Silicon (Si) Seed Priming Improves Growth and Photosynthetic Efficiency of Barley Plants Under Salt Stress in Agricultural Field Conditions

Silicon (Si) application has been recognized as a recent ecological approach for overcoming the negative effects of high soil salinity and enhancing salinity stress responses in plants. The present study was conducted in order to investigate in which extent Si seed priming can improve growth and photosynthetic activity in barley (Hordeum vulgare L.), cultivated under field saline conditions. Unprimed and primed seeds with 20, 40, and 60 mM sodium silicate were then sown in the agricultural field. Our results showed that for all used Si concentrations, seed priming enhanced the whole plant length (about 40%), increased shoot and root dry weight by about 5.4-fold and fourfold respectively. It also resulted in a higher photosynthetic pigment level, an enhanced photosynthetic gas exchange, a better stability of the photosystems, a stimulation of photosystem oxidation, and a mitigation of nonphotochemical energy dissipation. Priming with 20 mM Si induced the highest reduction in hydrogen peroxide (H2O2) levels in shoots by 52% and in roots a reduction by 92% was observed in 60 mM Si, followed by a reduction of 90% in 20 mM Si. Regardless of the Si concentration used, priming reduced malondialdehyde (MDA) levels in both shoots and roots, by about 50% and 87% respectively. The overall enhancement in photosynthetic attributes of primed plants ultimately increases considerably (about 5 times) plant growth and productivity. In conclusion, using Si in seed priming of barley plants is an effective, easy, and low-cost method, especially for farmers, to increase their plant productivity in salt-affected agricultural lands.