Amelioration of Salt-Induced Damage on Paeonia ostii ‘Fengdan’ by Exogenous Application of Silicon

Abstract

To investigate the amelioration of salt-induced damage on Paeonia ostii ‘Fengdan’ by exogenous silicon, we analyzed the photosynthetic and physiological characteristics of 1.5-year-old ‘Fengdan’ seedlings under NaCl stress by applying exogenous silicon (0, 0.75, and 1.5 mmol/L). Our results showed that the contents of the photosynthetic pigments chlorophyll a, chlorophyll b, and carotene, the transpiration rate, stomatal conductance, and intercellular CO2 were significantly enhanced under salt stress when silicon treatment was applied, implying that the net photosynthetic rate was greatly improved. In addition, the plant height, stem thickness, and above-ground dry biomass of tree peony seedlings were effectively increased under salt stress with low-concentration silicon (0.75 mmol/L) treatment, along with osmotic substance (SS, SP, and Pro) content, total polyamine (TP) contents, and the activities of antioxidant-related enzymes (SOD, POD, and CAT) and polyamine-related synthetases (ADC, ODC, and SAMDC). In the low-concentration silicon treatment, malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anions (O2−) were transformed quickly, which eventually reduced cell oxidative damage and improved seedling tolerance. This is an important finding in the understanding of how exogenous low-concentration silicon can alleviate salt-induced damage and promote the growth of tree peony seedlings, thus providing a new perspective on tree peony cultivation.