Retardation of the Elaboration of Aflatoxin in Cottonseed by Impermeability of the Seedcoats1

Impermeable cottonseed were compared with permeable seed to determine their value in resisting the elaboration of aflatoxin. Undelintered seed were inoculated with a toxigenic strain of Aspergillus flavus and stored for periods up to 49 days under conditions of moisture and temperature conducive to fungal growth and to production of aflatoxin. When stored for 21 days under these conditions, in all cases except one, “selected‐impermeable” seed of 1964 and 1966 experimental crops developed less than 0.2 mg aflatoxin/kg. Permeable seeds (commercial and experimental) treated under the same conditions for the same time contained from 78 to more than 500 mg aflatoxin/kg. The toxigenic fungus grew on or in fewer of the selected‐impermeable than the permeable seed. However, the available lots of impermeable seed which had been grown in 1965 contained a higher percentage of permeable seed than did the lots from other years because of poor storage. As much as 22 to 200 mg aflatoxin/kg were produced in 21 days even in selected‐impermeable seed obtained from improperly stored lots grown in 1965. Apparently cottonseed stored under different moisture conditions differed in their degree of impermeability and susceptibility to the action of A. flavus. When impermeability was maintained, the seed were protected from significant development of aflatoxin.