Effects of different surface sterilization protocols on fungal load and germination of black henbane seeds

Black henbane (Hyoscyamus niger L.) is an important medicinal plant rich in tropane alkaloids with significant pharmacological effects. To extract these valuable metabolites, seeds are mostly used as the initial material in tissue culture techniques. Due to the intricate surface structure of the seeds, coupled with cultivation of the plant under unsuitable ecological conditions, a high risk of contamination during in vitro culture arises. As such, it is important to determine the most suitable sterilization method for successful germination of black henbane seeds under in vitro conditions. In this study, the effects of 10 different sterilization protocols with ethyl alcohol (EtOH), sodium hypochlorite (NaOCl), copper sulfate (CuSO4), hydrogen peroxide (H2O2), mercury chloride (HgCl2), and silver nitrate (AgNO3), on reduction of the fungal contamination of black henbane seeds was determined by the agar test method. Additionally, the germination rates, as well as shoot lengths and fresh plant weights of the germinated seedlings, were investigated. As a result, it was found that Alternaria, Fusarium, and Penicillium species were the most common fungi on black henbane seeds. Among the chemicals used in the sterilization protocols, AgNO3 was found as the most effective one, completely inhibiting fungal growth. Sterilization protocols with AgNO3 also yielded the highest germination rates.