This field study grew broccoli, three cabbage types and Swiss chard on saline soils of the western San Joaquin Valley that are naturally high in boron and selenium. Its focus is selenium biofortification, but it reports boron in the soil water extract and in the harvested plant tissue. All five crops tolerated the conditions and accumulated boron at 152 to 239 mg/kg dry matter (crop means).
Key numbers
- Soil (0 to 60 cm): soluble boron 7.9 ± 5.3 mg/L in the soil water extract (Section 2, p. 2).
- Soil soluble boron by crop bed and depth ranged from 2 to 20 mg/L (Table 1, p. 3).
- Plant tissue boron, mean (SD), mg/kg dry matter: broccoli 228 (36), n = 12; green cabbage 239 (37), n = 4; red cabbage 152 (56), n = 4; savoy cabbage 169 (54), n = 6; Swiss chard 186 (62), n = 6 (Table 3, p. 5; n from Methods, p. 3).
- Irrigation water contained boron below 1 mg/L (Section 2, p. 2).
Methods (brief)
Seedlings were transplanted onto a saline field site and sprinkler-irrigated with good-quality water without fertilizer; after 86 days, five plants per sampling site were bulked into composite samples. Plant material was washed, dried at 50 °C and ground; macro and micro elements were measured by ICP-OES (Varian Vista-Pro), and selenium species by HPLC-ICP-MS.
Evidence fitness
Supports boron concentrations in edible vegetables grown on naturally high-boron saline soils. It does not support typical market concentrations, dietary boron intake, or health effects; the dietary comparison in the paper does not evaluate boron.
Limitations
One field site and season; boron results are reported only as tissue means without a separate boron quality-control description. Plants are reported as dry matter, not as eaten. USDA authors; no competing interests declared.
Related evidence
Update history
No substantive edit history is available in this build. The full commit record is available in git.