Fasahat 2015 — Recent progress in understanding cadmium toxicity and tolerance in rice
A single-author narrative review (Emirates Journal of Food and Agriculture, Special Issue “Salinity and Heavy Metal Stress”) synthesising the rice–cadmium literature on uptake pathways, accumulation, morphological and physiological responses, identified quantitative trait loci for grain Cd, and agronomic countermeasures. The paper reports no original experiments; all numerical anchors are cited from the underlying primary literature. Relevance to the wiki is as a consolidated entry point to the rice-Cd plant-science evidence base — useful for orienting readers and as a lead-source to the primary studies (Ishikawa, Ueno, Arao, Cui, Tezuka, Kashiwagi, Liu, Yu and others) it summarises, not as a source of original occurrence data for rice as sold or consumed.
Key numbers
All figures below are cited by Fasahat from the named primary sources; this review reports no original measurements.
- Cadmium biological half-life in humans: 10–30 years (Ellis et al., 1985, p.94).
- Soil-solution Cd in non-polluted soils: 0.04–0.32 µM (Wagner, 1993, p.95).
- Soil-solution Cd 0.32 to ~1 µM is “polluted to moderate” (Sanitá di Toppi and Gabreilli, 1999, p.95).
- Cd concentration in agricultural soils “usually lower than 1 mg kg⁻¹” (Adriano, 2001, p.95).
- Suggested standard for Cd in polished rice: 0.2–0.4 mg kg⁻¹ (Ishikawa, 2005, p.95). Basis stated as “the weight of polished rice”; wet/dry not specified by Fasahat.
- Soil pH effect: highest grain Cd at soil pH ~6 (Das et al., 1997, p.96); reduced uptake with rising pH (Hinesly et al., 1984, p.96). Optimal-grain-Cd pH is reported per the cited soil-chemistry literature; Fasahat does not derive a new value.
- Grain-filling timing: Cd in paddy rice grain accumulates predominantly during grain filling (Simmons et al., 2003, 2008, p.96), which coincides with the pre-harvest 2-week drainage of paddy.
- Tissue partitioning: roots > leaves > grains/seeds (Wagner, 1993; He et al., 2008; Pereira et al., 2011, p.96). Root Cd may represent >80% of total plant Cd (Cui et al., 2004; Liu et al., 2007, p.96).
- Root-to-grain translocation: ~0.73% of total Cd taken up by six rice cultivars was translocated to the grain in one Chinese study; embryo Cd ~5× that of chaff or polished rice (Liu et al., 2007, p.96).
- Peroxidase activity in Oryza sativa exposed to Cd: 10–20-fold higher in roots and leaves than controls (Reddy and Prasad, 1992, p.98).
- Seed-germination effects: stimulation at 0.01–1.5 µM CdCl₂; sharp decrease at 2.0 µM CdCl₂ (Wu et al., 2006, p.98). Photosynthesis unaffected at 50, 100 and 250 µM Cd(NO₃)₂ for one cultivar (Rascio et al., 2008, p.98).
- Yield response: 6.2–8.9% grain-yield reduction in Cd-tolerant genotypes vs 38.3–47.1% in Cd-susceptible genotypes at 150 mg kg⁻¹ soil Cd (Huang et al., 2008, p.99). 80% decline in tiller number and rice yield reported by Quynh et al. (2002, p.99). Plant height decreased by 64.7% at 20–40 mg kg⁻¹ soil Cd (Quynh et al., 2002, p.98–99).
- Pot-trial multi-metal toxicity ranking on rice cv. 616: Cu > Zn > As > Pb > Cd, for individual-metal growth effects across 0–300 mg kg⁻¹ Pb, 0–30 mg kg⁻¹ As, 0–200 mg kg⁻¹ Zn, 0–100 mg kg⁻¹ Cu, 0–1.5 mg kg⁻¹ Cd (Zhou et al., 2003, p.99).
- QTL findings (Table 1, p.97): QTLs for grain or shoot Cd concentration mapped on rice chromosomes 3, 4, 6, 7, 8, and 11 across Koshihikari/Kasalath CSSLs, Kasalath/Nipponbare BILs, JX17/ZYQ8 DHs, and Cho-Ko-Koku/Akita 63 F₂ populations using RFLP and SSR markers (Ishikawa et al., 2005b; Kashiwagi et al., 2009; Xue et al., 2009; Tezuka et al., 2010).
- OsHMA3 (P₁B-type ATPase, tonoplast-localised in root cells, identified by Ueno et al., 2010): functional allele sequesters Cd in root vacuoles; loss-of-function allele in cv. Anjana Dhan drives high root-to-shoot Cd translocation (p.97).
- qCdT7 (Tezuka et al., 2010, p.97): single recessive gene on chromosome 7 increases Cd translocation in cv. Cho-Ko-Koku; underlies higher Cd accumulation rather than higher root uptake.
Methods (brief)
Narrative review; no original experiments. Fasahat summarises ~135 cited references covering soil chemistry, agronomy, plant physiology, biochemistry, and quantitative-genetics literature on cadmium and rice through approximately 2013. Source-by-source methods, sample sizes, instrumentation, and reporting bases are not consolidated by the review; readers must consult the cited primary sources for those details. No PRISMA-style systematic-review methodology is declared; no inclusion/exclusion criteria, no search strategy, no bias assessment, and no meta-analytic synthesis of effect sizes — i.e., this is a narrative review, not a systematic review or meta-analysis.
Implications
Certification: Provides no original occurrence numbers, but consolidates the cited evidence base on grain Cd targets (e.g., the 0.2–0.4 mg kg⁻¹ polished-rice figure attributed to Ishikawa 2005), the role of grain-fill-stage hydrology in setting paddy-grain Cd, and the existence of cultivar-level variation traceable to OsHMA3 and chromosome-7 QTLs that influence grain-Cd outcomes. The wiki’s rice-Cd synthesis should rely on the cited primary studies (Ishikawa, Ueno, Arao, Cui, Tezuka, Kashiwagi, Liu, Yu, Pereira, Wu) rather than on Fasahat’s secondhand restatements when those primary papers are available.
Courses: Useful as a single orienting reading for the rice-Cd plant-science storyline — uptake → root-to-shoot translocation via xylem → grain loading via phloem (per Tanaka et al., 2007) → cultivar variation traceable to OsHMA3 and qCdT7 → agronomic levers (soil amendments, water management, soil dressing, low-Cd breeding, phytoextraction). Pair with the primary mechanism papers (e.g., Mostofa 2015 on H₂S signalling, Ueno 2010 on OsHMA3) for mechanism depth.
App: No occurrence or consumption-anchored values for the rice ingredient profile. Does not contribute to contamination_profile typical/p95 fields.
Wiki pages this source may touch
Verification notes
Source PDF: raw/manual-fetch/seasonal-geographic-variance/auto-fetched/auto-mineral-water-cd-product_2015_10-9755-ejfa-v27i1-17870.pdf. The auto-fetched filename slug (mineral-water-cd-product) is incorrect for this paper — the paper is a rice-Cd plant-science review, not a mineral-water occurrence survey. The slug was assigned upstream by the discover-skill harness against a Cd × product gap query and is preserved in raw_handle: and raw_path: for provenance only; frontmatter matrices:, ingredients:, and products: reflect the actual content (rice, plant-tissue, soil; rice ingredient; no products). No mineral-water content in this paper. Same “mineral-water-cd-product” filename pattern as mostofa2015-rice-h2s-cd-tolerance in this folder.
Evidence tier B reflects the peer-reviewed narrative-review character — substantive Cd-in-rice synthesis with traceable cited primary sources, but no original measurements and no systematic-review methodology. The tier is downgraded from A because all numerical anchors are secondhand; it is held above C because the review is peer-reviewed in an indexed journal and the consolidated source set is correctly attributed to its primary literature.
No brand-attributed contamination data. No HMT&C-program brands named. Discussion of agronomic countermeasures (soil dressing, silicon, phosphorus, zinc, sulfur, chloride, industrial by-products, phytoextraction with sorghum and kenaf) names reagents and methods without vendor brand attribution; nothing to redact under Part 12.
Cadmium is reported throughout as total Cd; no inorganic vs. organo-Cd speciation is performed. This is not a defect — Cd is non-redox and predominantly Cd²⁺ in plant tissue and soil solution under the conditions discussed. Mercury and arsenic speciation flags do not apply (those metals are not the topic).
Tables and figures: Table 1 (QTL analysis of cadmium concentration in rice, p.97) was read in full; the QTL rows are summarised above and were cross-checked against the cited population, marker interval, and reference fields. Figure 1 (p.96, Cd transport schematic) is reproduced from Uraguchi and Fujiwara (2012) and contributes no original data.
Audit subagent (2026-05-30) flagged the >80%-root-Cd attribution as ambiguous between Cui 2004 and Cui 2008; verified against PDF p.96 — Fasahat cites “(Cui et al., 2004; Liu et al., 2007;…)” for the >80% claim, while Cui 2008 is cited only for the adjacent “higher Cd remains in roots” statement. Wiki Key numbers corrected from “Cui et al., 2008” to “Cui et al., 2004” for the >80% figure.
Page history
The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
|---|---|---|
| ddfd414 | 2026-05-30 | ingest: yildirim2021-humic-fulvic-cd-garden-cress fresh from manual-fetch/seasonal-geographic-variance/auto-fetched |