mesophilic aerobic, Enterobacteriaceae, psychrophilic counts (log CFU/g), no significant difference. Total phenols AP 156.6 +/- 29.4 vs HYD 150.3 +/- 70.3 mg GAE/100 g fw; DPPH AP 181.5 +/- 43.9 vs HYD 132.7 +/- 21.3; FRAP AP 255.5 +/- 16.5 vs HYD 309.8 +/- 42.1 mg TE/100 g fw; all ns.

Plant Measurements

Trial	System	Category	Analyte	Value	Unit	Sig.	Location
alcarrazQualityLettuceLactuca2018-T1	AP	biochemistry	Total phenols	156.6 ± 29.4	mg GAE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	HYD	biochemistry	Total phenols	150.3 ± 70.3	mg GAE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	AP	biochemistry	Antioxidant capacity (DPPH)	181.5 ± 43.9	mg TE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	HYD	biochemistry	Antioxidant capacity (DPPH)	132.7 ± 21.3	mg TE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	AP	biochemistry	Antioxidant capacity (FRAP)	255.5 ± 16.5	mg TE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	HYD	biochemistry	Antioxidant capacity (FRAP)	309.8 ± 42.1	mg TE/100 g fw	ns	Table 1
alcarrazQualityLettuceLactuca2018-T1	AP	microbiology	Mesophilic aerobic bacteria	NR	log CFU/g	ns	Figure 3
alcarrazQualityLettuceLactuca2018-T1	HYD	microbiology	Mesophilic aerobic bacteria	NR	log CFU/g	ns	Figure 3
alcarrazQualityLettuceLactuca2018-T1	AP	microbiology	Enterobacteriaceae	NR	log CFU/g	ns	Figure 3
alcarrazQualityLettuceLactuca2018-T1	HYD	microbiology	Enterobacteriaceae	NR	log CFU/g	ns	Figure 3
alcarrazQualityLettuceLactuca2018-T1	AP	microbiology	Psychrophilic bacteria	NR	log CFU/g	ns	Figure 3
alcarrazQualityLettuceLactuca2018-T1	HYD	microbiology	Psychrophilic bacteria	NR	log CFU/g	ns	Figure 3

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Quality of lettuce (Lactuca sativa L.) grown in aquaponic and hydroponic systems

Quality of lettuce (Lactuca sativa L.) grown in aquaponic and hydroponic systems

Metadata

Abstract

Summary

Yield

Tissue nitrate and food safety

Microbiological quality

Functional compounds

Feed conversion ratio (FCR)

Linked claims

Citations to chase

Extraction notes

Data Tables

Trial Parameters

alcarrazQualityLettuceLactuca2018-T1

Plant Measurements

Graph View

Table of Contents

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