Interactive effect of lithium on concentration of alkali cations in sugar beet (Beta vulgaris L.) under saline conditions

Abstract

Background and aims Increasing demand for lithium (Li+) for portable energy storage is leading to a global risk of Li+ pollution from the manufacture, use, and disposal of Li+‐containing products. Although Li+, a reactive alkali metal, has no essential function in plants, they readily take it up and accumulate it in large amounts in their tissues. The underlying mechanisms for this Li+ uptake and accumulation are, however, not well described. Our aim has been to investigate the effects of other alkali metals with similar physicochemical properties on the uptake, accumulation, and toxicity of Li+ at low and high osmolarity. Methods To determine the way in which Li+ affects the accumulation of other cations under saline conditions, sugar beet plants were grown in hydroponic culture with equimolar amounts of Li+, potassium (K+), and sodium (Na+) at low and high concentrations in various combinations. Results Sugar beet plants tolerated high Li+ concentrations in the leaf and petiole. Low Li+ concentrations had no impact on plant growth but induced stomata closure. The presence of other monovalent cations at equimolar concentrations did not affect Li+ accumulation, but Li+ application altered the ratio of monovalent and divalent cations in leaves. Plants treated with high Li+ in combination with Na+ or K+ showed reduced plant growth and leaf necrosis, indicating the severe stress caused by Li+ toxicity. Conclusion The presence of cations with similar physicochemical properties to those of Li+ cannot mitigate its toxicity.

Sodium substitutes potassium requirements of sugar beet under saline–sodic conditions

“…Sugar beet was grown under saline–sodic conditions; this reflects high ion (Na and K) accumulation in green parts of plants (leaves) as compared to roots (Table 3). This also shows the salt resistance mechanism maintains the osmotic adjustments using these ions under saline–sodic conditions (Behr & Zörb 2023). That is why sugar beet leaves impart a clear picture of K substitution by Na owing to ion translocation from roots to leaves.…”