Silicon Mitigates the Adverse Effect of Drought in Canola (Brassica napusl.) Through Promoting the Physiological and Antioxidants Activity

Abstract

Drought is the major limiting factor for crops which reduces the growth and ultimately yield. However, silicon (Si) is considered one of the important elements for ameliorating adverse effect of abiotic stresses including drought also. To re-establish the previous evidence of Si, an experiment was carried out in a wire-house under pot-culture, where canola plants were grown under normal conditions (100% field capacity) and water deficit condition (40% field capacity). To know the ameliorative effect of silicon on drought-induced canola plants through promoting the physiological, growth, biochemical, and yield attributes of canola (Brassica napusL.); exogenous application of Si was done by two different methods i.e., through seed treatment (priming) before sowing and foliar spray at vegetative stage. For priming, seeds of canola were dipped for six hours in a 5 mM Si solution, whereas for foliar spray, three different levels of Si i.e., 2, 4 and 6 mM Si solution were applied at vegetative stage (after 40 days of seed emergence). Drought stress caused a substantial decrease in the parameters of water relations, and the uptake of various nutrients in canola plants. However, the application of Si significantly improved plants' ability to withstand the drought stress through enhancing the uptake of Si in plants and also enhanced the activity of ascorbate peroxidase (APX), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT). Data on, water potential, leaf water contents ratio and leaf pigments, (for example, chlorophylla, chlorophyllb, total chlorophyll, carotenoids), was positively influenced by applying Si under water deficit stress. Similarly, agronomic parameters such as seeds pod(-1), seed weight and seed yield were also enhanced as a result of the Si application under drought condition. Among these application methods of Si, the foliar spray has been found more effective for alleviating the adverse effects of water deficit stress on canola plants. Therefore, the results of the present study revealed that foliar application of Si at the vegetative stage may be useful for ameliorating the adverse effect of drought; since Si promoted to maintain turgor pressure, antioxidants activity in plants and also improved the nutrient accumulation both under water stress and control condition.