Abstract:

Investigating the absorption, utilization, and transformation of different forms of selenium by crops is of great significance for the development of new and efficient selenium-enriched agricultural techniques. In this study, we used excised pear tree leaves to explore the absorption, utilization, antioxidant response, and the influence of two accompanying anions, silicate (SiO₃^3-) and sulfate (SO₄^2-), on three forms of selenium: sodium selenite (Na₂SeO₃), sodium selenate (Na₂SeO₄), and selenomethionine (SeMet). The results showed that after treatment with the three forms of selenium (SeO₃^2-, SeMet, SeO₄^2-), the average selenium contents in the excised leaves were 7.89, 0.20 and 0.14 mg/kg, respectively. Obviously, the absorption of SeO₃^2- form was much greater than that of SeMet and SeO₄^2- forms. The higher the selenium addition concentration, the higher the selenium content in the leaves. Two accompanying anions had no impact on SeO₃^2- absorption. But SiO₃^2- tended to boost SeO₄^2- and SeMet uptake. At 500 μmol/L SeO₄^2-, leaf Se content rose 19.90% vs control; at 50 μmol/L SeMet, it jumped 170.00% vs control. SO₄^2- cut SeO₄^2- uptake by 59.89% at 500 μmol/L vs control，but hiked SeMet uptake by 102.38% at 50 μmol/L vs control. All three forms of selenium reduced the activity of superoxide dismutase (SOD) and peroxidase (POD), while increasing the activity of catalase (CAT) and the content of reduced glutathione (GSH) in the leaves. Additionally, low concentrations of SeO₃^2- and SeO₄^2- treatments reduced the content of malondialdehyde (MDA). The results of this study indicate that SeO₃^2- is the preferred form of selenium for absorption by pear tree leaves.

Key words: selenium forms, absorption, antioxidant response, accompanying ions, excised leaves, foliar fertilizer, fruit trees, selenium-enriched agricultural products