مقدمه: پسته‌های زودخندان از مهم ترین منابع آلودگی پسته به آفلاتوکسین در باغ و مراحل فرآوری این محصول به شمار می‌روند. در این پژوهش ویژگی‌های مختلف پسته‌های ترک‌خورده و میزان آلودگی آنها به قارچ‌ها و آفلاتوکسین مورد بررسی قرار گرفته است. مواد و روش ها: ویژگی‌های مختلف پسته‌های زودخندان شامل خصوصیات ظاهری، آلودگیبه قارچ‌های گروه ‌AspergillusflavusوA. niger و مقدار آفلاتوکسین با روش‌های مختلف مورد بررسی قرار گرفت. آزمایشات روی سه رقم تجاری پسته شامل اوحدی، کله قوچی و احمد آقایی از دو باغ مختلف انجام گرفت و نتایج حاصل در قالب طرح بلوک‌های کامل تصادفی با استفاده از نرم افزار Mstatc تجزیه و تحلیل آماری شد. یافته‌ها:از نظر کلی بیشترین میزان آلودگی به گونه‌های مختلف قارچ آسپرژیلوس مربوط به پسته‌های زودخندان با پوست سبز خشک و نیمه‌خشک با دامنه تغییرات 1/4 تا 66/5% بود. پسته‌های زودخندان با پوست سبز خشک و نیمه‌خشک همچنین بیشترین فراوانی آلودگی به شب‌پره خرنوب (1/9-54/5%) و رنگ‌گیری پوست استخوانی (30-86%) و کمترین وزن مغز (0-0/3 گرم در دانه) را به خود اختصاص دادند. میوه‌های پسته زودخندان با پوست نرم رویی نیز سطوح مختلفی از آلودگی را نشان دادند که میزان آلودگی قارچی در آنها از 0/75 تا 10/3%، شب‌پره ‌خرنوب 1/5 تا 9/5% و میزان رنگ‌گیری 21/5 تا 44/1 متغیر بود.این موضوع نشان دهنده اهمیت پسته‌های زودخندان و زمان تشکیل آنها در ریسک آلودگی میوه پسته به آفلاتوکسین می‌باشد. آلودگی به شب‌پره‌خرنوب باعث افزایش سطوح آلودگی به‌ قارچ‌های گروه ‌ A. flavusوA. niger شده بود. آلودگی به قارچ‌ها، شب‌پره خرنوب و مورچه باعث کاهش وزن مغز میوه های پسته گردیده بود.نتایج نشان داد که پوست سبز پسته عاری از آفلاتوکسین‌ها می‌باشد، در حالی‌که پوست استخوانی و مغز حاوی سطوح متفاوت آفلاتوکسین‌ها بودند. مقایسه توانایی تولید آفلاتوکسین در جدایه‌ها مشخص نمود که 67 درصد جدایه‌ها تولید آفلاتوکسین های B1 و B2، 24 درصد تولید آفلاتوکسین B1 و 9 درصد قادر به تولید آفلاتوکسین نبودند. نتیجه‌گیری: استفاده از خصوصیات ظاهری و فیزیکی پسته‌های آلوده جهت جداسازی آنها در فرآوری و یا پس از آن می تواند در کاهش سطوح آلودگی پسته‌های فرآوری شده موثر واقع گردد. نتایج نشان دهنده ‌نقش کلیدی برداشت زودتر در کاهش سطوح آلودگی و مقدار آفلاتوکسین می‌باشد. حدود 95 و 5 درصد از آفلاتوکسین اندازه گیری شده به ترتیب مربوط به مغز و پوست استخوانی بود و برای اندازه‌گیری دقیق آفلاتوکسین بهتر است پوست استخوانی از سنجش‌های مربوطه حذف گردد. تفاصيل المقالة

پسته به‌عنوان مهمترین محصول کشاورزی صادراتی کشور شناخته می‌شود که به‌رغم اهمیت راهبردی آن، چالش‌های بسیاری در مسیر تولید و ارایه آن به مصرف‌کننده وجود دارد. میوه پسته بستر مناسبی برای رشد کپک‌های مولد توکسین از جمله گونه‌های آسپرژیلوس است. هدف از این تحقیق مقایسه میزان آفلاتوکسین در قسمت‌های مختلف میوه، قبل و بعد از برداشت و در انواع پسته‌ها بود. برای این هدف، از میوه‌های سالم و زودخندان قبل از برداشت در مرحله باغ و همچنین از مراحل مختلف فرآوری میوه پسته در ترمینال‌های فرآوری، نمونه‌برداری صورت گرفت. مقدار آفلاتوکسین B1 در نمونه‌ها با استفاده از کیت تشخیص الایزا اندازه‌گیری گردید. میانگین مقدار آفلاتوکسین در مغز پسته‌های زودخندان و سالم نمونه‌برداری شده قبل از برداشت به‌ترتیب 2/10 و 8/1 (ng/g) بود. انواع پسته‌های فرآوری شده سطوح متفاوتی از مقدار آفلاتوکسین را نشان دادند و مقدار آفلاتوکسین در پسته‌های لکه‌دار، ریز، روآبی و خندان به‌ترتیب 21، 4، 15 و 2 برابر بیشتر از پسته‌های بدون لکه، درشت، زیرآبی، و غیرخندان بود. وجود آفلاتوکسین در نمونه‌های پسته در باغ و نمونه‌های فرآوری‌شده نشان‌دهنده آلودگی به قارچ‌های مولد آن تحت شرایط باغی است، که در صورت فراهم شدن شرایط مناسب بعد از برداشت نیز می‌تواند گسترش یابد. با شناسایی و جداسازی منابع آلودگی در مراحل اولیه و پس از فرآوری در یک توده پسته می‌توان سطح آلودگی به آفلاتوکسین را کاهش داد و پسته عاری از آلودگی تولید نمود. تفاصيل المقالة

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

Aflatoxins are secondary metabolites, which have documented in food and feed such as pistachio.Application of incorrect cultural practices such as animal manures resulted in increasing the density of Aspergillus section Flavi propagules and as consequences increase in aflatoxin content in pistachio nuts. Here, the density of Aspergillus section Flavi propagules, aflatoxin kernel content and characteristics of pistachio fruits in soil surface and fertilizer cannel applications of poultry manure in the orchards in randomized complete block design were compared with control treatment (without poultry manure application). Application of poultry manure on soil surface increased Aspergillus section Flavi propagulesby 4.5 and 11 times higher than compare to those treatments either which not received or in fertilizer channels, respectively. Aflatoxin content in pistachio nuts decreased by 85 and 51 % where poultry manures applied in fertilizer channels and no application compared to surface application, respectively. Overall, poultry manure in fertilizer channel reduced the frequency of blank fruits as well as increasing of splitted nuts and the nuts’ sizes. تفاصيل المقالة

The economic importance along with the high nutritional value of pistachio has necessitated further research on this agricultural product. Its contamination with various microorganisms causes several problems for the production, consumption and export of pistachio every year. Pistachio as a fatty nut is very susceptible to fungal and bacterial contamination and thereby, its shelf life would be reduced. Peracetic acid is a strong oxidizer which can rapidly remove a wide range of microorganisms and is also environmentally safe. In this research, pistachio seeds were firstly treated with different concentrations (0, 1, 2 and 2.5%) of peracetic acid for 0.5, 1, 1.5, 2 and 5 min. Then the growth of fungi and bacteria were evaluated. The results indicated that 2% peracetic acid for 0.5 min led to 99% reduction in contaminating microflora . In the next step, the most common microflora contaminating pistachio seeds were detected and exposed to different concentrations of peracetic acid for 0.5, 1, 1.5, 2 and 5 min. The results showed that 1% peracetic acid for 0.5 min inhibited the growth of the dominant microflora more than 99%. Peracetic acid treatment in the tested range had no significant effect on lipid content but reduced peroxide value. Therefore, disinfection of pistachio product with a concentration of 1-2% peracetic acid in the washing basins of pistachio processing terminals may be an applicable approach to inhibit their microbial (bacteria and fungi) contamination up to 99% and improve their quality before introducing to the market. However, this idea requires further field research. تفاصيل المقالة

Aflatoxin is an important fungal contaminant in various crops. The substrate and its compounds are involved in the growth of fungus and the production of toxins. In order to investigate correlation between sugar and lipid content as the major chemical composition of pistachio kernels with Aspergillus flavus growth and aflatoxin production, the total sugar content was extracted by phenol-sulphoric method and estimated by spectrophotometry. The lipid was also extracted by Soxhlet method. A toxigenic A. flavus strain was used for the study of the fungal growth and aflatoxin B1 production. For that, 20 gram of kernels of different pistachio cultivars were inoculated with 1 ml of fungal spore suspension (2×106 spores/ml) in a completely randomized design with three replications. Eight days after inoculation, the average percent of fungal growth and colonization of A. flavus were calculated. The aflatoxin produced in inoculated pistachios was extracted by Best Foods (BF) method and measured by thin layer chromatography (TLC). The results showed that there was no significant difference in the amount of sugar content in different cultivars of pistachios kernel but the amount of total lipid content was different (P≤0.05). Results of statistical analysis showed that there was no significant correlation between sugar content with fungal growth and aflatoxin production in pistachio cultivars as well as lipid percentage and aflatoxin B1 production. Therefore, to find sources of resistance to A. flavus in commercial pistachio cultivars in aflatoxin management programs, these two factors cannot be used as a standard scale of resistance. تفاصيل المقالة

Application of sulfur to control the common pistachio psylla has been nowadays popular. The psylla is one of the main pistachios’ pests. Aspergillus flavus, the most important aflatoxin producer, has a strong impact in the mycoflora of pistachio orchards. The present study has been conducted to determine the effects of sulfur on A. flavus. Therefore, a toxigenic A. flavus strain was cultured on potato dextrose agar (PDA) medium, and the effects of mineral sulfur, refinery sulfur and sodium metabisulfite were closely monitored on fungal mycelial dry weight, germination of spores, germ tube and mycelium germination. The Fungal parameters measurement for sulfur vapor exposure and sulfur addition to the culture medium declared no significant effect on the growth of A. flavus mycelium in the direct addition. But sulfur in liquid medium as well as in high concentrations caused mycelial dry weight loss. Importantly, the sublimation of 0, 0.5, 1, 2, 5, 10, 25 and 50 gm-3 from the refinery sulfur, prevented completely the growth of germinated spores and mycelial. Significantly, the complete inhibition of spore germination was observed at a concentration level of 2 g m-3 and also sodium metabisulfite prevented the growth of A. flavus at a concentration of 15 g l-1 culture medium. The sulfur usage in culture medium declared no inhibition of A. flavus growth, but at high concentrations in liquid medium, it reduced mycelial dry weight. Therefore, it is found that the sulfur application in any kind to control of psylla would not probably effect significantly on the aflatoxigenic A. flavus. تفاصيل المقالة

Pistachio dieback (DBP) is a significant disease affecting pistachio trees in Iran, and it has emerged as a serious problem in Kerman province in recent years. This study investigates the role of bacteria as causal agents of DBP under laboratory and field conditions. Samples were collected from infected pistachio orchards in Kerman province from 2015 to 2016. The ability of bacterial isolates to induce disease and colonize vascular tissues was studied using various inoculation methods. Identification of isolates was carried out using biochemical and physiological assays, amplification of the 16S rDNA region, and partial analyses of the gyrA gene. A total of 281 bacterial isolates were obtained from infected trees, of which 148 induced a hypersensitivity reaction on tobacco leaves. Among these, 128 isolates were able to colonize vascular tissues in sub-bark inoculations of pistachio branches under laboratory conditions. In field experiments, 24 selected isolates were able to spread in vascular tissues of pistachio branches and twigs using sub-bark and apical inoculation methods, although disease severity varied. Staphylococcus pasteuri, Bacillus pumilus, Bacillus sp., Acinetobacter radioresistens, Xanthomonas sp., Curtobacterium flaccumfaciens, Pseudarthrobacter oxydans, and Pseudomonas koreensis were identified as being involved in the dieback of pistachio trees. This work demonstrates that a wide range of bacterial genera and species may be involved in DBP, and urgent strategies should be considered for managing the disease. تفاصيل المقالة

In this study, the effect of 13 fungicides on mycelial growth, spore germination and sporulation of Paecilomyces formosus, the main causal agent of dieback disease, were investigated in vitro and in vivo. Treatments included Profiler®, Rovral-TS®, Elit®, Oxychromes®, Cidley Top®, Cuprosit C®, Ortivatop®, Captan®, Acrobat MZ®, Benomyl®, Luna®, Folicur® and Falcon® at different concentrations of 500-3000 ppm. The results showed that the efficiency of different fungicides on fungal development, measured as mycelial growth, spore germination ranged from 36.8 to 100% and 21.7 to 100%, respectively. The inhibition of sporulation was between 0 to 4.3×106 spores mL-1. In vitro, the highest reduction in mycelium growth and spore germination was observed for the fungicides Benomyl®, Luna®, Folicur®, and Falcon® at concentrations of 1000, 500, 1500, 2000 and Ortivatop®, Elite®, Falcon®, Benomyl®, Captan®, and Acrobat MZ® at concentrations of 750, 2500, 2000 1000, 3000, 3000 ppm, respectively. In vivo, the effect of selected fungicides was evaluated on inoculated shoots. The rate of inhibition of pathogen progression using immersion inoculation and the vertical method was 18.7-43.2% and 39.8-45.5%, respectively. The highest inhibition (45.5%) was observed with Luna® fungicide at 500 ppm using the vertical method and the lowest inhibition (18.7%) was related to Benomyl fungicide at 1000 ppm using the immersion method (P≤0.01). No significant advantages were observed in fungicides applications in terms of DBP control compared to those control trees with no-spraying fungicides. In contrast, pruning showed comparative advantages in the management of DBP. تفاصيل المقالة

Several species of Phytophthoracause crown and root rot diseases of herbaceous and woody plants.Crown and root rot of pistachio trees cause significant damages in infected orchards. The effect of foliar application with Elite (fosetyl-Al) in 2 and 2.5 g/l was evaluated in greenhouse experiments. The frequency of mortality, fresh and dry weight of roots and shoots, height, intensity of crown root colonization using CAMA-PARP medium was determined. Under greenhouse experiments, foliar application with Elite increased height, fresh and dry weight of shoots and root either in inoculation with and without Phytophthora drechsleri. The effects of Elite were more pronounced in roots, which increased the fresh and dry weight of root 1.3 and 2.5 times compared to those not sprayed with Elite, respectively. On the other hand, the application of Elite before or on the day of inoculation significantly reduced the frequency of mortality, which ranged from 35 to 90% (P ≤ 0.01). Crown and root colonization of pistachio seedling was affected by both the concentration of Elite and reduced the frequency of crown and root colonization of seedling. When fungicide and pathogen were applied at the same time, the frequency of colonization reduced to 18% and 36% for 2 and 2.5 g/l, respectively, and 43% and 60% when seedlings were treated with fungicide before P. drechsleri inoculations. The highest effect was seen in foliar application of Elite seven days before inoculation in 2.5 g/l. Further investigations have been conducted to understand the effect of Elite in infected trees as well as modeling of Elite application via soil drench, foliar application or trunk injection. تفاصيل المقالة

Root and crown rot (gummosis) is known as the most destructive disease affecting pistachio in Iran. The efficiency of bacterial strains to reduce the growth rate of Phytophthora pistaciae was studied under different electrical conductivities (EC, 0, 2, 4, 8, 12 ds/m). Soil and rhizosphere samples were collected from pistachio growing regions in Kerman province, Iran, during 2011 - 2012. Overall, the strains of bacteria were presented in all sampling areas in both infected and uninfected orchards. Out of 400 bacterial isolates, 63% and 37% were collected from soil and rhizosphere samples, respectively. Among 400 bacterial isolates, 19 exhibited the highest ability to reduce the growth of P. pistaciae in dual culture, volatile and non-volatile compounds, though by different degrees. The degrees of inhibitory activities against mycelial growth of P. pistaciae by Pseudomonas fluorescens strains ranged from 40 to 97.5%, 8 to 97.5% and 7.5 to 90% in dual culture, non-volatile and volatile assays, respectively. The Bacillus subtilis strains reduced the growth of P. pistaciae by 22-92.5%, 17-85%, 21-92.5% in dual culture, non-volatile and volatile assays, respectively. The negative effects of ECs on the growth of P. pistaciae in modified CMA were observed in 8 and 12 ECs. ECs had no effect until 8 ds/m on the growth of P. pistaciae, while the mycelial growth decreased by ECs higher than 8 ds/m. No mycelial growth was observed at EC 14 ds/m. There were significant differences between different bacterial isolates, ECs and their interactions on the mycelial growth of P. pistaciae. The highest mycelial suppression belonged to isolates Nos. 123 and 112 in dual culture, volatile and non-volatile compounds test. More research is required to understand the native mechanisms involved in biological control under natural conditions in pistachio orchards تفاصيل المقالة

Research in plant disease management focuses on developing safe methods for humans and the environment in order to prevent the entry of harmful chemicals in food. Simple inorganic salts have low cost and are safe enough to be used as pesticides. Phytophthora genus causes crown and root rot (gummosis) in crops and leads to great losses in some pistachio (Pistacia vera L.) production areas annually. In this study, the potential efficacy of different calcium salts with various concentrations on Phytophthora pistaciae control was examined. This was done to find out a safe way of material usage instead of synthetic pesticides. Samples from the crown of a pistachio tree, with gummosis, were cultured on lima bean agar to isolate and purify the pathogen. P. pistaciae identification was done using the PCR method with ITS4 and ITS6 primers. Pathogenicity of isolate was confirmed through tests on apples, pistachio branches, and pistachio seedlings. Different concentrations of seven calcium salts (chloride, nitrate, sulfate, oxide, hydroxide, phosphate, and carbonate) were applied which reduced mycelial growth and 3000ppm of calcium oxide inhibited it completely. Most of the salts reduced the number of sporangia, zoospores, and cyst germination percentage. Calcium oxide and calcium hydroxide also caused hyphae branching and deformation of some sporangia. The results suggested that some calcium salts, especially calcium oxide, could control the growth of P. pistaciae in vitro. Future in vivo studies are needed to examine whether calcium salts can reduce the disease severity and spread of the pathogen in the environment if those are sprinkled over the soil around the infested crown. تفاصيل المقالة

Application of atoxigenic strains of Aspergillus flavus to reduce aflatoxin levels is the most successful strategy applied in some agricultural crops. The role of ammonium hydroxide for preliminary screening of the competitiveness of atoxigenic A. flavus isolates to interfere with aflatoxin production by highly toxigenic isolates were evaluated. Out of 270 A. flavus isolates, 17 were detected as true atoxigenic using cultural methods and confirmed by analytical assays from different pistachio agro-ecological zones during 2013. For assessment competitive ability among atoxigenic isolates of A. flavus with highly toxigenic one, rice flour, coconut agar and coconut broth medium substrates were inoculated with mixtures including combinations of toxigenic and atoxigenic isolates, simultaneously. The rice flour substrate was used to quantify the content of aflatoxin in either co-inoculations or toxigenic isolate alone on thin layer chromatography plates with a scanning densitometer. While the culture media were used to determine the intensity of color change on exposing to ammonium hydroxide vapor. The reduction rates of aflatoxin B1 in co-inoculations were varied and ranged from 2%-82%. Based on the intensity of colony color changes, the competitiveness of the isolates was classified into five groups. Atoxigenic isolates with high competitiveness have shown low color changes in culture media and high aflatoxin reduction in TLC assays with a ratio of higher than 78%. The method will facilitate preliminary screening of efficient atoxigenic isolates for mitigation of aflatoxins in food and feed as a cheap, simple and quick method. تفاصيل المقالة