Seed Tolerance in Peanuts (Arachis hypogaea L.) to Members of the Aspergillus flavus Group of Fungi1

Abstract

Abstract An assay of cured, hand-shelled seeds of various peanut genotypes for tolerance to members of the Aspergillus flavus group of fungi has been performed in Florida for the years 1971–1974. The assay involved exposing peanut seed at 20–30% moisture to conidia of A. parasiticus or A. flavus in petri plates and incubating at 25 C. After 1 week, the percentage of the seeds with sporulating colonies of the test fungus was determined. Typically, individual lines or cultivars were evaluated on the basis of the average of three plates. However, second or third assays of the same seed lots were done on 45 occasions during the 4 year period. More than 95% of these repeated assays yielded data similar to those from the original assay. However, different seed lots of the same line also were assayed and did not always yield similar results unless the dates of digging, methods of curing and location of the plantings were the same. Some shifts in susceptibility were quite extreme. One lot of stackpole cured ‘Altika’ resulted in 12% colonized seeds in the assay but 77% of a windrow-cured seed lot, dug on the same day from the same plot had colonies of the test fungi. No particular change in the harvesting procedure was consistently associated with increases or decreases in apparent susceptibility. Based on tests of all seed lots of 15 commonly grown cultivars during the years 1971–1974. ‘Florunner’ was the most tolerant cultivar and ‘Tifspan’ was the most susceptible.