Salicylic acid (SA) plays an important role in regulating salt stress tolerance in plants. However, there are no studies on the effect of exogenous SA on Saponaria officinalis under salt stress. To study the effectiveness of SA on mitigating salt stress, S. officinalis were used in a pot experiment of salt stress simulated with an NaCl solution (100, 200, and 300 mmol L−1), while an SA solution (0, 0.2, 0.4, 0.6, 0.8, 1.0 mmol L−1) was sprayed on leaves. Under salt stress, spraying SA caused an increase in the salt damage index, electrolyte leakage, and a reduction in malondialdehyde and Na+ content, but an increase in the rate of photosynthesis, chlorophyll, soluble sugar, soluble protein, free proline, K+, Mg2+, Ca2+ content, the K+/Na+ ratio, superoxide dismutase, peroxidase, catalase, ascorbate peroxidase activity, and the comprehensive score. The results show that SA improves the salt tolerance capacity of S. officinalis by modulating its photosynthetic rate, osmoprotectants, antioxidant levels, and ion homeostasis. However, the effectiveness of SA was not linearly related to its concentration. In summary, our findings reveal the protective roles of SA against salinity in S. officinalis and suggest that the use of 0.6 mmol L−1 of SA in salt stress conditions could be an effective approach to reduce the damage caused by saline soil in S. officinalis.

Land use affects ecosystem stability and agricultural ecological security in black soil regions. Additional attention is required regarding the impact of different land-use patterns on black soil. However, the construction of sustainable agricultural ecological security in black soil environments is a dynamic process that depends on the reviews of experts and statistical analyses of literature data. This study quantitatively reviewed the past 20 years of the literature regarding black soil. Using the superposition of the expert knowledge map and machine clustering, knowledge regarding land use in black soil fields was classified structurally. Further, studies directly related to the spatiotemporal pattern of land use were identified, and frequently cited works of the literature were screened to build a dynamic knowledge network of black soil research. The results show that (1) the cooperative relationship among China, the United States, and Canada is the strongest, but the density of cooperation networks between other countries is low; (2) land-use research regarding black soil is divided into four research areas: soil microbial community and activity, soil erosion and ecological processes, ecological management of land use, soil organic matter, and element cycling; (3) the monitoring and management mode of land use in black soil areas should be established to include information management that incorporates knowledge of the cultivated land factor potential, grain production capacity assessment, soil erosion evaluation and prediction, and farmland landscape planning.