Submitted to: Journal of Environmental Toxic Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 15, 1996
Publication Date: N/A
Interpretive Summary: Selenium is a naturally-occurring element associated with many soils in the westside of the San Joaquin Valley of California. Higher than normal concentrations of Se in waterfowl have contributed to an increased frequency of deformities and reproductive disorders in birds frequenting evaporation ponds in the westside. Strategies are not readily available for effective reduction of high Se concentrations in the soil. Presently the Water Management Research Lab is evaluating the ability of plants to extract Se from the soil. Previous studies indicated that the Brassica family absorbs high amounts of Se because of their inability to discriminate between sulfur and selenium. Consequently, several cultivars within the Brassica family were screened in both water and soil culture to find the cultivar that accumulates the highest concentration of Se without exhibiting toxic effects. Our results showed that although physical toxicity symptoms were not observed, Se accumulation, dry matter yield, and total protein did vary amoung the different cultivars. Based upon this type of study, the best Brassica cultivar can be selected and used to lower Se levels in Se-laden soils.
Elevated levels of Se have recently been found in agricultural soils in the westside of the central valley of California. Strategies to lower soil Se levels include irrigation and drainage management and phytoremediation. Phytoremediation studies at the Water Management Research Laboratory demonstrated that Indian mustard (Brassica juncea) lowers soil Se concentrations by its high uptake of Se. A greenhouse study was conducted to evaluate different cultivars of Brassica juncea for both the accumulation of Se and their respective tolerance for high tissue Se content based on total protein, selected free seleno-amino acids, and dry matter yield. Differences in Se uptake by the different Brassica cultivars was studied in 2 mg Se/L - enriched water - and soil culture. Shoot Se concentrations ranged from 501 to 1017 mg Se/kg DM in the different cultivars grown in water culture and from 152 to 332 mg Se/kg in the same cultivars grown in soil culture. Cultivars grown with Se exhibited dry matter (DM) decreases of 12 to 23% compared to the same cultivars grown without Se. There was a significant negative correlation of -0.746 between total protein and shoot Se concentration. Among the free seleno-amino acids tested, seleno methionine was detected in the highest concentration and ranged from 92 to 958 ng/g DM. Based upon these parameters the best Brassica cultivar can be selected for the phytoremediation of Se.