Effects of glyphosate on uptake, translocation, and intracellular localization of metal cations in soybean ( Glycine max) seedlings

Root-fed or foliar-applied glyphosate [ N-(phosphonomethyl) glycine] reduced uptake and translocation of Ca 2+ and Mg 2+, but not K +, by soybean [ Glycine max (L.) Merr. “Hill”] seedlings as measured by atomic absorption spectrometry. Histochemical techniques revealed that cells of secondary roots that were formed after glyphosate treatment were deficient in Ca 2+. The relative distribution of Ca 2+ in control root and leaf cells was mitochondria > plastids > cytoplasm. Glyphosate severely reduced Ca 2+ content and eliminated intracellular concentration of Ca 2+ in the mitochondria of both root and leaf cells. Glyphosate had no effects on K + distribution at the ultrastructural level. These results support the view that glyphosate effects on distribution of divalent metal cations may be related directly or indirectly to the phytotoxicity of the herbicide.