Physiological and Enzymatic Antioxidant Responses of Several Local <i>Pyrus communis</i> L. cv on Different Rootstocks under NaCl Stress

Salt stress poses a substantial threat to fruit cultivation in arid and semi-arid regions. An essential aspect of mitigating this challenge involves understanding the adaptive changes in plants under salinity conditions. In this study, salinity stress (0, 20, 40, and 80 mM) induced in Ankara and Deveci pear varieties grafted onto OHxF 97, OHxF 333, and BA 29 rootstocks. Plant height and diameter, stomatal conductance, photosynthetic pigments and K+/Na+ ratio exhibited a decreasing trend, indicating the impact of salt stress. Conversely, the salt stress index and the activities of antioxidant enzymes including superoxide dismutase, catalase, and ascorbate peroxidase showed an increasing trend, highlighting the plant's defense mechanisms against oxidative stress. In our comprehensive evaluation, the Deveci x OHxF 97 demonstrated a higher level of tolerance to sodium chloride stress compared to other combinations. Notably, combinations involving the BA 29, particularly Ankara x BA 29, exhibited more pronounced damage under NaCl stress. An intriguing finding was the announced response of enzymatic antioxidants, where despite a higher increase in SOD activity in the Deveci x OHxF 97, CAT and APX activities were generally higher in the Ankara x BA 29. This suggests the effective operation of enzymatic antioxidants in ameliorating oxidative damage in cells exposed to NaCl stress, irrespective of the overall stress tolerance of the plant, within the Pyrus. This study contributes valuable insights into the complex interplay between pear varieties, rootstocks, and NaCl stress, providing a foundation for informed decision-making in orchard management practices to enhance the resilience of pear cultivation in challenging environmental conditions.