Effects of Exogenous Silicic (Si) and Salicylic acid (SA) Applied Individually or in Combination on Barley Growth and Nitrogen Uptake under Various Watering Regimes

This pot experiment investigated the effect of treatment with exogenous silicic (Si) and/or salicylic acids (SA) on dry matter (DM), nitrogen yield (NY) and soil N uptake from soil (Ndfs) and from fertilizer (Ndff) nitrogen use efficiency (%NUE) of barley plants (Hordeum vulgare L.) grown under varying levels of watering regimes (high stress I1, mild stress I2 and well-watered I3). Results showed that, foliar application of Si and/or SA markedly improved the overall studied growth parameters of barley plants and decreased the water-deficit influences. The synergistic effects of Si + SA application were more effective as compared with Si or SA applied separately indicating that Si and SA supports each other’s in improving plant performance which was more pronounced under high water-deficit than other watering regimes. A proper application of Si and SA might represent a suitable agricultural approach and result in increased production of barley, particularly, in the semi-arid areas under rain-fed conditions.