Beneficial effects of silicon on growth, nutrient dynamics, and antioxidative response in barley (Hordeum vulgare L.) plants under potassium deficiency

The present work evaluates the role of silicon (Si) in barley (Hordeum vulgare L. var. Rihane) plants subjected to potassium (K+) deficiency. Plants were grown hydroponically either under K+ -sufficient (+ K, 3 mM) or K+-deficient (-K, 10 mu M) conditions supplied or not with 1 mM Si. Several parameters were determined in both shoots and roots [growth, macronutrients (K and Ca) and micronutrients (Fe and Zn) dynamics, protein and malondialdehyde (MDA) contents, and antioxidative enzymes activities (superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPX)]. Results showed that K+ deficiency resulted in a reduction of growth and K+ concentration in both shoots and roots compared to control plants. The exogenous application of Si alleviated the reduction of plant growth induced by K+ deficiency but did not influence K+ nutrition. Concerning Ca, Fe, and Fe nutrients, the addition of Si adjusts their uptake, translocation, and use efficiencies. Leaf MDA concentration was not affected by K+ deficiency, while an increase was noted in roots. The increase of root MDA concentration was mitigated by the addition of Si. Modulation of antioxidant enzyme activities was also observed. As a whole, the data indicate the beneficial effects of Si on barley plants grown under a K+-deficient medium by modulating mineral nutrition and antioxidative response. This suggests the possible use of Si as an effective, cheap, and environmentally safe fertilizer to improve the plant's response to K+ deficiency.