| A pot experiment, which simulated the natural growth environment, was conducted to investigate whether exogenous γ-aminobutyric acid (GABA) could alleviate salt damage to ground cover plant Orychophragmus violaceus. Under the stress of 50 mmol·L-1 NaCl solution, different concentration gradients of γ-aminobutyric acid treatment solution (0.2, 0.4, 0.8, and 1.6 mmol·L-1) were applied to the seedlings of O. violaceus. Morphological indexes (root length, plant height, leaf width, and stem diameter) and physiological indexes (contents of chlorophyll, soluble protein, and MDA, and activities of SOD and POD) were measured on the 5th, 10th, and 15th days of the experiment. Meanwhile, the cell structure of O. violaceus seedlings was observed by paraffin section technique, and the effect of exogenous application of GABA on the growth and physiology of O. violaceus seedlings under salt stress was investigated. The results showed that with the increase of exogenous GABA concentration, under different treatment days, the growth indictors of the seadlings showed a trend of increasing first and then decreasing. The net growth production of the plant height, leaf width, and stem diameter of O. violaceus were the highest under 0.4 mmol·L-1 GABA treatment, with an increase of 73.63%, 66.55%, and 6.83%, respectively, and the MDA content was the lowest at 2.66 nmol·g-1. The 0.4 mmol·L-1 GABA treatment made the soluble protein content, POD activity, SOD activity, and chlorophyll content of O. violaceus the highest, which were 17.34 mg·g-1, 103.03 U·g-1·min-1, 338.75 nmol·g-1, and 54.3 (SPAD value), respectively. |