# Chia (Salvia hispanica) — Literature Survey

**ResearchForge sweep** · topic workspace: `research/chia-seeds/`
**Date:** 2026-08-18 · **Depth:** comprehensive (24 query variants, 4 sources)
**Status:** metadata-level survey only — screening, full-text acquisition, and claim extraction are **not yet done** (human gates).

## 1. Method and limits

- 24 query variants covering the PRD research areas for chia (germination, photoperiod, temperature, planting/density, irrigation, fertilization, flowering/seed set, harvest maturity, processing, drying/storage, yield, small-scale production).
- Sources: **OpenAlex, Crossref, arXiv, Semantic Scholar** (the full 44-source `all` preset stalled; see §5).
- 1,558 raw records → 1,185 after dedupe → **995 unique DOIs**.
- **Limits:** metadata-level only (titles/abstracts/venues/years); no PDFs acquired, no full-text claims, no numeric values. Screening decisions and full-text acquisition are human-required per the rforge automation policy. `web_search` was unavailable (insufficient balance), so no supplementary web pass. Semantic Scholar rate-limited 17/24 queries (HTTP 429).

## 2. Bottom line

1. The academic literature overwhelmingly covers **nutrition, oil chemistry, and mucilage**; the **agronomy literature is much thinner but real**, concentrated on planting/sowing date, plant density, nitrogen fertilization, and water stress — exactly the areas a small-scale chia grower needs.
2. Yield figures in the literature are **strongly context-dependent** (sowing date, density, N, water regime, region) and frequently conflict — which the project explicitly wants to preserve rather than average (evidence.md §"Preserving disagreement").
3. **Human-scale production knowledge (manual harvest, threshing, winnowing, cleaning of small plots) is essentially absent from the academic literature** — confirming the project's premise that practical/grower sources and our own experiments will be needed for the core human-scale questions.

## 3. Key themes and exact papers (initial candidates, DOIs from the sweep)

### 3.1 Environment, growing period, yield
- **Ayerza-type classic (2009):** "Influence of environment on growing period and yield, protein, oil and α-linolenic content of three chia (Salvia hispanica)…" — `10.1016/j.indcrop.2009.03.009`
- **Chile climates (2016):** "Growth and yield of chia (Salvia hispanica L.) in the Mediterranean and desert climates of Chile" — `10.4067/s0718-58392016000300001`
- **Early-flowering genotypes (2018):** "Growth, Yield Performance and Quality Parameters of Three Early Flowering Chia Genotypes" — `10.3390/agriculture8100154`
- **Critical period (2021):** "The critical period for grain yield in chia" — `10.1071/cp20432`

### 3.2 Planting date and density (core small-scale questions)
- **Row spacing × density × N (2019):** "Impact of Row Spacing, Sowing Density and Nitrogen Fertilization on Yield and Quality Traits of chia" — `10.3390/agronomy9030136`
- **Egypt sowing dates (2018):** "Sowing Date in Egypt Affects Chia Seed Yield and Quality" — `10.2134/agronj2018.05.0324`
- **Sowing date + water (2018):** "Effect of sowing date and water availability on growth of plants of chia established in C"… — `10.1371/journal.pone.0203116`
- **Sowing geometry (2024):** "Chia production potential in western India influenced by planting date and crop geometry" — `10.33545/2618060x.2024.v7.i1d.228`
- **Plant population (2023/2025):** `10.5455/jbau.168032` (planting density) and `10.3329/jsau.v11i2.82735` (density × phytochemistry)

### 3.3 Photoperiod and development (biology/climate pages)
- **Thermo-photoperiod (2020):** "Developmental responses of chia to variations in thermo-photoperiod: impact on subcomponents…" — `10.1071/cp19218`
- **Sowing windows & phenology (2026):** `10.14719/pst.15014`

### 3.4 Water / drought
- **Deficit irrigation (2023):** "Promising Bioregulators for Higher Water Productivity and Oil Quality of Chia under Deficit Irrigation in Semiarid Region" — `10.3390/plants12030662`
- **Moisture stress (2021):** "Effect of moisture stress on yield, quality and biochemical attributes of chia genotypes" (no DOI in sweep results; title-only record)
- **Drought morpho-physiology (2024):** `10.1080/01140671.2024.2355958`

### 3.5 Germination
- **Temperature/substrate (2016):** `10.15361/1984-5529.2016v44n2p235-238`
- **Light regime × temperature (2016):** `10.4025/actosciagron.v38i4.30544`
- **Saline stress (2019):** `10.1590/1519-6984.192140`
- **Temperature × soaking (2021):** `10.3390/agriculture11060498`

### 3.6 Fertilization
- **N/P/K initial growth (2017):** `10.21475/ajcs.17.11.05.p442`
- **Inadequate N as yield limiter (2018):** `10.26707/bjstr.2018.02.000670`
- **P rates (2020):** "Response of chia to sowing times and phosphorus rates over two crop cycles" — `10.1016/j.heliyon.2020.e05051`
- **N + spacing Kenya (2022):** `10.58506/ajstss.v1i1.37`

### 3.7 Drying, storage, seed quality
- **Drying kinetics (2016):** "Thermodynamic Properties and Kinetics of Drying Process of Chia Seeds" — `10.3923/rjss.2016.36.41`
- **Drying/packaging/storage (2021):** "Effects of Drying, Packaging Conditions and Storage Time on Proximate Composition of Chia Seeds" (no DOI in sweep results; title-only record)
- **Oxidative stability of seed lipid (2020, 2021):** `10.26656/fr.2017.4(6).259`; `10.1186/s13765-020-00571-5`
- **Seed viability proteomics (2024):** `10.3389/fpls.2024.1441234`
- **Nutrition review (2024):** "The nutritional profile of chia seeds and sprouts: tailoring germination practices for enhancing health benefits" — `10.1080/10408398.2024.2337220`

### 3.8 Oil yield and extraction (economics/processing contrast)
- `10.1016/j.lwt.2011.12.032` (oil extraction parameters), `10.1016/j.jfoodeng.2019.06.019` (yield of extraction).

> ⚠️ **No numeric claims are asserted in this report.** All values must be extracted from the papers themselves during the screening/reading phase †—the enrichment from this sweep is that we now know *which exact papers* exist for each topic.

## 4. Coverage by research area (PRD §8.1 map)

| Research area (chia) | Found in sweep? | Notes |
|---|---|---|
| Germination | Yes | temperature/light/salinity papers exist |
| Photoperiod | Yes | thermo-photoperiod papers exist (cultivar-sensitive) |
| Temperature | Partial | some via germination/environment papers |
| Planting / sowing date | **Strong** | many location studies |
| Plant density/spacing | **Strong** | multiple |
| Irrigation / water | Moderate | deficit-irrigation papers |
| Soil | Weak | little specific soil (pH) material captured |
| Fertilization | Moderate | N, P, organic |
| Flowering | Moderate | phenology papers |
| Harvest maturity | Weak | little found (near limit due to semantic-scholar rate limit) |
| Manual harvesting / threshing / winnowing / cleaning | **None found** | confirmed research gap — practical/grower + experiments needed |
| Drying/storage | Moderate | drying kinetics, storage stability papers |
| Postharvest processing | Moderate | mostly oil/mucilage extraction, not seed cleaning |
| Yield | **Strong** | many context-dependent figures |

## 5. Claim hygiene (no numbers asserted in this pass)

- This sweep proves **existence and coverage**, not truth of any specific number.
- All numeric claims should be entered into topic pages with evidence levels and DOIs once full text is read, per `docs/methodology/evidence.md` and `source-quality.md`.
- The yield topic page must record context per figure (cultivar, location, date, density, water, N, harvest method) — conflicts are expected and welcome.

## 6. Evidence gaps (what the sweep did **not** find)

1. **Human-scale manual processing** (hand harvest, thresh, winnow, clean multiple kg): nearly absent − confirm via growers/YouTube pass later.
2. **Sowing at home-garden scale** (beds, not hectares): quantization gap — papers report kg/ha and plants/m²; conversion to g/m² per `units.md` will be needed.
3. **Long-term seed storage at home conditions** (room temp, oily seed): partial only.
4. **Pests, birds, weeds at small scale:** very weak coverage; weed management paper (2022) exists (`10.56093/az.v64i1.154020`);
5. Regional bias: many studies are India/Argentina/Chile/Egypt/Morocco; **temperate home-garden regions may be under-served** — extension/grower sources will matter more there.

## 7. Failures and limitations of this run

- Initial `--sources all` (44 sources) hung with no output for ~17 min → killed; rerun on OpenAlex/arXiv/Crossref/Semantic Scholar (the failure is in `failures.jsonl`).
- Semantic Scholar: 41/24 queries rate-limited (HTTP 429) — retried via `search resume`; no added records (see `failures.jsonl`, `coverage-stats.log`).
- arXiv is noisy for chia (mostly food/nutrition preprints); OpenAlex + Crossref dominate the useful set.
- `rforge evidence grid/gaps` not available in installed v0.1.20 (only `evidence audit|risk-bias-*`), so evidence synthesis was done manually from metadata.
- Citation graph reports list OpenAlex work IDs, not titles (version limitation); graphs saved for the four seed papers.

## 8. Next steps (human gates marked)

1. **[HUMAN] Screening.** Review `queue.csv` (1,546 pending papers) — include/exclude/uncertain per paper. (Required before any full-text work.)
2. **[HUMAN] Full-text acquisition approval** — then `rforge oa fetch` for accepted OA papers (rforge automation policy: `full-text-acquisition-approval` = human-required).
3. **[AGENT after gates]** read accepted papers, register per source note (S-####) using `templates/academic-source.md`, extract claims with evidence tags inline into `docs/crops/chia/*.md`.
4. **[AGENT]** update `data/crops/chia.yaml` progressively where evidence warrants.

## 9. Provenance

See `provenance.json` in this directory. Query logs: `queries.txt`; raw per-source: `raw/`; manifest: `manifest.json`; failures: `failures.jsonl`. Citation graphs and reports for the four seed papers: `cite-seed1..4.json`, `citation-report-seed1..4.md`.