Studies on relationship of kernel moisture content, percentage of fungi and Aflatoxin concentration on preharvest maize kernels

Seven varieties of maize including KS4, KS5, KS6, SW1, SW2, KSX 2301 and KTX 2602 were grown at the National Corn and Sorghum Research Center on July 20, 1987. Maize kernels were randomly collected from the ear at 87, 94, 101, 108, 115 and 134 days after planting. Each sample consisted of ten ears, then kernels from each ear were collected separately from the base, middle and tip of the ear. Moisture content (MC) of kernels was measured, the kind of fungi and percentage of kernel infection were determined whereas aflatoxin was also analysed. Kernels collected from all varieties and all parts of the ear at 87 days after planting had over 35 % MC. Moisture in kernels was gradually decreased down to 25 % MC at 115 days after planting. Average values of all fungi found on kernels of all varieties collected at 87 days of the planting were 1 to 2 % and A. flavus of 1-15 %. Percentage of the fungi-infected kernels increased up to 15 when kernels collected at 101 days after planting. Among those fungi observed, Penicillium species (20 %) were predominant while A. flavus was at 3.5 %. Maize collected from 115 day-old-plants possessed less fungi and A. flavus as well. However, more fungi were found on kernels from 134 day-old-plants. Of all maize varieties, average of detected fungi on kernels collected from the base, middle and tip of the ears were 6.78, 4.76 and 5.11 whereas average percentage of A. flavus were 2.7, 1.96 and 1.79, respectively. Aflatoxin was not detected from kernels obtained from all parts of the ear and all varieties of 87 day-old-plants. However, less than 1 ppb of aflatoxin was found from 115 day-old-plant. Later, concentration of aflatoxin in kernels collected from all parts of ear and all varieties of 134 day-old-plants increased up to 5 ppb.