Effects of variety, cropping system and soil inoculation with Aspergillus flavus on aflatoxin levels during storage of maize

Abstract

The effects of soil inoculation with A. flavus, variety and cropping system on the level of aflatoxin in stored maize were investigated under crop storage conditions in Benin. The experiment was organized in a factorial scheme (two varieties x two cropping system x with or without A. flavus soil inoculation) with eight treatments carried out in a completely randomized block design with three replications. A. flavus incidence in the plots soil was assessed both before and after soil inoculation. The harvested maize was stored for four months and cobs were sampled in a monthly interval and analyzed for the determination of Fusarium spp. colonization, Penicillium spp. and A. flavus cfu levels, insect pests population size and aflatoxin content. Multi-factorial analysis of variance and linear regression analyses with dummy variables were used to compare treatments. The concentrations of aflatoxin B 1 and B 2 in the kernels tended to increase with time during storage. Variety and fungal inoculation were the main factors influencing the levels of aflatoxins in stored maize. The improved variety showed a higher number of A. flavus cfu and aflatoxin B 1 and B 2 levels as compared to the local variety. Intercropping with Vigna unguiculata decreased the aflatoxin concentration in the improved variety but not in the local variety. The local variety had higher levels of Penicillium spp. and lower levels of Fusarium spp. than the improved variety. The treatments had no effect on the populations of the most common storage insect pests, but their levels were positively correlated with aflatoxin content. Both the initial inoculum level and the variety effect on the water content of the kernels after harvest played a significant role in A. flavus infection.

Assessment of Aflatoxin and Fumonisin Contamination of Maize in Western Kenya

“…Among the home-grown maize samples, intercropped maize had lower aflatoxin contamination than maize that had been grown in monoculture. These findings are consistent with those of the recent survey in eastern Kenya (Mutiga et al 2014) but contrast with previous reports on the effect of intercropping on aflatoxin levels (Hell 1997;Tedihou et al 2012). Aflatoxin contamination is positively correlated with crop stress (Chen et al 2004).…”

Impact of companion cropping on incidence and severity of maize ear rots and mycotoxins in Western Kenya

“…Similar results have been obtained in Africa, where for instance, reports indicate 40% reduction of aflatoxin concentration through removal of moldy, damaged and broken grains in Benin (Fandohan et al, 2005). In addition, reports indicate 20% reduction of fumonisins in Tanzania, Kenya and South Africa as a result of sorting (Kimanya et al, 2009;van der Westhuizen et al, 2010;Mutiga et al, 2014). However, owing to the fact that 80 % of arable land (Wiggins, 2009) and 75% of total maize production (Nyoro et al, 1999) are from smallholders farmers, mycotoxin recycling and high exposure to consumers are preeminently promoted by alternative use of infected ears by fungal rot (Bigirwa et al, 2007;Mukanga et al, 2011).…”

“…Studies by Ajanga and Hillocks (2000) reported positive and high correlation between stemborers and incidence of ear rots in maize. Additionally, an interplay of other factors such as increase of organic matter (Alakonya et al, 2008), cover cropping (Tédihou et al, (2012), and intercropping (Vincelli, 1997;Flett and Ncube, 2015) have been reported to reduce ear rot incidence in maize. The push-pull cropping system effectively controls stemborers in maize (Khan et al, 2014;Midega et al, 2015a, b), improves soil organic matter content (Midega et al, 2005) and provides other soil improvement benefits.…”

Análise de trilha da contaminação por aflatoxinas em grãos de milho armazenados

“…Marín et al (1998b) descrevem que espécies de Fusarium são capazes de colonizar rapidamente grãos danificados, reduzir a fonte de nutrientes disponível a outros fungos, tais como Aspergillus flavus e interferir no potencial de produção de aflatoxinas. Tédihou et al (2012) verificaram correlação inversa da incidência de Penicillium sp. com a incidência de A. flavus (r = -0,34) e a ocorrência de aflatoxina B 1 (r = -0,21).…”

“…Em razão dos problemas causados pelas micotoxinas à cadeia alimentar, alguns trabalhos foram realizados para estudar as correlações entre estas e as variáveis ambientais, físico-químicas e da incidência de fungos em grãos de milho recém-colhidos ou armazenados (Ono et al, 2006;Almeida et al, 2009;Bento et al, 2012;Tédihou et al, 2012). As correlações simples quantificam o grau e o sentido da associação linear existente entre duas variáveis, porém, não garantem uma relação de causa e efeito entre o grupo de variáveis envolvidas em relação a uma variável dependente de maior importância (Lúcio et al, 2013).…”