Improving the Yield and Physiological Traits of Different Safflower Cultivars (Carthamus tinctorius L.) Using Silicon and Nickel Foliar Application in a Saline Soil Condition

Improving the yield of different safflower cultivars using silicon and nickel foliar application in a saline soil condition was the hypothesis proposed in this research. For this purpose, a factorial experiment was conducted in the form of a randomized complete block design in Haji Abad, Iran, in 2019 and 2020. The first factor included four cultivars of safflower including Sofeh, Isfahan, Padideh and Golmehr, and the second factor was seven foliar spraying treatments, consisted of control, nickel with concentrations of 100, 200, and 300 mg L⁻¹ and silicon with concentrations of 100, 150, and 200 mg L⁻¹. Results showed that silicon foliar application of 150 and 200 mg L⁻¹ increased potassium content by 10 and 16%, respectively, in compared to the control. Nickel foliar spraying of 300 mg L⁻¹ caused an increase in leaf ion leakage and a decrease in photosynthetic pigments. On the other hand, silicon foliar application of 200 mg L⁻¹ increased the total leaf chlorophyll content by 12 and 18% in Sofeh and Isfahan cultivars, respectively. Compared to the control, silicon with the concentration of 200 mg L⁻¹ caused a 10 and 13% decrease in soluble carbohydrate and proline, respectively. In Isfahan and Padideh cultivars, silicon foliar spraying of 150 and 200 mg L⁻¹ increased the seed yield by 21 and 15% compared to the control. The results of this research showed a positive effect of silicon foliar spraying especially with concentrations of 150 and 200 mg L⁻¹ on improving seed yield and oil percentage in different safflower cultivars under salt stress.