Water shortage reduces silicon uptake in barley leaves

Silicon is an increasingly important element in agriculture due to benefits on plant growth and development under stress conditions. Silicon uptake is facilitated by transpiration flow, while plant resistance to drought and ultraviolet radiation are positively related. Thus, we hypothesised that water shortage in barley (Hordeum vulgare L.) will hinder uptake of silicon, and possibly other elements, and that reduced ambient ultraviolet radiation will worsen these negative effects of water shortage. Barley plants were exposed to favourable and reduced water availability during growth under ambient and reduced ultraviolet exposure. Element composition and morphological, biochemical, physiological, and optical traits of barley leaves growing under these four treatments were investigated. Water shortage affected the element composition of barley plants significantly. Silicon and chlorine levels were the most reduced by water shortage, followed by calcium, phosphorus, and sulphur, while potassium levels were not affected. Ultraviolet radiation did not have any significant effects on uptake of elements. These plants did not undergo water shortage stress, as photochemical efficiency of photosystem II and pigment contents were similar across all treatments. Water shortage affected reflectance of light across the whole spectrum, while ultraviolet radiation affected optical properties of the barley leaves in the UV region only.