RELATION OF AFLATOXINS IN COTTON SEEDS AT HARVEST TO FLUORESCENCE IN FIBER

In bulk samples of U. S. cotton seed collected to represent all harvestable bolls, aflatoxins were found infrequently and, when present, at very low levels. However, seeds from occasional individual bolls whose fiber exhibited an Aspergillus flavus—associated greenish yellow fluorescence contained variable but generally high levels of aflatoxin Bi. Seeds from visibly rotted bolls lacking the fluorescence also sometimes contained aflatoxin Bi but at a much lower average level. In laboratory culture, 49 out of 50 isolates of A. flavus produced aflatoxin Bi, the amount being unrelated to the geographical origin of the culture, while other seed-invading field fungi produced little or no aflatoxins. All A. flavus isolates caused the greenish yellow fluorescence in living cotton fiber, whereas no other field fungi tested did so. The fiber fluorescence, therefore, appears to offer promise as a preliminary screening test to locate seeds containing high levels of aflatoxins at harvest. Penetration of A. flavus occurred through the chalazal end of the seed. © 1969, American Chemical Society. All rights reserved.