Abstract: In order to investigate the resistance and adaptation mechanism of Primula forbesii to salt (NaCl) stress, a pot experiment was conducted to determine the growth and physiological characteristics of P. forbesii under NaCl concentrations of 0, 50, 100, 150, 200, and 250 mmol·L^-1. It was found that: 1) Along the concentration gradient of NaCl, the growth of P. forbesii showed low-concentration promotion and high-concentration suppression effects. At higher NaCl concentrations, plants showed stress symptoms in that plant height, crown width, leaf area, and above-ground and underground dry weight, and leaf water content were significantly decreased. Meanwhile, the relative electrical conductivity was significantly increased. 2) The leaf net photosynthetic rate, intercellular CO₂ concentration, transpiration rate, stomatal conductance, soluble protein, free proline, soluble sugar, and the activities of superoxide dismutase, peroxidase and catalase all rose with increasing NaCl concentration and then decreased at higher concentration. Malondialdehyde content displayed continuous increase across the concentration range tested, indicating that the photosynthetic system, cell osmotic regulation and antioxidant enzyme system of plants had positive response strategies to NaCl stress. 3) Higher NaCl concentrations significantly increased the Na⁺ content in leaves, petioles and roots of the plants, with the largest increase of Na⁺ content in roots. With increasing NaCl concentration, the contents of K⁺ and Ca²⁺ in plant organs other than leaves showed a trend of initial increase and later decrease while the contents of K⁺ and Ca²⁺ in leaves remained relatively high at higher NaCl concentrations. In summary, P. forbesii has moderate salt tolerance and is a potential flower species for saline soil garden applications. In this experiment a low NaCl concentration of 50 mmol·L^-1 promoted the growth of P. forbesii, but the growth and development of plants were inhibited when the concentration of NaCl was equal to or greater than 150 mmol·L^-1.

Key words: Primula forbesii, NaCl, gas exchange parameters, osmotic regulation, active oxygen metabolism, ion transport