مقدمه:‌ آفلاتوکسین‌ها متابولیت‌های ثانویه‌ای هستند که توسط برخی گونه‌های قارچ آسپرژیلوس در محصولات کشاورزی تولید شده و به دلیل اثرات جهش‌زایی و سرطان‌زایی در مصرف‌کنندگان از نظر بهداشتی، پزشکی و اقتصادی اهمیت زیادی دارند. هدف از این تحقیق مقایسه پرتوهای فرابنفش و تنگستن در کاهش آفلاتوکسین B1 در محیط آرد برنج می‌باشد. مواد و روش‌ها: آرد برنج آلوده شده با دو غلظت 50 و ng/g 100 از آفلاتوکسین B1 تولید شده توسط قارچ Aspergillus flavus در آزمایشگاه، در 5 زمان 10، 20، 30، 40 و50 دقیقه و 2 فاصله 7 و 14 سانتیمتر از منبع نور فرابنفش با طول موج 366 نانومتر و تنگستن 100 وات مورد پرتودهی قرار گرفت. سنجش آفلاتوکسین با استفاده از روش الایزای رقابتی و در دو تکرار انجام شد. میزان آفلاتوکسین با نمونه‌های شاهد با استفاده از نرم افزار تجزیه آماری SAS نسخه 9.1 توسط آزمون دانکن مورد مقایسه قرار گرفت. یافته‌ها:نتایج نشان داد حداکثر (67 و 68%) و حداقل (14 و 18%) کاهش آفلاتوکسین B1 بعد از 50 و 10 دقیقه پرتودهی در فاصله 7 و 14 سانتیمتری به ترتیب توسط نور فرابنفش و تنگستن اتفاق می‌افتد. غلظت اولیه آفلاتوکسین B1 در نمونه‌های مورد بررسی تأثیری در میزان کاهش آفلاتوکسین بعد از پرتودهی نداشت اما کاهش فاصله تا منبع نور و افزایش زمان در معرض نور قرارگرفتن، موجب کاهش بیشتر آفلاتوکسین گردید (P≤0.01). نتیجه‌گیری: هرچه فاصله بین آرد برنج آلوده به آفلاتوکسین B1 به منبع نور فرابنفش و تنگستن کمتر باشد کاهش آفلاتوکسین در اثر پرتودهی بیشتر رخ می‌دهد. در ضمن هرچه مدت زمان در معرض پرتو قرار گرفتن بیشتر باشد کاهش آفلاتوکسین هم بیشتر می‌شود. استفاده از این پرتوها در کاهش آلودگی مواد غذایی به آفلاتوکسین می‌تواند مورد توجه قرار گیرد. تفاصيل المقالة

مقدمه: نامناسب بودن شرایط انبار ممکن است منجر به ایجاد یا افزایش آلودگی به کپک‌ها و زهرابه‌های ناشی از آن‌ها از جمله آفلاتوکسین گردد. عوامل مختلف محیطی روی رشد قارچی و تولید مایکوتوکسین‌ها به عنوان متابولیت‌های ثانویه مضر مؤثر است. بهبود وضعیت انبار می‌تواند در جلوگیری از آلودگی پسته مؤثر باشد. مواد و روش‌ها: عوامل محیطی تأثیرگذار روی آلودگی پسته در انبارها شامل رطوبت نسبی، دما، رطوبت مغز پسته، فعالیت آبی و آلودگی به آفات در 47 انبار مختلف در شهرستان‌های رفسنجان، کرمان، سیرجان و زرند در فواصل سه ماهه به مدت یک سال بررسی گردید. یافته‌ها: دامنه فعالیت آبی (aW) و رطوبت مغز پسته طی نمونه‌برداری به ترتیب از 46/0 - 12/0 و 3/5 - 1/3 درصد در انبارهای مختلف متغیر بود. در غالب انبارهای مورد بررسی دامنه رطوبت نسبی انبارها از 24 تا 26 درصد متغیر و کمینه و بیشینه آن به ترتیب 13 و 5/36 درصد و دامنه دما بین 3/23 تا 1/26 درجه سانتی‌گراد بود. از طرف دیگر تغییرات رطوبت مغز پسته و فعالیت آبی با گذشت زمان انبارداری در تمامی انبارها تقریباً ثابت بود، لذا تبادل رطوبتی بین پسته و محیط به اندازه‌ای نیست که بتواند رشد قارچ Aspergillus flavus و تولید آفلاتوکسین را افزایش دهد. وضعیت آلودگی میوه پسته به آفات انباری کمتر از 1 درصد و آلودگی به گونه‌های آسپرژیلوس موجود در انبارهای مختلف از غیرقابل تشخیص تا یک درصد در بیش‌ترین مقدار خود متفاوت بود. نتیجه‌گیری: وضعیت کلی انبارهای استان کرمان به صورتی نیست که باعث ایجاد یا بهبود شرایط مناسب برای رشد قارچ و تولید آفلاتوکسین گردد. تفاصيل المقالة

The study was performed to investigate the Aspergillus growth and aflatoxin production in fresh pistachios stored in different packagings. Forty kg of fresh pistachios of the Abbasali cultivar were sampled and kept in different temperature conditions including 4°C and ambient conventional temperatures in plastic baskets or polyethylene plastic bags. Sub-samples were taken at 4 days intervals for 32 days to measure aflatoxin and evaluate the population of Aspergillus section Flavi. Aflatoxins were quantified by HPLC and the fungal population was monitored by dilution series method and AFPA medium. The results showed that on the first day of storage in all conditions the amount of aflatoxin was undetectable. Aflatoxin infection started on the fourth day after storage in the ambient conventional temperature and increased over time. The lowest production of aflatoxin B1 was in the 4°C treatment. Pistachios stored at ambient conventional temperature and packed in plastic baskets showed the highest amount of aflatoxin B1 production. The effect of the treatments on the production of aflatoxin B1 showed that the samples in polyethylene plastic bags at ambient temperature were the highest. The results showed that in the 4°C treatment, the fungal population was significantly less than in ambient temperature treatments. The lowest fungal population was in the 4°C plastic baskets packaged treatment. This treatment was not significantly different from the 4°C polyethylene bag treatment but was significantly different from other treatments (P≤0.01). In general, keeping fresh pistachio at 4°C and suitable plastic is trustworthy. Storage for more than 8 days in the ambient conventional temperature greatly increases the risk of fungal and aflatoxin contamination. 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

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

Aflatoxins, are very toxic mixture and having the potential to cause cancer, produce by some the fungi, mostly Aspergillus flavus and Aspergillus parasiticus, during their growth, harvest and storage on crops such as wheat, corn, cottonseed, peanut, pistachio, etc. For appraising the reaction of maize varieties to A. flavus growth and produced aflatoxin, five varieties of maize, namely KSC400, KSC403, KSC600, KSC703, KSC704, were selected. An isolate A. flavus that produce afalatoxin was used for inoculation of maize kernels (as in vitro conditions). In a statistic completely random design with three replications, 10 gr of kernels of selected cultivars were inoculated with 1×106 spores/ml of fungal spore suspension. After eight days, the percentage of fungal growth and the colonization of maize kernels were calculated. The aflatoxin B1 produced in contaminated all maize cultivars were measured with high performance liquid chromatography (HPLC). Statistical analyses showed a significant difference (α=0.05) between the fungal growth percentages and the amount of aflatoxin B1 in the kernels of tested maize cultivars. Also, the results showed that among mentioned varieties, KSC600 was the least susceptible variety to the growth of Aspergillus. The amount of produced aflatoxin B1 was variable among the varieties. KSC600 had the least whereas KSC403 had the highest rate of aflatoxin B1 content. تفاصيل المقالة

Infection of pistachio nuts with Aspergillus flavus and aflatoxin is one of the serious and important threats in the process of production, export, and consumption of pistachios in the world. Aflatoxins are secondary metabolites that are mainly produced by A. flavus and A. parasiticus. Aflatoxins are generally produced before harvesting and under horticultural conditions. Early-splitting pistachios are one of the most significant sources of contamination to aflatoxigenic fungi in the orchard. In the present study, the population density of Aspergillus section Flavi and aflatoxin content were investigated in early-splitting, irregular cracking, and intact pistachios of the Shahpasand cultivar. Sampling was done from the pistachio orchard of Damghan Pistachio Research Station in the first half of August, and pistachio kernel contamination and population density of the fungus were investigated. Pistachio samples were cultured on an AFPA medium using a serial dilution method (completely randomized design with three repetitions). Aspergillus section Flavi colonies were identified and counted and after three days at 28°C and dark. Aflatoxin contents of pistachio kernels were quantified by high-performance liquid chromatography (HPLC) method. The results were statistically analyzed by SPSS statistical software and the means were compared using Duncan's multiple range test. The results showed that the highest and the lowest contamination rates for Aspergillus section Flavi and aflatoxin have belonged to early-splitting and intact nuts, respectively (P≤0.05). The contamination rate in early splitting pistachios is much higher than in irregular cracking and intact kernel pistachios. تفاصيل المقالة

سفیدک داخلی مهم‌ترین بیماری اندام‌ هوایی خیار در کشت‌های گلخانه‌ای است. این بیماری توسط گونه Pseudoperonospora cubensisبه وجود آمده و در صورت عدم کنترل خسارت زیادی وارد می‌کند. اثر قارچ‌کش‌های سیازوفامید (رانمن^®% SC 34.5)، پتاسیم فسفیت (فسفیت^®WSL 53 % )، فلوپیکولید+ پروپاموکارب (propamocarb hydrochloride 625g/l + fluopicolide 62.5 g/l) (اینفینیتو^® (68,75 SC و فاموکسادون + سیموکسانیل (اکوییشن‌پرو^®WG 52.5%) در کنترل بیماری سفیدک داخلی خیار در گلخانه‌ای در اربطان مرند (آذربایجان شرقی) با سابقه آلودگی به بیماری ارزیابی شد. آزمایش با 11 تیمار و چهار تکرار در قالب طرح کاملاً تصادفی در سال 93 انجام گردید. تیمارهای آزمایش، قارچ‌کش­های رانمن به میزان 2/0، 3/0 و 4/0 در هزار، فسفیت به میزان 2، 3 و 4 در هزار، اینفینیتو به میزان 25/1، 5/1 و 2 در هزار، اکوییشن‌پرو به میزان 3/0 در هزار ، و شاهد بدون سم‌پاشی بودند. سم‌پاشی کرت‌های آزمایشی بعد از مشاهده اولین علایم بیماری در سه نوبت با فاصله زمانی 10 روز انجام و آماربرداری ازکرت‌های آزمایشی، هفت روز بعد از آخرین سم‌پاشی انجام شد. شدت آلودگی برای هرکرت براساس میزان لکه روی سطح برگ و تشکیل و یا عدم تشکیل اسپورانژیوم محاسبه شد. تجزیه آماری داده‌ها با نرم افزار SPSS و مقایسه میانگین‌ها با آزمون چند دامنه‌ای دانکن انجام گرفت. نتایج نشان داد که بهترین اثر کنترل بیماری مربوط به تیمارهای رانمن 4/0 در هزار، فسفیت 4 در هزار و اینفینیتو 2 در هزار به ترتیب با شدت بیماری 3/3، 53/7 و 69/8 درصد نسبت به 79 درصد در تیمار شاهد بود (P≤0.01). بدین ترتیب این قارچ‌کش‌ها می‌توانند در گلخانه بصورت متناوب مورد استفاده قرار گیرند. تفاصيل المقالة