Role of enzymatic antioxidants on salinity tolerance of some rootstocks used in European pear<i> (Pyrus</i><i> communis</i> L.) cultivation

Aim of study: Plants, whether halophytes or glycophytes, develop defensive strategies to mitigate the damage caused by salt stress. This study aimed to investigate the biochemical responses of selected pear rootstocks under sodium chloride (NaCl) stress. Area of study: Fruit Research Institute, E & gbreve;irdir, Isparta, T & uuml;rkiye. Material and methods: One-year-old non-grafted rootstocks, pear OHxF 97, OHxF 333 (Old Home x Farmingdale) and Fox 11, and quince BA 29 were used. Four NaCl concentrations were applied: 0 mM (control), 20 mM, 40 mM, and 80 mM. Main results: Relative water content (RWC%), stomatal conductance (gs), and hydrogen peroxide (H2O2) levels in leaves significantly decreased with increasing NaCl stress across all rootstocks. Antioxidant enzyme activities and sodium (Na+) content generally increased in response to higher stress levels. Based on RWC%, gs, and Na+ values, Fox 11 and BA 29 were the most negatively affected. In OHxF 97, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), dehydroascorbate reductase (DHAR), ascorbate peroxidase (APX), and glutathione reductase (GR) significantly increased under NaCl stress. Research highlights: Enzymatic antioxidant defense mechanisms play a key role in salinity tolerance in European pear. OHxF rootstocks, particularly OHxF 97, are recommended for soils with salinity levels close to the threshold of 4 dS m-1.