A series of previous studies demonstrated that natural occurrence
of aflatoxins in peanut samples at harvest was influenced by
favorable climatic conditions. They showed that aflatoxin production
in peanuts was higher in hot dry conditions during the late
growing season. Neither the high temperature alone nor the
drought stress alone caused aflatoxin contamination (Hill et al.,
1983). The mean geocarposphere temperature of high aflatoxin
contamination in peanuts growing under drought stress was
29.6e31.3 C (Cole et al., 1985). The mean, threshold, and geocarposphere
temperature required for aflatoxin development during
the late part of the peanut growth cycle were found between
25.7 C and 27 C (Williams & McDonald, 1983).
Klich concluded that the aflatoxigenic fungus is isolated from a
wide range of climatic zones, but is more frequently found between
latitudes 16 and35 in warm climate zones and is not common
above 45 latitudes (Klich, 2007). In the light of relatively cool
temperatures in Liaoning Province all year around (annual average
maximum temperature being about 30 C), the average aflatoxin
content in peanuts was lower than the maximum amount allowed
for foodstuffs in China and other countries and hardly affected by
climate conditions.