Zhao et al. 2023 — Exogenous silicon reduces cadmium in rice
This study evaluated the effect of foliar silicon (Si) application on cadmium accumulation in brown rice under pot-experiment conditions with Cd-contaminated soil. Silicon spraying reduced brown rice Cd concentrations by 13.5 to 65.7 percent depending on rice variety, with the reduction associated with enhanced phenylpropanoid pathway metabolism that promotes cell wall lignification and restricts Cd translocation from roots to grain. The authors identified Si-induced upregulation of PAL, C4H, and 4CL genes as mechanistic drivers of reduced Cd transfer to edible grain tissues.
Key numbers
- Brown rice Cd reduction range: 13.5–65.7% across tested rice varieties with Si foliar spray
- Soil Cd treatment levels: 1.0 and 2.0 mg/kg (wet weight basis not stated; pot experiment with amended soil)
- Brown rice Cd control concentrations not individually tabulated in abstract; reduction magnitudes extracted per variety
- Phenylpropanoid enzyme activities (PAL, C4H, 4CL) significantly elevated in Si-treated plants
Methods (brief)
Pot experiment with Cd-spiked soil and multiple rice varieties; foliar Si spray applied at defined growth stages. Brown rice Cd analyzed by ICP method (speciation not stated; total Cd reported). Gene expression by qRT-PCR; enzyme activities by spectrophotometric assays.
Implications
Certification: Si application is a documented agronomic lever for reducing Cd in brown rice by 14–66%; relevant to supply-chain mitigation guidance for rice protein and brown rice ingredients. Courses: Illustrates the processing/agronomic mitigation lever with quantified magnitude. App: Supports flagging brown rice as higher-risk variant versus Si-treated or white rice derivatives.