Detection of Mycoflora and Aflatoxin B1 in the Seeds of Inodorous Melons (Cucumis melo L.)

Abstract

Twenty-two seed samples of inodorous melons, collected from the areas of Peshawar, Swabi, Tordher, Fatu-chuk, Mardan, Karachi, Islamabad, Ghotki, and Mandibahauddin, yielded 75 species of 36 fungal genera, isolated through ISTA (International Seed Testing Association) techniques. The agar plate method was chosen as being best for the qualitative and quantitative isolation of fungi, followed by the standard blotter method. The agar plate method yielded 64 species of 29 genera, while the blotter method yielded 24 species belonging to 14 genera. The deep-freezing method yielded only 2 species belonging to 2 genera. Aspergillus niger , followed by A. flavus , Chaetomium globosum , and Rhizopus stolonifer were the most dominant fungi in all 3 methods used. Forty species belonging to 25 genera had not been previously reported from Pakistan. Seven seed samples, which were highly infected with fungi, were grown in test tube slants, included samples from Tordher (1), Ghotki (1), Mandibahauddin (1), Karachi (2), Islamabad (1), and Fatu-chuk (1). Aspergillus flavus was the most dominant fungi, causing pre-emergence rot of seedlings. Fusarium oxysporum caused 3.6 % of seedling deaths after 10 - 12 days of incubation. Seed samples from Islamabad, Mandibahauddin, and Swabi were highly infected with A. flavus . The level of aflatoxin B 1 estimated through CD-ELISA for the 3 samples was 32.64 ppb (Swabi), 11.48 ppb (Islamabad), and 7.30 ppb (Mandibahauddin), respectively, of which the seed sample from Swabi contained the highest level of aflatoxins. Surface sterilization of seeds with 1 % Calcium hypochlorite (Ca (OCl) 2 )greatlyreduced the incidence of both saprophytic and superficial pathogenic fungi. doi: 10.14456/WJST.2016.3