Improvement of Seedling Growth in Cucumber Through External Putrescine Treatments Under Salt Stress

The objective of this research was to investigate the impact of external putrescine (Put) treatments at varying concentrations on the seedling growth of cucumber (Cucumis sativus L.) under saline conditions. A total of eight different treatments, including 200 mM NaCl and three different putrescine doses (0.4, 0.8, and 1.2 mM), were used to evaluate their individual and combined impacts. The results indicated that salt stress led to a significant reduction in multiple morphological and physiological traits, such as seedling height, fresh and dry weight of seedlings, stem diameter, number of leaves, chlorophyll content, dry matter ratio, and color quality. However, especially the 0.4 mM Put treatment significantly mitigated the adverse effects of salinity and improved seedling growth under both normal and saline conditions. The highest values for most growth and physiological parameters were observed with 0.4 mM Put treatment. On the other hand, higher putrescine concentrations, particularly in combination with salt stress, did not provide additional benefits and generally reflected the negative effects of salinity alone. It was found that 0.4 Put + 200 NaCl treatment increased seedling height by 10.68%, stem diameter by 25.23%, seedling fresh weight by 41.94%, number of leaves by 26.32%, chlorophyll content by 46.51% and dry matter ratio by 24.97% compared to 200 NaCl treatment. It was concluded that the 0.4 mM Put treatment could be recommended to enhance seedling growth in cucumber under saline conditions. These findings suggest that external putrescine application at optimum doses can serve as a practical strategy to improve seedling growth and salt stress resistance in cucumber cultivation.