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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Corn Host Plant Resistance Research » Research » Publications at this Location » Publication #205797
Title: Occurrence of aflatoxin in three maize genotypes over five years in northern Mississippi

Author
item Hawkins, Leigh
item Windham, Gary
item Williams, William

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2007
Publication Date: 4/1/2008
Citation: Hawkins, L.K., Windham, G.L., Williams, W.P. 2008. Occurrence of aflatoxin in three maize (Zea mays L.) hybrids over 5 years in Northern Mississippi. Mycopathologia. 165:165-171.

Interpretive Summary: Aflatoxin is produced by the fungus Aspergillus flavus. Aflatoxin levels vary with environmental conditions, genotype and location. The objectives of this research are (1) to evaluate aflatoxin accumulation in three corn genotypes (Pioneer Brand 3223, Mo18W×Mp313E and Mp313E×Mp420) from 1998 to 2002 treated with A. flavus; and (2) to evaluate favorable weather conditions for aflatoxin contamination. Environmental data were collected for several time periods spanning the growing seasons. For each, six factors were studied: (1) growing degree units, (2) rainfall, (3) the number of days the maximum temperature exceeded 30°C (4) the number of days the minimum temperature exceeded 22°C; (5) pan evaporation; and (6) the number of days that both the average temperature exceeded 25°C and the maximum temperature exceeded 35°C. Years 1998 and 2000 represented the highest aflatoxin levels (1186 and 901 ng•g-1; p < 0.0001); while 1999 (39 ng•g-1) represented the lowest. Pioneer 3223 had significantly higher levels of aflatoxin (1198 ng•g-1) than Mp313E×Mp420 (205 ng•g-1) and Mo18W×Mp313E (161 ng•g-1; p < 0.0001). Of the weather-variables generated, 32 were significantly correlated with aflatoxin accumulation in Pioneer 3223; 29 in Mo18W×Mp313E and 7 in Mp313E×Mp420. The hybrids had in common six variables with significant correlations to aflatoxin accumulation. Four of these occurred during the time period from 65 to 85 days after planting. These results suggest that regardless of the hybrid’s maturity or physiological development, the time from 65 - 85 days after planting may be indicative of a period of stress which leads to greater aflatoxin accumulation at harvest.

Technical Abstract: Aflatoxins are produced as secondary metabolites under conducive climatic conditions by Aspergillus flavus. The incidence of aflatoxin varies with environmental conditions, genotype and location. The objectives are to evaluate three maize genotypes (Pioneer Brand 3223, Mo18W×Mp313E and Mp313E×Mp420) from 1998 to 2002 in response to A. flavus inoculation and aflatoxin contamination; and to evaluate favorable weather conditions for aflatoxin contamination. Environmental data were collected for time periods spanning the growing seasons. For each, six factors were studied: growing degree units, rainfall; number of days the maximum temperature exceeded 30°C; number of days the minimum temperature exceeded 22°C; pan evaporation; and number of days the average temperature exceeded 25°C and the maximum temperature exceeded 35°C. Years 1998 and 2000 represented the highest aflatoxin levels (1186 and 901 ng•g-1; p < 0.0001); while 1999 (39 ng•g-1) represented the lowest. Pioneer 3223 had significantly higher levels of aflatoxin (1198 ng•g-1) than Mp313E×Mp420 (205 ng•g-1) and Mo18W×Mp313E (161 ng•g-1; p < 0.0001). Of the weather-variables generated, 32 were significantly correlated with aflatoxin accumulation in Pioneer 3223; 29 in Mo18W×Mp313E and 7 in Mp313E×Mp420. The hybrids had in common six variables with significant positive correlations to aflatoxin accumulation. Four of these occurred during the 65 to 85 days after planting and were all temperature related. These results suggest that regardless of the hybrid’s maturity or physiological development, the time from 65 - 85 days after planting may be indicative of a period of stress which leads to greater aflatoxin accumulation at harvest.