Studies on relationship of kernels 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 ears at 87,94,101,108,115 and 134 days after planting. Each sample consisted of ten ears, 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 kernal infection were determined whereas aflatoxin was analysed. The result revealed that 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 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 1-1.5 %. Percentage of the fungi-infected kernels increased 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 less A. flavus. However, more fungi were found on kernels from 134 day old plants. In all 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 plants. Later, concentration of aflatoxin in kernels collected from all parts of the ear and all varieties of 134 day old plants increased to 5 ppb.