Selenium desorption in tropical soils by sulfate and phosphate, and selenium biofortification of Mombaça grass under increasing rates of phosphate fertilisation

Abstract

Selenium (Se) is essential for animals and humans, and studies assessing the influence of sulfur (S) and phosphorus (P) on Se availability and biofortification in tropical soils are required. This study evaluated the adsorption of selenate (SeVI) and selenite (SeIV) in two oxidic soils with contrasting soil texture and assessed effects of phosphate and sulfate as competitive anions on Se desorption. The study also examined Se biofortification of Panicum maximum cv. Mombaça grown in Se-treated clayey soil under increasing rates of P fertilisation. In the laboratory, different Se concentrations were added to soils for adsorption studies (0, 1, 2, 4 mg L–1 for SeVI and 0, 4, 8, 16 mg L–1 for SeIV), with Se desorption performed by adding different concentrations of P (0, 2.18, 4.36, 10.90, 21.90 mg L–1) or S (0, 3.75, 7.5, 15, 30 mg L–1). Mombaça grass was grown in pots for 43 days in the clayey soil fertilised with SeVI and increasing P rates. Selenium adsorption varied depending on Se speciation, Se rate and soil texture, with SeIV showing greater adsorption than SeVI. In general, amounts of SeVI desorbed increased with increasing addition of P and (mainly) S. However, only P had a positive effect for releasing SeIV from soils. At all SeVI rates added in the clayey soil, Se contents in the shoot dry matter of Mombaça grass increased with increasing P fertilisation rate, agreeing with the desorption results. Further studies combining desorption with biofortification data are recommended for assessing the influence of P in sandy clay loam tropical soils.

Selenium uptake, translocation, subcellular distribution and speciation in winter wheat in response to phosphorus application combined with three types of selenium fertilizer

“…P starvation had no effect on selenate uptake but decreased selenate concentration in the xylem sap of selenate-treated plants in hydroponic experiments [ 11 ]. Some studies reported that P application increased the utilization of selenate and then increased the Se contents in plants [ 29 , 30 ]. Compared with the numerous studies on inorganic Se, few studies have focused on the uptake of organic Se influenced by P application in plants.…”

Selenium Application Provides Nutritional and Metabolic Benefits to Wheat Plants

“…Liu et al [47] demonstrated that P and Se absorption in the form of selenite presents antagonistic behavior, in which the increase in the P supply significantly decreased the Se concentration in the roots, stems, and leaves of winter wheat, justifying that the presence of P and S influences Se bioavailability in various plant tissues. However, Santos et al [48] and Zhang et al [49] observed in Panicum maximum cv. Mombaça and wheat plants, respectively, that the way Se is present in the soil influences the synergism with P, i.e., there is an accumulation of both elements only when Se is applied as selenate.…”

Selenium biofortification of soybean genotypes in a tropical soil via Se-enriched phosphate fertilizers

“…The average Se content found in the studied soil (0.73 mg dm −3 ) is within the range of Se contents reported for soils of the State of São Paulo (where the Uva farm is located), which varies from <0.08–1.61 mg dm −3 . Soil Se content is influenced by characteristics such as pH ( Schiavon et al, 2020 ), presence of competing ions such as sulfate and phosphate ( Lessa et al, 2016 ; Santos et al, 2022 ), soil texture ( Araujo et al, 2018 ), organic matter ( Li et al, 2017 ), and presence of microorganisms ( Gregorio et al, 2006 ).…”