Physiological and Biochemical Responses of Moroccan Grapevine (Vitis vinifera L.) Varieties to Salinity Stress: Implications for Environmental Stress Adaptation

Abstract

Salinity is a major environmental constraint limiting grapevine growth, productivity, and long-term sustainability, particularly in arid and semi-arid regions. Understanding the mechanisms underlying varietal tolerance is therefore essential for improving vineyard resilience. This study evaluated four Moroccan grapevine varieties (Bezoul Awda, Sbiea Bnat, Zbarjel, and Krichi) subjected to increasing NaCl concentrations, using morphological, physiological, biochemical, and enzymatic indicators. Salinity significantly reduced shoot and root growth, biomass accumulation, photosynthetic pigments, and relative water content across all cultivars. Conversely, stress-related metabolites such as proline, malondialdehyde, and hydrogen peroxide increased markedly, reflecting enhanced oxidative pressure. Antioxidant enzymes (catalase, peroxidase, and polyphenol oxidase) exhibited strong activation, suggesting the triggering of defense pathways to mitigate cellular damage. Correlation analysis revealed positive associations among growth and morpho-physiological traits, and negative correlations between these traits and stress indicators. Conversely, antioxidant activities were positively correlated with salinity intensity. Principal component analysis showed that Bezoul Awda and Krichi displayed better growth maintenance and water balance under stress, indicating stronger tolerance strategies compared with Sbiea Bnat and Zbarjel, which exhibited higher biochemical stress responses. Hierarchical clustering grouped SB and KC as tolerant cultivars, whereas ZL and BA formed a more sensitive group. Overall, the integration of morpho-physiological and biochemical markers proved effective in differentiating tolerance mechanisms and identifying grapevine genotypes adapted to saline environments.