Salt stress is a major abiotic factor limiting grapevine growth and yield. To elucidate the physiological and molecular regulatory mechanisms underlying salt tolerance in grapevine, this study used ‘Carménère’ (Vitis vinifera) and ‘Pinot Noir’ (Vitis vinifera) as experimental materials. Under 200 mmol/L NaCl stress, the physiological response characteristics of the two cultivars were systematically compared, and transcriptome sequencing combined with qRT-PCR analysis was conducted to explore the molecular basis of their differences in salt tolerance. The results showed that salt stress significantly impaired photosynthetic performance and disrupted cellular homeostasis in grapevine; however, the reductions in relative chlorophyll content (SPAD value), maximum photochemical efficiency of photosystem II (Fv/Fm), and photosynthetic performance were significantly smaller in ‘Carménère’ than in ‘Pinot Noir’, indicating greater stability of the photosynthetic apparatus in ‘Carménère’. Meanwhile, ‘Carménère’ maintained higher activities of antioxidant enzymes and higher levels of non-enzymatic antioxidants, effectively reducing reactive oxygen species accumulation and membrane lipid peroxidation. In addition, under salt stress, ‘Carménère’ accumulated greater amounts of osmotic adjustment substances and maintained lower Na⁺ content and higher K⁺ content, demonstrating a more efficient capacity for osmotic regulation and ion homeostasis. Transcriptomic analysis revealed that the plant hormone signal transduction, MAPK signaling, and glutathione metabolism pathways were significantly enriched in ‘Carménère’, with multiple key genes being coordinately upregulated under salt stress. Taken together, these findings indicate that ‘Carménère’ achieves enhanced salt tolerance through a multilayered signaling regulatory network that coordinates physiological defense responses. This study provides a theoretical basis for elucidating the mechanisms of salt tolerance in grapevine and for the molecular breeding of salt-tolerant cultivars.

Microbial inoculants, as a new type of product that combines economic efficiency with ecological sustainability, play an important role in promoting plant growth and development, increasing crop yields, and enhancing plant resistance to abiotic stress. This study used the wine grape cultivar (Vitis vinifera ‘Pinot Noir’) as experimental material to systematically investigate the effects of microbial inoculants on the soil–leaf–fruit system during the late growth stage of grapes under salt stress conditions (200 mM NaCl). This study analyzed the regulatory effects of microbial inoculants on soil physicochemical properties, leaf physiological and biochemical characteristics, as well as fruit yield and quality. The results showed that salt stress significantly inhibited the growth of Pinot Noir grapes. However, the application of microbial inoculants effectively alleviated the negative effects of salt stress. By enhancing the plant’s antioxidant defense capacity and regulating physiological metabolic pathways such as osmotic balance, the inoculants significantly mitigated the inhibitory effect of salt stress on fruit development. Notably, the S+JH treatment group demonstrated particularly outstanding results, with hundred-berry weight, single-bunch weight, and yield per plant increasing significantly by 15.96%, 12.47%, and 28.93%, respectively, compared to the salt stress group (S). Additionally, this treatment also stabilized free amino acid content and suppressed excessive organic acid synthesis. This study provides new technical insights into the application of microbial inoculants for saline-alkali land improvement and stress-resistant cultivation of horticultural crops such as grapes, holding significant practical value for promoting the sustainable development of the grape industry in saline-alkali regions.

Grape is a major economic crop in northwestern China, playing a vital role in the region’s agricultural economy. However, in recent years, soil salinization has intensified due to global warming and improper irrigation practices, resulting in significant declines in grape yield and quality. Addressing the adverse effects of salt stress on grape growth is of critical importance. Therefore, this study explored the effects of the exogenous application of microbial fertilizer Bacillus velezensis GB03 on the photosynthesis of Pinot Noir grapes under salt stress. Using Pinot Noir plants under normal growth conditions as the control group, salt stress was simulated by applying 200 mM NaCl. The microbial fertilizer GB03 was first diluted with water and then applied exogenously at three concentrations: low (300-fold dilution), medium (200-fold dilution), and high (100-fold dilution). The study measured the effects of these treatments on photosynthetic gas exchange parameters, chlorophyll fluorescence parameters, relative chlorophyll content, and single-plant yield under salt stress. The results demonstrated that salt stress significantly reduced photosynthesis in grape leaves, whereas the application of microbial fertilizer notably enhanced photosynthetic efficiency and fruit yield. Among the treatments, the medium-concentration fertilizer group exhibited the most pronounced improvements in net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), and single-plant yield (SPY). Furthermore, chlorophyll fluorescence parameters and relative chlorophyll content in this group were significantly higher than those in the other treatment groups. Principal component analysis confirmed that the medium-concentration treatment had the highest photosynthetic capacity, suggesting that it effectively alleviated salt stress by enhancing photosynthetic performance, thereby increasing fruit yield. This study provides a scientific foundation for the use of microbial fertilizers to mitigate soil salinization and improve salt tolerance in grape cultivation. The findings have significant implications for enhancing grape yield and quality under saline conditions.