[ { "effect_size": 40.0, "effect_unit": "%", "ci_lower": null, "ci_upper": null, "conditions": "Greenhouse truss tomato. Treatment = solar + supplemental LED, or solar + HPS + LED, versus solar-only or solar + HPS. Effects vary with spectrum, photoperiod, and background DLI; some individual trials were null or negative.", "study_count": 31, "comparison_count": 100, "source_url": "https://doi.org/10.3389/fpls.2021.596927", "potential_yield_effect": 40.0, "geography": "Global greenhouse trials (31 papers)", "intervention": "Supplemental LED lighting", "comparator": "Solar only, or solar + HPS without LED", "dose": "", "dose_unit": "", "limitations": "Pooled +40% mixes winter high-latitude lighting with milder climates. Profit depends on electricity price, lamp efficiency, and fruit price. Some trials reported no yield gain.", "source_year": 2021, "doi": "10.3389/fpls.2021.596927", "baseline": "", "factor_id": "tomato-led-supplemental-meta", "crop_id": "tomato", "factor": "Supplemental LED lighting (top and/or intra-canopy)", "factor_category": "Light", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "meta_analysis", "evidence_strength": "High", "prairie_relevance": "high", "source_title": "Supplemental LED Lighting Effectively Enhances the Yield and Quality of Greenhouse Truss Tomato Production: Results of a Meta-Analysis (Appolloni et al. 2021)", "notes": "Mean yield +40% (p<0.001); also TSS +6%, ascorbic acid +11%, chlorophyll +31%, net photosynthesis +50%, leaf area +9%. Stomatal conductance not significant. Yield Hedges' g = 1.75 (k=68). Electricity cost is not subtracted from the yield effect." }, { "effect_size": 32.9, "effect_unit": "%", "ci_lower": null, "ci_upper": null, "conditions": "Meta-analysis of 114 articles on vegetable yield under elevated CO2. Fresh-yield mean +32.9% (n=7324 observations); dry-yield +38.2% (n=1583). Tomato-specific greenhouse responses in the broader literature range from about +7% to more than +100% depending on concentration (often 450–1200 ppm) and light.", "study_count": 114, "comparison_count": 7324, "source_url": "https://doi.org/10.17660/ActaHortic.2020.1296.36", "potential_yield_effect": 32.9, "geography": "Global protected and experimental vegetable crops", "intervention": "Elevated atmospheric / greenhouse CO2", "comparator": "Ambient CO2", "dose": "", "dose_unit": "", "limitations": "Pooled vegetable mean, not tomato-only. Quality (especially some micronutrients) can decline under eCO2. Enrichment is ineffective when vents are open.", "source_year": 2020, "doi": "10.17660/ActaHortic.2020.1296.36", "baseline": "", "factor_id": "tomato-co2-vegetable-meta", "crop_id": "tomato", "factor": "Elevated CO2 (vegetable meta-analysis, includes tomato)", "factor_category": "CO2 / carbon availability", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "meta_analysis", "evidence_strength": "High", "prairie_relevance": "high", "source_title": "The impact of elevated CO2 on yield of vegetables (Dong, Gruda, Li & Duan 2020)", "notes": "Yield gain attributed mainly to more organs (+32.0%) and a higher harvest index (+23.1%). Closed-vent Alberta winter houses can hold 800–1000 ppm; venting in summer limits enrichment." }, { "effect_size": 60.8, "effect_unit": "% yield/plant", "ci_lower": null, "ci_upper": null, "conditions": "Autumn–spring greenhouse tomato. CO2 enrichment alone +19.0% yield/plant; supplemental light alone +35.6%; combined +60.8%. Single-fruit weight +16.2%, +28.9%, and +36.6% respectively.", "study_count": 1, "comparison_count": null, "source_url": "https://journals.ashs.org/hortsci/view/journals/hortsci/54/2/article-p246.xml", "potential_yield_effect": 60.8, "geography": "Greenhouse, autumn–spring cycle", "intervention": "Supplemental lighting plus CO2 enrichment", "comparator": "Ambient CO2 and no supplemental light", "dose": "", "dose_unit": "", "limitations": "Single-location trial. Combined 60.8% is not additive of the two main effects and should not be stacked with the LED meta-analysis +40%.", "source_year": 2019, "doi": "", "baseline": "", "factor_id": "tomato-light-co2-interaction", "crop_id": "tomato", "factor": "Combined supplemental light and CO2 enrichment", "factor_category": "Light", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "greenhouse_trial", "evidence_strength": "Moderate", "prairie_relevance": "high", "source_title": "Interaction of Supplementary Light and CO2 Enrichment Improves Growth, Photosynthesis, Yield, and Quality of Tomato in Autumn through Spring Greenhouse Production (Pan et al. 2019)", "notes": "Light was more effective than CO2 alone; the combination was synergistic. Directly relevant to Alberta winter DLI and closed-house CO2." }, { "effect_size": 37.0, "effect_unit": "% (mean of all heterografts)", "ci_lower": null, "ci_upper": null, "conditions": "159 publications, 202 rootstocks, 1023 treatments, open-field and greenhouse. Mean +37% across all heterograft data, but grafted plants were significantly higher-yielding in only 35% of cases; no difference in 58%; lower in 6%. Self-grafts ≈ non-grafted.", "study_count": 159, "comparison_count": 1023, "source_url": "https://doi.org/10.1007/s13593-018-0507-5", "potential_yield_effect": 37.0, "geography": "Global; open-field and greenhouse", "intervention": "Scion grafted onto a different tomato rootstock", "comparator": "Non-grafted or self-grafted plants", "dose": "", "dose_unit": "", "limitations": "The +37% mean is pulled up by stress/disease trials. Do not apply it as a default Alberta hydroponic premium.", "source_year": 2018, "doi": "10.1007/s13593-018-0507-5", "baseline": "", "factor_id": "tomato-grafting-meta", "crop_id": "tomato", "factor": "Heterografting onto tomato rootstocks", "factor_category": "Genetics", "direction": "context_dependent", "effect_type": "yield_gain", "evidence_type": "meta_analysis", "evidence_strength": "High", "prairie_relevance": "moderate", "source_title": "Yield and fruit quality of grafted tomatoes, and their potential for soil fumigant use reduction. A meta-analysis (Grieneisen et al. 2018)", "notes": "Largest benefits when soilborne disease, nematodes, or abiotic stress are present. In soilless high-wire systems without those stresses, grafting is often a cost with little yield gain." }, { "effect_size": 53.1, "effect_unit": "percentage points fruit set", "ci_lower": null, "ci_upper": null, "conditions": "Commercial Leamington, Ontario tomato greenhouses. Fruit set 30.2% with no bee visits versus 83.3–100% at bruising levels 1–4. Weight and diameter rose from zero visits to one visit; no further weight gain above bruising level 1, no further seed gain above level 2. Colony density 7–15 hives/ha typically sufficient.", "study_count": 1, "comparison_count": null, "source_url": "https://doi.org/10.1603/0022-0493-94.1.172", "potential_yield_effect": 53.1, "geography": "Leamington, Ontario commercial tomato greenhouses", "intervention": "Bombus impatiens visits (anther-cone bruising as intensity proxy)", "comparator": "Unvisited flowers", "dose": "", "dose_unit": "", "limitations": "Parthenocarpic cultivars and hormone set change the comparator. Over-visitation (bruising ≥3) can damage flowers.", "source_year": 2001, "doi": "10.1603/0022-0493-94.1.172", "baseline": "", "factor_id": "tomato-bumblebee-pollination", "crop_id": "tomato", "factor": "Bumble bee buzz-pollination versus no visit or hormone set", "factor_category": "Crop management", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "greenhouse_trial", "evidence_strength": "High", "prairie_relevance": "high", "source_title": "Effect of bumble bee pollination intensity on the quality of greenhouse tomatoes (Morandin, Laverty & Kevan 2001)", "notes": "Fruit-set gain is +53.1 percentage points (30.2% → 83.3% at bruising level 1), not a 53% fruit-weight increase. Companion paper (JEE 94:462–467) found 7–15 colonies/ha and ~2000 trips/ha/day adequate. UV-transmitting covers increased bee activity 94% (Can. Entomol. 133:883–893). Alberta houses using Bombus should follow the same density and over-visitation guidance." }, { "effect_size": 1.914, "effect_unit": "SMD fruit number", "ci_lower": 1.432, "ci_upper": 2.395, "conditions": "Meta-analysis of 15 tomato studies (from 398 screened). Random-effects SMDs: fruit number 1.914 (95% CI 1.432–2.395); fruit weight 2.08 (1.42–2.73); fruit diameter 1.39 (0.29–2.48). Heterogeneity I² up to 80.6%. Moderators: strain, dose, application method, DAP, temperature.", "study_count": 15, "comparison_count": null, "source_url": "https://pubmed.ncbi.nlm.nih.gov/41028103/", "potential_yield_effect": null, "geography": "Mixed; not Alberta-specific", "intervention": "Bacillus spp. inoculation or application", "comparator": "Uninoculated tomato", "dose": "", "dose_unit": "", "limitations": "High heterogeneity. Many trials are soil/pot, not commercial soilless tomato. Do not treat SMD ≈ percent yield.", "source_year": 2025, "doi": "", "baseline": "", "factor_id": "tomato-bacillus-biofertilizer-meta", "crop_id": "tomato", "factor": "Bacillus spp. biofertilizer / PGPR", "factor_category": "Biological inputs", "direction": "positive", "effect_type": "other", "evidence_type": "meta_analysis", "evidence_strength": "Moderate", "prairie_relevance": "low", "source_title": "Meta-analysis of biofertilizer effects of Bacillus species on tomato yield (2025)", "notes": "SMDs are standardized mean differences, not percent yield. Convert to percent only within a given trial. Strongest as a biological input under disease or nutrient-limited soil; weaker evidence in clean hydroponic slabs." }, { "effect_size": -0.66, "effect_unit": "$/m² return to equity", "ci_lower": null, "ci_upper": null, "conditions": "Blended Alberta greenhouse survey for the 2023 crop. Tomato was the only major greenhouse crop with negative return to equity (−$0.66/m²). Gross margins were still positive. Provincial greenhouse industry gross revenue ~$278.3 million; assets ~$440.8 million.", "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 2023 tomato enterprise (surveyed growers)", "comparator": "Other Alberta greenhouse enterprises in the same survey", "dose": "", "dose_unit": "", "limitations": "Survey year 2023; not a randomized intervention. Confidentiality limits sample size. Do not treat −$0.66/m² as a biological yield effect.", "source_year": 2025, "doi": "", "baseline": "", "factor_id": "tomato-agriprofits-return-equity", "crop_id": "tomato", "factor": "Alberta AgriProfit$ 2023 tomato return to equity", "factor_category": "Economics & Certification", "direction": "negative", "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, Alberta Agriculture and Irrigation)", "notes": "A yield-boosting factor only raises profit if it covers energy, labour, and marketing. In 2023 Alberta tomatoes, cost structure (labour, gas, packaging) offset receipts. Lettuce had the highest gross return per m² in the same report." }, { "effect_size": 11.0, "effect_unit": "% (upper of 8–11% range)", "ci_lower": null, "ci_upper": null, "conditions": "Wageningen commercial-management tomato crop, Dec 2010–Nov 2011. Diffuse glass haze 45/62/71% with transmission ≥ standard glass vs clear glass. Production +7–9% by June and +8–11% by year-end. Mainly heavier fruit (+5–8 g). Slightly more generative; less late-season Botrytis. Commercial grower pairs later showed ~8% higher radiation-use efficiency under diffuse roofs.", "study_count": 1, "comparison_count": null, "source_url": "https://research.wur.nl/en/publications/influence-of-diffuse-glass-on-the-growth-and-production-of-tomato", "potential_yield_effect": 11.0, "geography": "Bleiswijk, Netherlands (high-latitude glasshouse)", "intervention": "Diffuse glass covering (45–71% haze)", "comparator": "Standard clear glass", "dose": "", "dose_unit": "", "limitations": "Single-year WUR trial plus later commercial RUE analysis. Upper +11% is the 71% haze treatment, not a mean of all haze levels.", "source_year": 2012, "doi": "", "baseline": "", "applicability": "near-direct", "evidence_tier": "B", "factor_id": "tomato-diffuse-glass", "crop_id": "tomato", "factor": "Diffuse greenhouse glass (haze 45–71%)", "factor_category": "Climate", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "greenhouse_trial", "evidence_strength": "High", "prairie_relevance": "high", "source_title": "Influence of diffuse glass on the growth and production of tomato (Dueck, Janse, Li, Kempkes & Eveleens 2012)", "notes": "High-latitude winter-to-autumn tomato. Mechanism is deeper, more even canopy light, not more total light. Do not stack with the LED +40% meta-analysis. Commercial follow-up (WUR 2021) found ~8% higher RUE and no extra energy use." }, { "effect_size": -5.5, "effect_unit": "% (tomato at >80% of full irrigation)", "ci_lower": null, "ci_upper": null, "conditions": "Global vegetable deficit-irrigation meta-analysis. Yield penalty rises as irrigation falls below ~65% of full irrigation. Greenhouse DI cut yield less than open-field DI; greenhouse water-productivity gain 18.4% vs 13.6% in the field. Tomato: significant WP gain with as little as 5.5% yield reduction at low deficit (>80% FI).", "study_count": null, "comparison_count": null, "source_url": "https://doi.org/10.1038/s41598-021-01433-w", "potential_yield_effect": -5.5, "geography": "Global open-field and greenhouse vegetable trials", "intervention": "Irrigation below full crop evapotranspiration", "comparator": "Full irrigation (FI)", "dose": "", "dose_unit": "", "limitations": "Pooled vegetables; tomato-specific −5.5% is the mild-deficit (>80% FI) case. Severe deficit (<65% FI) has much larger penalties.", "source_year": 2021, "doi": "10.1038/s41598-021-01433-w", "baseline": "", "applicability": "near-direct", "evidence_tier": "A", "factor_id": "tomato-deficit-irrigation-veg-meta", "crop_id": "tomato", "factor": "Deficit irrigation (vegetable meta-analysis; greenhouse vs field)", "factor_category": "Water", "direction": "negative", "effect_type": "yield_loss", "evidence_type": "meta_analysis", "evidence_strength": "High", "prairie_relevance": "moderate", "source_title": "A global meta-analysis of yield and water productivity responses of vegetables to deficit irrigation (2021)", "notes": "Direction is yield loss vs full irrigation, with a water-productivity gain. In Alberta, water is often not the binding constraint compared with heat and light; use this as a WUE trade-off, not a yield booster." }, { "effect_size": 9.8, "effect_unit": "% (from excess water down to optimum)", "ci_lower": null, "ci_upper": null, "conditions": "Meta-analysis of 49 tomato studies, 733 observations, 10 countries. Moving supra-optimal water to optimal: yield +9.8%, WUE +19.6%, NUE +3.7%. Moving supra-optimal N to optimal: yield +5.6%, WUE +6.3%, NUE +50.5%. Water and N savings of 41% (240 mm) and 37% (138 kg N/ha) without yield loss when starting from excess.", "study_count": 49, "comparison_count": 733, "source_url": "https://doi.org/10.1016/j.agwat.2018.08.013", "potential_yield_effect": 9.8, "geography": "Global tomato trials (field and protected)", "intervention": "Reduce water or N from supra-optimal to optimal", "comparator": "Supra-optimal water or N input", "dose": "", "dose_unit": "", "limitations": "Mixes field and greenhouse. Optimum is context-specific. Not a fertilizer-increase study.", "source_year": 2018, "doi": "10.1016/j.agwat.2018.08.013", "baseline": "", "applicability": "near-direct", "evidence_tier": "A", "factor_id": "tomato-water-n-optimum-meta", "crop_id": "tomato", "factor": "Cutting supra-optimal water and nitrogen to the agronomic optimum", "factor_category": "Nutrients", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "meta_analysis", "evidence_strength": "High", "prairie_relevance": "moderate", "source_title": "Water- and nitrogen-saving potentials in tomato production: A meta-analysis (Du et al. 2018)", "notes": "This is a penalty-from-excess result, not a recommendation to starve the crop. Interaction of water × N must be considered; do not add the +9.8% and +5.6% as independent gains." }, { "effect_size": null, "effect_unit": "", "ci_lower": null, "ci_upper": null, "conditions": "High greenhouse VPD (often 3–5 kPa after sunrise in arid houses) limits fruit calcium, raises blossom-end rot and cracking, and cuts yield. Reducing VPD increased fruit and peel calcium, yield, and yield-WUE in two cultivars. Stage-specific VPD (higher at flowering, lower at fruit expansion) has been proposed to raise fruit Ca without continuous humidification.", "study_count": 1, "comparison_count": null, "source_url": "https://www.sciencedirect.com/science/article/abs/pii/S0098847222000089", "potential_yield_effect": null, "geography": "Arid/continental greenhouse tomato", "intervention": "VPD reduction (humidification / climate control)", "comparator": "High-VPD greenhouse air", "dose": "", "dose_unit": "", "limitations": "Abstract reports yield increase without a single pooled percent. Do not invent one. Humidification has energy and Botrytis costs.", "source_year": 2022, "doi": "", "baseline": "", "applicability": "direct", "evidence_tier": "B", "factor_id": "tomato-vpd-calcium-yield", "crop_id": "tomato", "factor": "Lowering high VPD to restore fruit calcium and marketable yield", "factor_category": "Climate", "direction": "positive", "effect_type": "yield_gain", "evidence_type": "greenhouse_trial", "evidence_strength": "Moderate", "prairie_relevance": "high", "source_title": "Reducing vapor pressure deficit improves calcium absorption by optimizing plant structure, stomatal morphology, and aquaporins in tomatoes (2022)", "notes": "Alberta summer houses routinely exceed 2 kPa VPD. BER is a calcium-transport failure, not usually a fertilizer-Ca shortage. Foliar Ca sprays often fail to cut BER." }, { "effect_size": 14.0, "effect_unit": "% of fruit with BER (upper of 11.6–14%)", "ci_lower": null, "ci_upper": null, "conditions": "Four rockwool tomato cultivars. Nutrient-solution Ca nitrate at −50%, standard (0.85 mmol/L), +50%, and +100% from week 4. BER-affected fruit 11.6–14% overall; cultivars 9.3–21.3%; treatment × cultivar 7.1–22.5%. Marketable yield 13.77–25.24 kg/m². Ca concentration alone did not eliminate BER; microclimate for Ca transport remained essential.", "study_count": 1, "comparison_count": null, "source_url": "https://doi.org/10.17660/ActaHortic.2012.927.47", "potential_yield_effect": 14.0, "geography": "Soilless greenhouse tomato", "intervention": "Altered Ca nitrate in the nutrient solution", "comparator": "Standard Ca nutrient solution", "dose": "", "dose_unit": "", "limitations": "Not a percent total-yield meta-analysis. Standard solution still had BER.", "source_year": 2012, "doi": "10.17660/ActaHortic.2012.927.47", "baseline": "", "applicability": "direct", "evidence_tier": "B", "factor_id": "tomato-ber-calcium-solution", "crop_id": "tomato", "factor": "Blossom-end rot incidence under varied nutrient-solution calcium", "factor_category": "Nutrients", "direction": "negative", "effect_type": "yield_loss", "evidence_type": "greenhouse_trial", "evidence_strength": "Moderate", "prairie_relevance": "high", "source_title": "Incidence of tomato blossom-end rot at different calcium levels (2012)", "notes": "Shows BER as a saleable-yield leak (up to ~one-fifth of fruit in a susceptible cultivar). Raising solution Ca is cultivar-specific and insufficient without VPD/irrigation control." } ]