Effects of different putrescine doses on physiological activites in strawberry plant exposed to salt stress

Salinity problems may occur in most of the irrigable agricultural lands. Today, the increasing saline areas seriously threaten the sustainability of agricultural production. In this study, the effects of different doses of putrescine (100 ppm, 150 ppm, and 200 ppm) on growth parameters, antioxidant activity, and leaf and root nutrient contents in the Albion strawberry cultivar grown using ½ strength Hoagland nutrient medium in liquid culture under salt stress (1000 mg/l NaCl) was determined. According to the results, salt stress caused a decrease in DPPH scavenging activity, total protein, total anthocyanin, total soluble carbohydrate, and total phenolic substance contents, as well as negatively affecting root and leaf weight, root number and length, and chlorophyll content. It was observed that salt stress increased the enzyme activities of catalase (CAT), hydrogen peroxide (H2O2), and lipid peroxidation (MDA) in the leaves of strawberry plants, and decreased the activities of ascorbate peroxidase (APX), proline and superoxide dismutase (SOD). In addition, while the sodium (Na) and magnesium (Mg) content increased, the copper (Cu) content decreased in the roots and leaves of the plants under stress. While the effects of putrescine doses on plant growth parameters in strawberries grown under salt stress conditions were not statistically significant, they increased the total phenolic content from 53,36 mg/g to 95,37 mg/g (100 ppm putrescine) in the salt application alone. A similar situation occurred in the total amount of anthocyanins, which increased from 0,74 mg/g (salt) to 1,78 mg/g (200 ppm) with putrescine administration. In antioxidant activity, a 150 ppm dose of putrescine is the best result. Antioxidative enzymes APX, proline, and SOD activities increased more than twofold with putrescine doses applied to strawberries under salt stress. CAT was not statistically different. It was determined that the oxidative enzymes H2O2 and MDA activities decreased significantly with putrescine applications. The study results show that putrescine has positive effects by regulating enzymatic activity in strawberry plants under salt stress.