Tolerance of maize varieties to infection by aspergillus flavus and aflatoxin accumulation

Abstract

Recurrent outbreaks of aflatoxin poisoning in Kenya pose a major food safety concern considering that maize is the main staple food in the country. A study was conducted in Mwea and Waruhiu over two growing seasons to evaluate the susceptibility of 16 maize varieties to Aspergillus jlavus and aflatoxin accumulation. The varieties tested were H513, Duma 43, DK8031, DH01, DH02, DH04, Panner 77, Panner 7-19M, Panner 4M, Panner 67/5243, H515, H516, KCB, H614, Pioneer 3253 and Katumani composite. Cobs were inoculated with A. jlavus in the field by silk channel inoculation method. Aspergillus rot assessment was done at physiological maturity. At maturity cobs were harvested, dried to 13% moisture content. Sub-samples (500 g) were adjusted to 10, 13.5, 15, 17 and 20%. Percent kernels infection with Aspergillus jlavus was determined by plating kernels on agar medium while aflatoxin content was determined by enzyme linked immunosorbent assay (ELISA). The varieties differed in visual Aspergillus rot rating with varieties Katumani and Katumani composite B having the lowest rating while H614 had the highest Aspergillus infection. Husk coverage also influenced the aflatoxin contamination with variety P77M, which had a loose coverage having a higher aflatoxin concentration. Aspergillus jlavus kernel infection was significantly affected by sampling time, moisture content and variety. Samples stored at 17% moisture content had significantly higher A. jlavus kernel infection. Most varieties were susceptible to Aspergillus jlavus infection and had aflatoxin levels greater than luug kg"I aflatoxin BI allowed in Kenya. The study demonstrated the need for development of varieties that are resistant to Aspergillus ear rot as an option for managing aflatoxin poisoning.