Feng et al. 2023 - Rice seedling cadmium and salt uptake under temperature and CO2 shifts

Feng and colleagues exposed rice seedlings to cadmium, sodium chloride, and combined cadmium-plus-sodium stress under two temperatures and three CO2 levels. The study is supply-chain and plant-uptake mechanism evidence for rice cultivation stressors, not market occurrence evidence for rice grain, salt, or finished foods.

Key numbers

The experiment used Oryza sativa L. cv. XZX 45 seedlings grown for 16 days, acclimated in modified ISO 8692 nutrient solution, then exposed for 3 days. Temperature/CO2 conditions were 23 C or 27 C crossed with 360 ppm, 450 ppm, or 700 ppm CO2. Relative humidity was 60 +/- 2%, and the chamber CO2 resolution was 1 ppm.

Exposure solutions were:

The preliminary inhibition-rate test used nominal Cd concentrations of 0, 0.25, 0.50, 1.00, 2.00, 4.00, and 8.00 mg Cd/L and Na concentrations of 0, 0.1, 0.3, 0.5, 0.9, 1.2, and 1.6 g Na/L. EC values based on relative-growth-rate inhibition were EC20 = 0.14 mg Cd/L, EC50 = 1.81 mg Cd/L, and EC75 = 5.66 mg Cd/L for Cd; and EC20 = 0.2 g Na/L, EC50 = 0.64 g Na/L, and EC75 = 1.08 g Na/L for Na.

For relative growth rate, the source reports these ranges under 23 C and 27 C for ambient/medium/high CO2 treatments:

The authors state that growth was significantly better at 27 C and at higher CO2. Approximately 25%, 50%, and 75% growth inhibition corresponded to Na treatments of 0.2, 0.6, and 1.1 g/L and Cd treatments of 0.2, 1.8, and 5.4 mg/L.

Measured Cd concentrations in rice shoots and roots were reported as ug/g dry weight:

The source reports that Cd concentrations were much lower in shoots than roots. Root Cd concentrations tended to be higher under Cd-only exposure than under Cd+Na exposure, and root Cd was highest at 450 ppm CO2.

Measured Na concentrations were reported as ug/g dry weight. At 23 C and 360 ppm CO2, Na-only shoots ranged 3011.61-11655.06 and roots 7569.71-12545.83; Cd+Na shoots ranged 2813.51-11340.46 and roots 7453.15-12805.63. At 23 C and 450 ppm CO2, Na-only shoots ranged 2568.85-8641.81 and roots 5500.33-10866.99; Cd+Na shoots ranged 2220.49-8589.50 and roots 6425.30-10252.57. At 23 C and 700 ppm CO2, Na-only shoots ranged 2257.15-6848.62 and roots 5067.89-9131.93; Cd+Na shoots ranged 1825.34-5020.30 and roots 6657.62-9354.65.

The text then reports the second temperature block with the same T1 label, but context indicates this is the 27 C block. Under that block, Na-only shoots ranged 4004.82-13243.01 and roots 8057.37-14898.06 at 360 ppm CO2; Cd+Na shoots ranged 2006.02-10301.83 and roots 3867.43-13083.43. At 450 ppm CO2, Na-only shoots ranged 2607.55-9115.69 and roots 6500.54-8351.60; Cd+Na shoots ranged 2457.76-8309.92 and roots 6459.82-12013.72. At 700 ppm CO2, Na-only shoots ranged 2635.73-8979.19 and roots 5062.06-8811.56; Cd+Na shoots ranged 2187.13-7068.07 and roots 4223.16-7396.10.

The authors summarize that Na concentrations were generally higher in roots than shoots, maximum Na reached about 15 mg/g dry weight in roots and more than 12 mg/g dry weight in shoots, and Na concentrations tended to be lower at high CO2.

Methods (brief)

Rice seedlings were exposed in 50 mL Erlenmeyer flasks containing 50 mL of Cd, Na, or combined Cd+Na solution. After 3 days, seedlings were rinsed with distilled water, held in MES-Tris buffer with CaCl2 for 4 hours to remove surface/apparent-free-space ions, separated into shoots and roots, dried, digested with HNO3-HClO4 (4:1), and analyzed for total Cd and Na by ICP-AES using a PerkinElmer Optima 700 DV. Relative growth rate was calculated from initial and final fresh weights. Statistical comparisons used ANOVA and Tukey’s multiple range test at alpha = 0.01 or 0.05.

Implications

Certification: Do not use the seedling-root or seedling-shoot Cd/Na values as rice grain occurrence data or salt occurrence data. These are controlled hydroponic exposure endpoints from spiked nutrient solutions.

Courses: Useful for supply-chain and agronomic education on how salinity, Cd contamination, temperature, and CO2 can jointly affect uptake/translocation in rice seedlings. It also illustrates why root/vegetative-tissue uptake cannot be silently substituted for edible grain concentrations.

App: Context only for rice supply-chain risk explanation. The paper does not provide consumer-product or ingredient concentration values for rice grain.

Wiki pages this source may touch

• rice
• agronomic
• cadmium
• index

Verification notes

The auto-fetch filename framed this as salt/cadmium. The PDF measures Cd and Na uptake in rice seedlings under controlled climate and hydroponic stress, not heavy metals in market salt. Products are intentionally empty. ingredients includes rice because the source directly uses Oryza sativa seedlings and informs rice supply-chain uptake mechanisms, but the page repeatedly marks the data as non-occurrence and non-grain.

The extracted text renders some plant-tissue concentration units as mg/g DW, but Figure 2 and Figure 3 captions specify ug/g dry weight; the reported Na narrative maximum of about 15 mg/g is consistent with 14898.06 ug/g rather than 14898.06 mg/g. Values above are therefore recorded as ug/g dry weight for Cd and Na tissue ranges, with the source’s own mg/g summary retained only where the authors explicitly express the maximum in mg/g.

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.