[
  {
    "effect_size": 16.0,
    "effect_unit": "%",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "Greenhouse sweet pepper 'Ferrari', 7.16 stems/m², peat, 16-week red-fruit harvest. Intra-canopy PPFD at fruit level was only 5–10% of top-of-canopy without LEDs. Marketable yield 14.6 vs 12.6 kg/m². Gain mainly from fruit number. Fruit colour deeper red (faster maturity). Electricity cost covered by extra yield at then-current prices; overall profit sensitive to yield gain, fruit price, and install cost.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://doi.org/10.17660/ActaHortic.2012.956.4",
    "potential_yield_effect": 16.0,
    "geography": "Northern greenhouse (Finland); high-latitude winter light analogous to Prairie winter",
    "intervention": "Intra-canopy LED, 57 W/m², no top lighting",
    "comparator": "No artificial light",
    "dose": "",
    "dose_unit": "",
    "limitations": "Single cultivar and season. LED efficacy has improved since 2012, which would raise, not lower, the economic case if yield holds.",
    "source_year": 2012,
    "doi": "10.17660/ActaHortic.2012.956.4",
    "baseline": "",
    "factor_id": "pepper-led-interlighting",
    "crop_id": "pepper",
    "factor": "LED interlighting between two-stem plants",
    "factor_category": "Light",
    "direction": "positive",
    "effect_type": "yield_gain",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "Moderate",
    "prairie_relevance": "high",
    "source_title": "Improving sweet pepper productivity by LED interlighting (Jokinen, Särkkä & Näkkilä 2012)",
    "notes": "One of the few pepper lighting papers that also reports a cost-benefit statement. Alberta winter DLI is similarly limiting."
  },
  {
    "effect_size": null,
    "effect_unit": "",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "24-week greenhouse trial, cultivars 'Gialte' and 'Margrethe'. 190 µmol m⁻² s⁻¹ white plus 0, 50, or 100 µmol m⁻² s⁻¹ FR. Fruit dry yield increased linearly with cumulative FR. Mechanism: higher plant source strength (dry weight), slight rise in fruit dry-matter fraction, higher fruit set (more fluctuating). Fruit cracking (medium/severe) fell from 17% ('Gialte') and 25% ('Margrethe') without FR to 8% with additional FR.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://doi.org/10.1016/j.scienta.2024.113787",
    "potential_yield_effect": null,
    "geography": "Greenhouse sweet pepper",
    "intervention": "Far-red added to white supplementary light",
    "comparator": "White supplementary light without extra FR",
    "dose": "",
    "dose_unit": "",
    "limitations": "No single percent yield is quoted in the abstract for the full-season 100 µmol FR treatment. Do not invent one.",
    "source_year": 2024,
    "doi": "10.1016/j.scienta.2024.113787",
    "baseline": "",
    "factor_id": "pepper-far-red-supplement",
    "crop_id": "pepper",
    "factor": "Additional far-red in supplementary lighting",
    "factor_category": "Light",
    "direction": "positive",
    "effect_type": "yield_gain",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "Moderate",
    "prairie_relevance": "moderate",
    "source_title": "Additional far-red increases fruit yield of greenhouse sweet pepper mainly through enhancing plant source strength (2024)",
    "notes": "Quality (less cracking) and yield moved together. Linear FR response means dose matters; a short 4-week FR pulse was also tested."
  },
  {
    "effect_size": 15.0,
    "effect_unit": "% fruit weight (upper end)",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "Six-month Ontario winter greenhouse, cultivars 'Eurix' and 'Gina', 175 µmol m⁻² s⁻¹. Green fractions 0, 12, 24, 43% versus red/blue. Fruit weight +2 to +15% depending on cultivar and green fraction. Fruit dry-matter content rose linearly with green %. Light 3 m down the canopy was 43–158% higher with green.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://doi.org/10.1016/j.scienta.2022.111350",
    "potential_yield_effect": 15.0,
    "geography": "Harrow / Ontario greenhouse winter production (AAFC)",
    "intervention": "White/green-containing LED vs red/blue",
    "comparator": "Red/blue LED at the same PPFD",
    "dose": "",
    "dose_unit": "",
    "limitations": "Range +2–15%; the +15% is the upper cultivar × spectrum combination, not a mean.",
    "source_year": 2022,
    "doi": "10.1016/j.scienta.2022.111350",
    "baseline": "",
    "factor_id": "pepper-green-light-ontario",
    "crop_id": "pepper",
    "factor": "Green photons in LED spectrum (canopy penetration)",
    "factor_category": "Light",
    "direction": "positive",
    "effect_type": "yield_gain",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "Moderate",
    "prairie_relevance": "high",
    "source_title": "Addition of green light improves fruit weight and dry matter content in sweet pepper due to greater light penetration within the canopy (Lanoue, Little, Hawley & Hao 2022)",
    "notes": "Prairie-relevant: AAFC greenhouse vegetable lighting programme. Effect is fruit weight and dry matter, not always total kg/m². Kusuma et al. 2021 (Plants 10:637) found green increased tomato dry mass but not lettuce or cucumber — crop-specific."
  },
  {
    "effect_size": null,
    "effect_unit": "",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "AAFC Harrow, 3 winters, tomato and sweet pepper. 16–17 h vs 20–21 h overhead HPS; intra-canopy LED photoperiods 0–24 h. Dynamic temperature integration dropped to 15.5°C (pepper) or 13.5°C (tomato) at end of photoperiod, same 24-h mean. Temperature drop reduced photo-injury (chlorosis, necrotic spotting) and increased fruit yield at long photoperiods, and cut heating energy in cold months.",
    "study_count": 3,
    "comparison_count": null,
    "source_url": "https://doi.org/10.17660/ActaHortic.2017.1182.22",
    "potential_yield_effect": null,
    "geography": "Harrow, Ontario — AAFC greenhouse compartments",
    "intervention": "20–21 h lighting + dynamic TI with temperature drop",
    "comparator": "16–17 h lighting, no temperature drop",
    "dose": "",
    "dose_unit": "",
    "limitations": "Abstract does not report a numeric % yield. Photo-injury is the constraint that the temperature drop relieves.",
    "source_year": 2017,
    "doi": "10.17660/ActaHortic.2017.1182.22",
    "baseline": "",
    "factor_id": "pepper-long-photoperiod-temp-drop",
    "crop_id": "pepper",
    "factor": "Long photoperiod of supplemental light with end-of-day temperature drop",
    "factor_category": "Climate",
    "direction": "positive",
    "effect_type": "yield_gain",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "High",
    "prairie_relevance": "high",
    "source_title": "Temperature drop improved responses of greenhouse fruit vegetables to long photoperiod of supplemental lighting (Hao, Zhang, Guo, Little, Zheng & Khosla 2017)",
    "notes": "Directly addresses the Prairie winter problem: more hours of light without leaf injury. Yield increased; a single pooled percent is not given in the abstract."
  },
  {
    "effect_size": null,
    "effect_unit": "",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "2023 Alberta greenhouse survey. Peppers had among the lower total production costs per m² ($93.42/m² reported as the low among crops) and positive gross margin / return to unpaid labour. Area is smaller than cucumber or tomato in Alberta.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://open.alberta.ca/dataset/fbb2b0b5-53b9-4dbd-92b7-f37ec8ed9369/resource/f4313ce0-1ea0-45e0-bc34-18306b1d2128/download/agi-economics-production-marketing-greenhouse-crops-2023.pdf",
    "potential_yield_effect": null,
    "geography": "Alberta",
    "intervention": "Observed pepper enterprise",
    "comparator": "Other Alberta greenhouse crops",
    "dose": "",
    "dose_unit": "",
    "limitations": "Survey, not a lighting trial.",
    "source_year": 2025,
    "doi": "",
    "baseline": "",
    "factor_id": "pepper-agriprofits-returns",
    "crop_id": "pepper",
    "factor": "Alberta AgriProfit$ 2023 pepper cost and returns",
    "factor_category": "Economics & Certification",
    "direction": "positive",
    "effect_type": "other",
    "evidence_type": "economic_benchmark",
    "evidence_strength": "High",
    "prairie_relevance": "high",
    "source_title": "Economics of Production and Marketing of Greenhouse Crops in Alberta 2023 (Laate)",
    "notes": "Pepper lighting and FR investments should be scored against this COP. Coloured fruit and Class I packout drive price more than raw kg/m²."
  },
  {
    "effect_size": null,
    "effect_unit": "",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "Alberta Agriculture greenhouse pepper guide. Fruit set declines above 27°C and under low RH. At 32–38°C style elongation reduces set (Khah & Passam 1992). Optimum 24-h temperature for yield ~21°C; flowering/set optimum ~16°C night/target. Root-zone ~15°C keeps plants vegetative and increases flower/young-fruit abortion versus 20°C. Pad-and-fan or mist usually required to hold targets in Alberta summers.",
    "study_count": null,
    "comparison_count": null,
    "source_url": "https://www.alberta.ca/production-of-sweet-bell-peppers",
    "potential_yield_effect": null,
    "geography": "Alberta commercial greenhouse pepper",
    "intervention": "Supra-optimal air temperature or cold root-zone",
    "comparator": "~21°C 24-h mean; ~20°C root-zone",
    "dose": "",
    "dose_unit": "",
    "limitations": "Extension synthesis (evidence tier E/review), not a new factorial trial. Magnitude is cultivar- and season-specific.",
    "source_year": 2026,
    "doi": "",
    "baseline": "",
    "applicability": "direct",
    "evidence_tier": "E",
    "factor_id": "pepper-heat-fruit-set-alberta",
    "crop_id": "pepper",
    "factor": "Air temperature above 27°C reducing fruit set; root-zone below 20°C increasing abortion",
    "factor_category": "Stress",
    "direction": "negative",
    "effect_type": "yield_loss",
    "evidence_type": "review",
    "evidence_strength": "High",
    "prairie_relevance": "high",
    "source_title": "Production of sweet bell peppers (Government of Alberta)",
    "notes": "Direct Alberta production guidance synthesizing experimental literature. Heat is a summer constraint; cold slabs are a winter constraint. No single pooled % is given — do not invent one."
  },
  {
    "effect_size": -35.0,
    "effect_unit": "% fruit mass (PHR18 at 75 days)",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "Two plastic greenhouses, Korea 2022–2023. Daytime 28°C vs 30°C. Accession PHR18: −45% total mass and −34% fruit at 35 days; −35% total and −32% fruit at 75 days. PHR23 initially gained fruit (+64% at 35 days) then lost −35% fruit by 75 days. Cultivar × duration interaction.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://doi.org/10.3389/fpls.2025.1590193",
    "potential_yield_effect": -35.0,
    "geography": "Wanju, Korea plastic greenhouses",
    "intervention": "Daytime 30°C vs 28°C",
    "comparator": "28°C daytime greenhouse",
    "dose": "",
    "dose_unit": "",
    "limitations": "Not Alberta. Accessions are breeding lines. Only two setpoints.",
    "source_year": 2025,
    "doi": "10.3389/fpls.2025.1590193",
    "baseline": "",
    "applicability": "near-direct",
    "evidence_tier": "B",
    "factor_id": "pepper-heat-greenhouse-trial-2025",
    "crop_id": "pepper",
    "factor": "Sustained greenhouse heat (+2°C daytime setpoint)",
    "factor_category": "Stress",
    "direction": "negative",
    "effect_type": "yield_loss",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "Moderate",
    "prairie_relevance": "moderate",
    "source_title": "Simulation of the impacts of high temperature stress on pepper (Capsicum annuum L.) yields (2025)",
    "notes": "Shows heat penalty is cultivar- and duration-specific. A +2°C air-temperature step is within Alberta summer greenhouse spikes. Do not treat −35% as a universal pepper heat coefficient."
  },
  {
    "effect_size": null,
    "effect_unit": "",
    "ci_lower": null,
    "ci_upper": null,
    "conditions": "High-latitude winter sweet pepper under high-intensity artificial lighting with optimized plant density. PeerJ 2026 reports enhanced yield from combining lighting intensity and density. Use as a density × light interaction, not a standalone density percentage.",
    "study_count": 1,
    "comparison_count": null,
    "source_url": "https://doi.org/10.7717/peerj.21491",
    "potential_yield_effect": null,
    "geography": "High-latitude winter greenhouse",
    "intervention": "High-intensity lighting plus density optimization",
    "comparator": "Lower light and/or non-optimized density",
    "dose": "",
    "dose_unit": "",
    "limitations": "Numeric yield effect not copied from tables here (numeric_extraction_required if a single % is needed).",
    "source_year": 2026,
    "doi": "10.7717/peerj.21491",
    "baseline": "",
    "applicability": "near-direct",
    "evidence_tier": "B",
    "factor_id": "pepper-winter-lighting-density",
    "crop_id": "pepper",
    "factor": "High-intensity winter lighting with optimized plant density (high latitude)",
    "factor_category": "Light",
    "direction": "positive",
    "effect_type": "yield_gain",
    "evidence_type": "greenhouse_trial",
    "evidence_strength": "Moderate",
    "prairie_relevance": "high",
    "source_title": "Enhanced sweet pepper yield through high-intensity artificial lighting and optimized plant density in high-latitude winter production (2026)",
    "notes": "Prairie-relevant winter production context. Abstract emphasizes the interaction; extract a numeric % from the paper before using it in an economic model."
  }
]