Plant availability of selenite and selenate as influenced by the competing ions phosphate and sulfate

摘要: The relative plant availability of selenate versus selenite depends on the concentrations competing ions, specifically sulfate and phosphate, respectively. In solution culture, concentration phosphate is typically 100- to 1000-fold greater than in soil solution, an artifact that could lead underestimation phytoavailability selenite. A nutrient study was conducted compare perennial ryegrass (Lolium perenne L. cv. Evening Shade) strawberry clover (Trifolium fragiferrum O'Conner) at basal SO4 (0.5 mM) PO4 (2 μM) similar those found solution. Concentrations up 5 mM 200 μM allowed quantitative comparison efficacy ions. both species, more phytotoxic selenate, especially for shoot growth. Selenate less toxic, tended preferentially inhibit root Translocation percentages were much higher with (≥84%) (≤47%). 10-fold increase decreased uptake from by >90% species. ryegrass, increases caused 30% 50% decreases Se accumulation selenite, but such only occurred roots. Sulfate-selenate antagonisms thus stronger phosphate-selenite antagonisms. Nonetheless, conventional solutions millimolar will significantly underestimate moderate levels salinity can sufficiently reverse apparent two forms Se.