Abstract:

Peanut and its products are generally susceptible to Aspergillus flavus and contaminated consequently aflatoxin under both preharvest and postharvest conditions. In China, both preharvest infection because of end-of-season drought and postharvest infection because of humid and high temperature environment and poor storage condition were severe. Utilization of genetic resistance is one of the most efficient approaches for the control of aflatoxin. Durability of resistance to Aspergillus flavus infection in storage is one of important resistant components in peanut. Up to now, several genotypes with aflatoxin resistance have been identified but not been efficiently used in breeding program because of poor agronomic and chemical characters. In the present study, peanut genotypes with diverse reaction to infection of Aspergillus flavus were used to investigate the persistence of resistance in seed storage and the impact of intact testa on aflatoxin contamination. The results indicated that the resistance to Aspergillus flavus could be lasted for at least seven months in resistant germplasms under conventional storage conditions in central China after harvest. No significant difference between the seed samples stored for seven months and freshly harvested one in terms of invasion ratio and infection index. However, the resistance could be declined or lost after nine-month storage. The quick decline of the resistance was due to the change of temperature. The impact of intact testa on aflatoxin production under artificial inoculation was different between the resistant and susceptible genotypes. The aflatoxin content in samples with intact testa was lower in resistant genotypes but higher in susceptible genotypes than that with damaged testa. Peanut genotypes with high oil, protein and oleic acid were generally more susceptible to Aspergillus flavus invasion. The infection by Aspergillus flavus was significantly negative correlated with oleic acid content and significantly positive correlated with linolenic acid content. And the aflatoxin contamination content by Aspergillus flavus are significantly negative correlated with oleic acid content. Two genotypes with resistance and good seed quality, G845 and G8 had been identified.

Key words: Aspergillus flavus, Durability of resistant, Testa, Aflatoxin production