Effect of Silicon Foliar Application on Morpho-Physiologycal Characteristics and Antioxidant Activity of Wheat under Limited Irrigation Conditions

Water stress is the most important abiotic stress in crop production. Silicium (Si) is the second most abundant element in the soil with beneficial effects on plant tolerance to biotic and abiotic stresses. In order to evaluate the effect of this element in increasing tolerance to water deficit in wheat, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. Treatments included four wheat cultivars, Shiraz, Sirvan, Ofogh, Baharan, foliar silicon application in two-levels, zero (control), and 3 mM, and three levels of water deficit (field capacity, 40% and 60% of field capacity). The results showed that water deficit reduced spike length (31%), dry matter per plant (41%), grain yield (25%), greenness index (11%), flag leaf relative water content (24%), catalase (24%), peroxidase (70%) and superoxide dismutase activity (41%). Baharan and Sirvan cultivars were superior for greenness index and peroxidase activity. However, foliar silicon application at 3 mM concentration ameliorated the negative impacts of water deficit stress. Foliar application of silicon enhanced all the above parameters including antioxidants. For a majority of the measured characteristics, it was evident that Baharan and Sirvan, as water deficit tolerant cultivars, and Ofogh, were superior compared to Shiraz cultivar. The results showed that foliar application of silicon increased the activity of antioxidant enzymes and as a result ameliorated the negative impacts of water stress.