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Sodium-silicate and calcium-silicate differentially affect silicon and aluminium uptake, antioxidant performance and phenolics metabolism of ryegrass in an acid Andisol
Current evidence indicates that silicon (Si) alleviates diverse stresses by improving plants’ antioxidant capacity and phenolics metabolism. We assessed the effect of sodium (Na)-silicate (Na2SiO3) and calcium (Ca)-silicate (CaSiO3) on Si and aluminium (Al) uptake, antioxidant performance and phenolics (with antioxidant or structural function) of ryegrass cultivated on an acid Andisol under greenhouse conditions. Ryegrass was treated with either Na-silicate or Ca-silicate at gradually increasing doses (250, 500 and 1000 mg Si kg-1 soil). Yield, Si and Al concentrations were measured in roots and two shoot cuts. At the first cut, phenols, antioxidant enzymes, antioxidant capacity, lipid peroxidation and lignin production/composition were also determined. Na-silicate supplied ryegrass exhibited the highest Si content. Root Si was closely correlated with Al or Si/Al ratio. Shoot Si uptake increased total phenols and antioxidant enzyme (CAT, APX and POD) activities, but it reduced lipid peroxidation. Silicon also changed the lignin production/composition in shoots at the highest Na-silicate dose. Silicon uptake reduced the deleterious effect of soil acidity in ryegrass. Na-silicate had the highest influence on the antioxidant system through the enhancement of phenols production and antioxidant enzymes activation. Peroxidase activity appears to be associated with increased lignin biosynthesis in Na-silicate supplied plants.
CP17202 Accepted 21 November 2017
© CSIRO 2017