Aflatoxins are secondary metabolites produced by Aspergillus flavus, A. parasiticus, A. tamari, A. bombycis and A. nomius species. Relative humidity (RH) is one of the most important parameters influencing the development of aflatoxins in pistachio orchards by Aspergillus species. The type of irrigation system affects density and frequency of the Aspergillus species in the soil. In the current study, to evaluate fungus population density three irrigation treatments (flood, drip-surface, and subsurface irrigation) were applied. In order to investigate the population density of Aspergillus flavus in different irrigation systems, sampling was done from soil and kernels of Shahpasand cultivar at Damghan's Pistachio Research Station under various types of irrigation systems implementation. The samples were inoculated on AFPA medium using serial dilution method. The results indicated that the population density of A. flavus ranged various in pistachio kernels and soils between different types of irrigation system. Through subsurface irrigation, the population density of fungal colonies was significantly at the lowest level. The results showed that the use of modified adopted subsurface irrigation system had been effective in reducing soil surface moisture and led to decrease of population density in comparison with the conventional surface drip irrigation. تفاصيل المقالة

Population density of Aspergillus section Flavi in pistachio kernels of Iranian cultivars was studied in main pistachio growing areas of Iran during 2015 to 2017. In order to investigate the rate of contamination of pistachio cultivars to Aspergillus section Flavi and aflatoxins, 13 pistachio cultivars, including Akbari, Kaleh-ghouchi, Ovhadi, Ahmad-aghaee, Momtaz, Italian pistachio, Shahpasand, Pesteh-e-ghermes, Pesteh-e-garmeh, Ghazvini, Abbasali and Khanjari were selected from different parts of Semnan, Khorosan Razavi and Kerman provinces. A total of 125 samples of pistachio kernels were collected from different cultivars of pistachio trees in orchards. The samples were cultured on AFPA using serial dilution method. After 3 to 7 days, the plates were examined and isolates of Aspergillus section Flavi were identified and relative densities of them were recorded. The values ranged from 1.6×103 to 1.6×104 CFU/g in pistachio samples.The statistical analysis showed that the population density of Aspergillus section Flavi was varied with the type of cultivars. The results indicated that among tested cultivars, Akbari showed the least and Shahpasand the most population density of Aspergillus section Flavi among pistachio cultivars, respectively. The aflatoxins content of pistachio samples were extracted and analysed through Thin Layer Chromatography (TLC) and flurodensitometer. There were Significant differences among different cultivars in the contamination of pistachio kernels to Aspergillus section Flavi and aflatoxin. (α =5%). It was observed that Akbari had the least whereas Shahpasand had the greatest amount of aflatoxin production, respectively. تفاصيل المقالة

Samples were collected from different regions of two provinces, Markazi and Semnan, their contamination by Aspergillus flavus was examined. The results of A. flavus colony counts in different samples of almond showed that among 20 experimented samples, 11 samples were contaminated by fungus; therefore, 8 cultivars of almond, Shahroud 6, Shahroud 21, Shahroud 12, Shahroud 8, Shahroud 17, Rabie, Mengha, and Sangi Shireen, were collected in order to evaluate their sensitivity to fungal colonization and the sporulation rate of fungus on them. The results of statistical analysis showed that on the third, fifth, and seventh days, Shahroud 12 was the least resistant cultivar [average pollution (99.5%)], whereas Shahroud 6 was the most resistant [average contamination (7.36%)] at a level of 5 % for growth of A. flavus after 7 days. Experiments related to the testa of almond show that the testa can be a barrier against penetration of fungus into the inner part of the almond, decreaseing fungal growth, and thus reducing the weight of mycelium and sporulation in almonds. تفاصيل المقالة