Silicon mitigates potassium deficiency in Hordeum vulgare by improving growth and photosynthetic activity but not through polyphenol accumulation and the related antioxidant potential

Aims Potassium (K + ) deficiency is one of the most abiotic constraints reducing plant growth and productivity. The use of silicon (Si) has been reported to alleviate abiotic stresses in plants. However, data regarding the roles played by this element in mediating K + deficiency are still scarce. Therefore, the present work was carried out to investigate the possible involvement of Si in mitigating the negative impact of K + deficiency on cultivated barley Hordeum vulgare L. (var. Rihane). Methods Plants were hydroponically grown either under K + sufficient nutrient solution containing 3 mM K + or in K + -deficient medium containing 10 µM K + without or with Si (1 mM). Shoot growth, shoot water content, leaf osmotic potential, shoot K + concentration, photosynthetic activity, chlorophyll fluorescence, soluble sugar concentrations, and shoot phenolic compound contents and their antioxidant properties were determined. Results Results showed that shoot growth, shoot K + concentration, and gaseous exchange were reduced by K + deficiency. Photosynthesis decrease was mainly linked to sugar accumulation in leaves. Except for K + concentration, a beneficial effect of Si was observed. A modulation in the accumulation of polyphenols and their antioxidant capacities has been observed. Conclusions Overall, the data indicate that the beneficial effects of Si on barley plants grown under K + deficient medium were mainly due to increased growth and photosynthetic activity but not through an improvement of shoot K + concentration and phenolic compound accumulation and related antioxidant capacity suggesting a possible use of Si as a fertilizer to correct the deleterious effects of nutritional stress.