Effect of Irrigation Regimes on Aflatoxin Contamination of Peanut Pods1

Abstract

Abstract Florunner and Florigiant peanuts were grown and foliar inoculated with an aflatoxin producing isolate of Aspergillus parasiticus (NRRL 2999) 30 days after planting. Four replicates were grown in plots under rainfall controlled shelters with six irrigation treatments: (1) wet from day 0-145, (2) dry from days 36-70, (3) dry from days 71-105, (4) dry from days 106-145, (5) dry from days 36-105, (6) dry from days 71-145. Aflatoxin concentrations from Florunner peanuts were significantly different between treatments (P = 0.01) in 1974 and 1976 but not in 1975 or 1977. In 1974 and 1976, sound mature kernels of Florunner from treatments 4 and 6 contained significantly more aflatoxin when compared to other treatments. Aflatoxin contamination of Florigiant sound mature kernels from treatments 4 and 6 in 1975 and treatment 6 in 1974 was significantly greater (P = 0.01) than other treatments, but not in 1977. No data were taken in 1976 for Florigiant peanuts. Water stress during the last 40 to 75 days of the season contributed to aflatoxin contamination of sound mature kernels three of the four years on one or both cultivars. Because of year to year variation, drought stress alone does not consistently affect field aflatoxin contamination. In some years other environmental factors must have interacted with drought stress to promote or inhibit preharvest aflatoxin contamination. However, in all treatments where irrigation was applied during the last 40 days of the season, no significant aflatoxin contamination was detected in any cultivar any year of the test.