Effect of culture filtrates of Alternaria alternata on seed germination and seedling growth of sesame

Abstract Sesame (Sesamum indicum L.) is a major oilseed crop in Pakistan, possessing high nutritional and pharmacological properties. Sesame is highly susceptible to pathogenic fungi such as Alternaria alternata. In the present study, metabolites extracted from culture filtrates of Alternaria alternata using hexane, chloroform, ethyl acetate, and petroleum ether solvents were evaluated for activity on seed germination and seedling health of sesame. Seeds treated with solvent-extracted metabolites from culture filtrates of A. alternata showed low germination as compared to control. Maximum reduction in germination was reported in seeds treated with petroleum ether culture filtrate followed by ethyl acetate, hexane, and chloroform. Shoot length and root length were also reduced in seeds treated with petroleum ether culture filtrate followed by ethyl acetate, hexane, and chloroform. Seedling treated with solvent-extracted metabolites from culture filtrates of A. alternata showed various symptoms including chlorosis, necrosis, discoloration, and wilting. From the present study, it is concluded that A. alternata contains certain metabolites which can reduce seed germination and are destructive for seedling stage of sesame. This is a baseline study to evaluate highly active metabolites which can be managed further to decrease sesame yield loss.