Effect of Some Sterilization Conditions on Seed Germination of Milk Thistle (Silybum marianum) in vitro

Milk thistle (Silybum marianum) is a valuable medicinal herb that has long been used in traditional European medicine, renowned for its effects on supporting and protecting liver function.Currently, the plant is cultivated worldwide to meet the growing necessity for treating liver diseases and other health problems.Micropropagation methods are needed to meet the demand for high-quality seedlings.A critical stage in this process is seed sterilization, as it directly affects germination rates and contamination levels during cultivation.Chlorine gas, a strong disinfectant, is frequently used to control microbial contamination on seeds.This study aimed to determine the most effective sterilization method for Silybum marianum seeds by comparing commercial bleach (sodium hypochlorite) and chlorine gas at varying concentrations and exposure times.It was found that chlorine gas sterilization was significantly more effective than commercial bleach.Specifically, the treatment using 3% chlorine gas for 45 minutes achieved the highest efficiency, with a germination percentage of 42.43%, a contamination level of 15.45%, and a seedling length of 3.59 cm after 14 days of culture.However, prolonged exposure to chlorine gas had a detrimental effect on seed germination.Seeds treated with chlorine gas for 75 minutes had the lowest germination rate (21.94%).Meanwhile, seeds sterilized with bleach had a much lower germination percentage of approximately 20%.Although longer exposure times or higher bleach concentrations minimized contamination, they also significantly lowered germination rates.Seeds treated with 15% bleach for 8 minutes achieved a germination rate of only 7.23%.The seedlings grew well, with no significant differences in morphology when seeds were treated with bleach or chlorine gas.Overall, the study concluded that chlorine gas is a simple yet highly effective method for sterilizing milk thistle seeds.This technique can be widely applied to micropropagation procedures for Silybum marianum.