Salt stress can adversely affect global agricultural productivity, necessitating innovative strategies to mitigate its adverse effects on plant growth and yield. This study investigated the effects of exogenous salicylic acid (SA), grafting (G), and their combined application (GSA) on various parameters in tomato plants subjected to salt stress. The analysis focused on growth characteristics, photosynthesis, osmotic stress substances, antioxidant enzyme activity, plant hormones, ion content, and transcriptome profiles. Salt stress severely inhibits the growth of tomato seedlings. However, SA, G, and GSA improved the plant height by 22.5%, 26.5%, and 40.2%; the stem diameter by 11.0%, 26.0%, and 23.7%; the shoot fresh weight by 76.3%, 113.2%, and 247.4%; the root fresh weight by 150.9%, 238.6%, and 286.0%; the shoot dry weight by 53.5%, 65.1%, and 162.8%; the root dry weight by 150.0%, 150.0%, and 166.7%, and photosynthesis by 4.0%, 16.3%, and 32.7%, with GSA presenting the most pronounced positive effect. Regarding the osmotic stress substances, the proline content increased significantly by more than 259.2% in all treatments, with the highest levels in GSA. Under salt stress, the tomato seedlings accumulated high Na⁺ levels; the SA, G, and GSA treatments enhanced the K⁺ and Ca²⁺ absorption while reducing the Na⁺ and Al³⁺ levels, thereby alleviating the ion toxicity. The transcriptome analysis indicated that SA, G, and GSA influenced tomato growth under salt stress by regulating specific signaling pathways, including the phytohormone and MAPK pathways, which were characterized by increased endogenous SA and decreased ABA content. The combined application of grafting and exogenous SA could be a promising strategy for enhancing plant tolerance to salt stress, offering potential solutions for sustainable agriculture in saline environments.

Soilless cultivation is increasingly utilized in supplying essential nutrients for greenhouse crops. However, the impact of coir cultivation under varying electrical conductivity (EC) conditions on cucumber growth and fruit quality, particularly through the regulation of gene expression during the vegetative stage, remains uncertain. In this study, we performed metabolic measurements on cucumber in both vegetative and reproductive stages under three different EC conditions and found metabolic products such as some primary metabolites (cellulose, many uncharged amino acids) and some secondary metabolites (rutin, cucurbitacin B) accumulated the most under EC of 5 dS·m⁻¹. Next, we conducted transcriptome profiling in cucumber leaves, revealing that the function of genes significantly regulated by EC was associated with photosynthesis, many anabolic processes, and membrane transport. Finally, a set of genes contributed to metabolites related to the fruit quality of cucumber were identified by the Orthogonal Partial Least Squares (O2PLS) analysis, including genes involved in the biosynthesis of amino acids, polysaccharides, and many secondary metabolites. Taken together, these findings suggest that coir cultivation in greenhouses with moderate EC can induce a transcriptome-wide change in gene expression, thereby contributing to enhancing the abundance of metabolites associated with cucumber fruit quality.