Modulation of Physiological and Biochemical Traits of Two Genotypes of Rosa Damascena Mill. By Nano Silicon Under in Vitro Drought Stress
Abstract Drought is a major abiotic stress that prevents plant growth and efficiency. Silicon increases drought tolerance by regulating the biosynthesis and acumulation of some osmolits.This study was conducted to modulate dought stress induced by Polyethylene glycol (PEG) in two genotypes of damasks by nano silicon dioxide (nSiO2). The experiment included three levels of nSiO2 (0, 50 and 100 mg L-1) and PEG (0, 25, 50, 75 and 100 g L-1) added to culture medium. Drought stress decreased protein content while Maragheh genotype under normal conditios and treating with 100 mg L-1 nSiO2 had the highest protein content. Under severe drought stress Maragheh genotype had stronger membrane stability index (MSI) than Kashan genotype and explants treated with 100 mg L-1 nSiO2 had the highest MSI in control plants. Contrary to the negative effects of drought, plants treated with 100 mg L−1 nSiO2 maintained more of their photosynthetic parameters in comparison with other treatments and showed higher amount of protein and proline in Maragheh rather than kashan genotype. Drought stress reduced the values of Fm, Fv/Fm, and Fv. In general, under drought stress, treatment with nSiO2 increased the mentioned characteristics before. It also improved water deficit tolerance through enhancing in the activity of antioxidant enzymes such as catalase, peroxidase, guaiacol peroxidase and superoxide dismutase while the amount of lipid peroxidation and hydrogen peroxide decreased. The results showed that Maragheh genotype may be more stronger in counter with water deficit by improving in water balance, antioxidant enzyme activities, and membrane stability.