Silicon Can Alleviate Toxic Effect of NaCl Stress by Improving K+ and Si Uptake, Photosynthetic Efficiency with Reduced Na+ Toxicity in Barley (Hordeum vulgare L.)

Silicon (Si) has not been accepted as an essential element; although its beneficial role in plants against abiotic and biotic stresses is well known. In this regard an experiment was designed to optimize suitable Si dose among four different concentration (control, 100, 200 and 300 ppm) applied via rooting medium as soil treatment under saline (200 mM NaCl) and non-saline growing conditions in four barley genotypes (B-9006, B-15,002, Jou-87 and 14,003). It has been observed that imposition of salinity stress (200 mM NaCl) considerably reduced growth, photosynthetic pigments (Chl-a, Chl-b, total Chl. and carotenoids), leaf relative water contents, Si and K+ contents while Na+ and total soluble protein contents were remarkably enhanced. Alternatively, the rooting application of different concentrations of Si improved growth by enhancing synthesis of photosynthetic pigments and increasing K+ contents while reducing Na+ constituents in roots and leaves of barley plants grown under salinity stress. Furthermore, a negative correlation analysis was found among leaf and root Si contents with leaf and root Na+ contents among barley genotypes under salinity stress. The results also revealed that among all Si levels, 200 ppm Si dose proved to be the best for amelioration of salinity (200 mM NaCl) stress in barley crop.