Occurrence of aflatoxin in peanut under field conditions
1997
Arunsri Wongurai (Department of Agriculture, Bangkok (Thailand). Plant Pathology and Microbiology Div. Seed and Post-harvest Pathology Research Group)
In 1992-94 in order to investigate factors affecting invasion of A. flavus and aflatoxin production. The first factor was drought period prior to harvest, the second factor was effects of damaged pods, and the third factor was effect of plant maturity. Effects of drought periods on A. flavus population and aflatoxin production were investigated in dry and rainy season in 1992. There were 5 drought periods; 0, 20, 30, 40 and 50 days prior to harvest. The treatments were arranged in randomized complete block with 4 replications. Population of A. flavus in soil were determined throughout the growing season. The mature sound pods were decreased significantly with drought periods. Meanwhile the percentage of damaged pods caused by A. flavus was not different among the five periods of drought. Aflatoxin contamination was found only in the samples taking from the treatments which drought occurred at 20 and 30 days prior to harvest. In addition the soil of drought treatments had higher temperature (35-37 deg C) than irrigated treatment (27-30 deg C) The second factor to investigate was effects of damaged pod on the occurrence of A. flavus population and aflatoxin contamination. Eighteen samples of peanut pods collected from farmers' fields were examined. 16 percent of damaged pods contained 21-1255 micro g/kg of Aflatoxin but in the good mature sound pods no any toxin was detected. The third factor to investigate was the effects of maturity of the plant on aflatoxin contamination. Peanut pods at the age of 85, 95, 105, 110 and 120 days were analyzed for aflatoxin contamination. Aflatoxin was detected in the pods older than 105 days.
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