Study on growth inhibition of Aspergillus flavus and aflatoxin B1 reduction in Pistachio by Trichoderma strains

In this investigation the effect of Trichoderma isolates in inhibition of Aspergillus flavus growth and reducing of aflatoxin B1 (AFB1) was studied in culture media and pistachio nuts. Among Trichoderma isolates, T1, T3, T4 and T17 isolates showed significant impact on inhibiting of A. flavus R5growth. T3 and T4 isolates were the most effective isolates, which caused 84.40% and 77.88% reduction of aflatoxin produced by A. flavus R5on pistachio and 88.03% and 79.73% reduction of aflatoxin B1 which was added to the medium respectively. In order to study the way the Trichoderma isolates affected the pathogen, the influence of volatile compounds and filtrate culture extract of Trichoderma isolates on A. flavus R5 growth were investigated. Study on volatile compounds effect showed that T1, T3, T4 and T17 isolates with 60.66%, 68.88%, 63.33% and 59% reduction of fungal growth, respectively. The results showed that T1, T3, T4 and T17 isolates could inhibit the mycelia growth of A. flavus in PDB liquid medium. Isolates of T3 and T4 caused 58.88% and 50.01% reduction of fungal biomass, followed by 90.76% and 86.25% reduction of aflatoxin B1 (AFB1), respectively. Results of the most experiments that was done in this study showed that T3 and T4 isolates are the most effective isolates in biological control of A. flavus R5. According to ITS1- 5.8s- ITS2 Gene Sequence analysis, T1, T3 and T4 isolates belonged to T. harzianum, T. longibrachiatum and T. harzianum, respectively.