Water Stress Alleviation of Roselle Plant by Silicon Treatment Through Some Physiological and Biochemical Responses

A research trial was planned to find out the effect of water deficit and/or silicon (Si) foliar application on the growth, yield, sepal quality and some physiological characters of roselle plants. Under water stress treatment, the growth parameters (plant height, branch number, dry weight and leaf area) sepal yield and relative water content (RWC) were significantly reduced; however Si treatment ameliorated the negative effects of water stress and improved the growth even with non-stressed plants. The contents of N, P, K, Ca and Mg were significantly decreased in water stressed plants relative to plants grown under higher water levels. Si application increased the contents of N, P, K and Mg, while Ca content was decreased due to Si treatment in stressed or non-stressed plants. Water stress significantly decreased the total soluble solids and pH value however; Si application substantially alleviated this reduction. In contrast, the anthocyanin content was significantly increased due to water stress treatment. Otherwise, Si application increased anthocyanin content in stressed or non-stressed plants. Water stress significantly decreased the chlorophyll content and membrane stability index (MSI) compared with non-stressed plants. However, Si application had positive effects in this respect and alleviated the adverse effects of water stress. The total soluble sugars and proline content were significantly increased under water stress conditions and/or Si application. Water stress treatment promoted the activities of CAT, SOD and POD enzymes in roselle leaves however; Si application increased the activities of those enzymes except POD that decreased.