فهرست مطالب

مطالعات حفاظت گیاهان - سال سی و سوم شماره 1 (بهار 1398)
  • سال سی و سوم شماره 1 (بهار 1398)
  • تاریخ انتشار: 1398/03/11
  • تعداد عناوین: 12
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  • فاطمه زرندی *، فرهاد شکوهی فر، بهرام شریف نبی، بدرالدین ابراهیم سیدطباطبایی، ضیاء الدین بنی هاشمی صفحات 1-8
    قارچ های بیماریزای گیاهی جهت غلبه بر سیستم دفاعی گیاه از ابزار مختلفی بهره می گیرند. ترکیبات فیتوآنتیسیپین از جمله مواد دفاعی است که در گیاه جهت جلوگیری از حمله بیمارگرها تولید می شود. آنزیم توماتیناز جهت تجزیه فیتوآنتیسیپین و غلبه بر سیستم دفاعی گیاه توسط طیفی از قارچ ها از جمله تعدادی از فرم های اختصاصی قارچ F. oxysporum تولید می شود. با هدف ردیابی توالی کد کننده آنزیم توماتیناز در فرم اختصاصی Fusarium oxysporum f. sp. melonis (Fom) آغازگرهای اختصاصی بر اساس توالی محافظت شده بالادست و پائین دست توالی کدکننده ژن FoTom1 گزارش شده از فرم اختصاصیFusarium oxysporum f. sp. lycopercisi (Fol). طراحی شد. استخراج DNA از نژاد یک، شایع در استان خراسان، انجام شد و واکنش تکثیر با استفاده از آغازگرهای اختصاصی صورت گرفت. الگوی الکتروفورزی محصول واکنش حضور یک تک باند در اندازه مورد انتظار را تایید نمود. قطعه تکثیر شده بصورت دو جهته توالی یابی شد و با توالی گزارش شده از فرم اختصاصی Fol مورد مقایسه قرار گرفت. نتایج توالی یابی با استفاده از برنامه Vector NTi V11 بر هم منطبق شد و با توالی رفرنس همردیفی انجام شد. نتایج نشان داد در سطح نوکلئوتیدی 14 جهش در توالی شناسائی شده وجود دارد که از این بین 7 جهش در سطح توالی پروتئینی نیز بروز می یابند. آنالیز توالی با استفاده از برنامه Pfam وجود یک توالی سیگنال پپتید و یک دومین هیدرولازی را در توالی شناسائی شده تایید نمود. این نتایج نشان داد که توالی ردیابی شده میتواند همولوگ ژن توماتیناز در ژنوم فرم اختصاصی Fom باشد. این توالی Fom-Tom نامگذاری شد و در بانک ژن با شماره بازیابی MF178403 ثبت شد. با هدف پیش بینی اثر جهش ها شناسائی شده در عملکرد ژن توماتیناز آنالیزهای نرم افزاری انجام شد که نشان داد جهش های رخ داده در توالی دومین هیدرولازی ساختمان پروتئین را تحت تاثیر قرار می دهند و می توانند در عملکرد ژن تاثیرگذار باشند.
    کلیدواژگان: بیماری زردی و پژمردگی آوندی خربزه، خربزه، ردیابی ژن، ژن توماتیناز
  • فرشته اسمعیل زاده میان لنگه، سید مهدی بنی هاشمیان *، احمد روحی بخش، سیروس آقاجانزاده صفحات 9-16
    ویروس تریستزای مرکبات (virus; CTV Citrus tristeza)، عامل مهم ترین بیماری ویروسی مرکبات است و شته جالیز (Aphis gossypii) به عنوان ناقل کارای این ویروس در ایران معرفی شده است. در این تحقیق، روش های مختلف ردیابی ویروس تریستزای مرکبات در شته جالیز با استفاده از جدایه SD4 از کلکسیون ویروسی پژوهشکده مرکبات و میوه های نیمه گرمسیری مورد ارزیابی قرار گرفت. کلنی خالص این شته ابتدا به مدت 48 ساعت روی منبع آلوده به ویروس و سپس روی گیاهچه های لیموترش مکزیکی (aurantifolia Citrus) تحت شرایط کنترل شده قرار داده شد. حضور ویروس در گیاهان گیرنده پس از سه ماه بر اساس علایم و روش سرولوژی ایمیونوپرینت (Direct tissue blot immuonoassay) تشخیص داده شد. آلودگی این گیاهان با استفاده از Reverse transcription polymerase chain reaction; RT-PCR دو مرحله ای با جفت آغازگرهای اختصاصی پوشش پروتئینی T36CPF/T36CPR بر اساس اسیدریبونوکلئیک استخراج شده به روش SDS-Potassium acetate از بافت گیاهی مورد تایید قرار گرفت. در تشخیص مستقیم ویروس از شته، RT-PCR یک مرحله ای و اسیدریبونوکلئیک استخراج شده از شته ها به روش ترایزول به کار گرفته شد و باندهای خفیفی به اندازه 672 جفت باز به دست آمد. با انجام مرحله دوم PCR، براساس فرآورده به دست آمده از مرحله اول و با استفاده از جفت آغازگرهای T36CPF/P25R، قطعات مشخص با اندازه 362 جفت باز حاصل گردید. در حالی که RT-PCR آشیانه ای (RT-nested-PCR) با ترکیب آغازگرهای PexF/PexR-PinF/PinR، به دلیل ایجاد مثبت کاذب در شرایط مطالعه حاضر قادر به ردیابی ویروس در شته های آلوده نبود.
    کلیدواژگان: آزمون بیولوژی، تشخیص مستقیم، شته ناقل، ویروس تریستزا
  • مرتضی گل محمدی * صفحات 17-21
    بیماری لکه سبز مرکبات (گرینینگ) توسط سه گونه باکتری به نام های Candidatus Liberibacter asiaticus، Ca. L. africanus و Ca. L. americanus ایجاد می شود. دو گونه پسیل مرکبات به نام های پسیل آسیایی Diaphorina citri و پسیل آفریقایی Trioza erytreae باکتری عامل بیماری را منتقل می کنند. علاوه بر پسیل، از طریق منابع تکثیری آلوده و استفاده از پیوندک آلوده نیز منتقل می شوند. به منظور ردیابی عامل این بیماری، نمونه های برگی و میوه های مشکوک به آن از جنوب کرمان جمع آوری گردید. در 12 نمونه از 48 نمونه بررسی شده، وجود بیماری تایید شد. توالی یابی محصول پی سی آر (ناحیه ریبوزومی) به طول 1077 جفت باز و مقایسه آن با استرین کنترل مثبت استاندارد و همچنین تولید دو قطعه 640 جفت باز و 520 جفت بازی این ناحیه با هضم آنزیمی توسط XbaI نشان داد که عامل بیماری لکه سبز مرکباتCandidatus Liberibacter asiaticus (تیپ آسیایی) است. جدایه های مورد بررسی در این مطالعه با وجود بروز علایم متفاوت، با یکدیگر و با جدایه استاندارد قرابت کامل نشان دادند.
    کلیدواژگان: پی سی آر، تشخیص، تیپ آسیایی، Candidatus Liberibacteri asiaticus
  • مهند الجابری، محسن مهرور*، محمد زکی عقل صفحات 23-26
    ویروس موزاییک رگبرگی اقاقیای زینتی (Wisteria vein mosaic virus,WVMV) یک بیماری ویروسی شایع در گونه ویستریا است. این ویروس عضو جنسPotyvirus از خانواده Potyviridae می باشد. به منظور ردیابی و شناسایی این ویروس در سال های 1397-1396 تعداد 3 نمونه مشکوک اقاقیای زینتی از استان خراسان رضوی جمع آوری شده، جفت نوکلئوتید . محصول PCR مربوط به یک جدایه پس ازهمسانه سازی توالی یابی شده، با سایرتوالی های موجود در بانک ژن مقایسه گردید. نتایج بدست آمده نشان داد که در سطح نوکلوتیدی بیشترین تشابه آن با جدایه چینی این ویروس به میزان 64/90 درصد و کمترین میزان تشابه آن با جدایه ای ازویروس موزاییک کاهو (Lettuce mosaic virus) به میزان 34/56 درصد می باشد.
    کلیدواژگان: آنالیز فیلوژنتیکی، خراسان رضوی، ژن CI، ویروس موزائیک رگبرگی اقاقیای زینتی، RT-PCR
  • صدیقه اشتری* صفحات 27-34
    زنبورهای تریکوگراما از پارازیتوئیدهای مهم تخم بالپولکداران محسوب شده و به طور گسترده ای در کنترل بیولوژیکی آفات به کار گرفته می شوند. در این تحقیق غلظت های توصیه شده مزرعه ای سه حشره کش اسپینوسد، ایمیداکلوپرید و ایندوکساکارب در شرایط نیمه مزرعه ای روی گوجه فرنگی به روش محلول پاشی تا جاری شدن سم به کار برده شد. بر اساس دستور کار گروه IOBC/WPRS به ترتیب در روزهای سوم، پنجم، شانزدهم و سی و یکم پس از سم پاشی از هر تیمار و تیمار شاهد نمونه های برگی جدا شد. ارزیابی اثر تیمار بر اساس مرگ و میر افراد بالغ هر دو گونه زنبور پس از 24 ساعت قرارگیری در معرض باقی مانده سم انجام گرفت و دوام این حشره کش ها علیه مرحله بالغ یا حساس ترین مرحله زندگی دو گونه زنبور تریکوگراما تعیین شد. نتایج آشکار کرد که ایمیداکلوپرید با ایجاد 34/25 و 31/26 درصد مرگ و میر در کمتر از 5 روز در گونه هایT. brassicae و T. evanescens برای هر دو گونه بی دوام بودند. ایندوکساکارب با 13/14 و 35/12 درصد مرگ و میر در کمتر از 16 روز در گونه هایT. brassicae و T. evanescens جزء آفت کش های کم دوام بود. در حالی که اسپینوسد با 31/13 و 65/12 درصد مرگ و میر در کمتر از 30 روز در گونه های T. brassicae و T. evanescens در گروه ترکیبات با دوام متوسط دسته بندی شد.
    کلیدواژگان: پارازیتویید، پایداری، شرایط نیمه مزرعه ای
  • لادن پورسرتیپ *، کوروش سعادت وفا، پژمان رضایتی چرانی صفحات 35-43
    یکی از مهمترین گونه های موریانه در استان های جنوب ایران Microcerotermes diversus Silvestri است که جزء موریانه های زیرزمینی محسوب می شود و توانایی حمله به چوب آلات ساختمانی و حتی درختان سرپا را نیز دارد. با توجه به این واقعیت که بسترهای لیگنوسلولزی می توانند به راحتی توسط موریانه مورد تغذیه قرار گیرند، این امر می تواند موجب آسیب زیادی به چوب آلات ساختمانی گردد، لذا شناسایی گونه های چوبی مقاوم می تواند در انتخاب مناسب این مواد در مناطقی که هجوم موریانه ها بالاست کاربرد داشته باشد. بدین منظور طبق روش استانداردASTM D 3345/1980، دو گونه پهن برگ راش و اکالیپتوس و یک سوزنی برگ زربین انتخاب و نمونه های برش داده شده، طی آزمون های تغذیه ای انتخابی و غیرانتخابی در معرض هجوم موریانه قرار داده شدند. برای بررسی میزان ارتباط جذابیت تغذیه ای چوب ها برای موریانه با خصوصیات فیزیکی و شیمیایی چوب، پارامترهایی مانند درصد مواد استخراجی، جرم مخصوص، میزان لیگنین و سلولز هر کدام از گونه ها طبق استاندارد محاسبه شد. نتایج بدست آمده از آزمون های تغذیه ای انتخابی و غیرانتخابی نشان داد که چوب زربین کمترین و چوب راش بیشترین میزان مطلوبیت برای موریانه را دارند. با توجه به نتایج آنالیز مواد شیمیایی چوب ها، به ترتیب بالاتر بودن درصد لیگنین و مواد استخراجی مانند ایزوفیلوکلادن، بوربونوانون، سینامالدیید هگزا و دکانوییک اسید در گونه های زربین و اکالیپتوس می تواند باعث ایجاد عدم مطلوبیت این گونه ها برای موریانه در مقایسه با راش باشد.
    کلیدواژگان: جرم ویژه، لیگنین، سلولز، ماده لیگنوسلولزی، مواد استخراجی
  • ساناز فرخنده، لیلا علی مرادی *، کیومرث کلارستاقی صفحات 45-55
    به منظور مقایسه اثرات مواد افزودنی سیتوگیت، فریگیت، دی آکتیل، ولک، پروپل و آدیگور هر یک با دو غلظت 1 و 2 درصد در کارایی علف کش توتال، یک آزمایش گلخانه ای واکنش به مقدار علف کش به صورت آزمایش فاکتوریل در قالب طرح کاملا تصادفی با دو فاکتور که فاکتور اول شامل غلظت های صفر، 625/5، 25/11، 50/22، 75/33، 45 گرم ماده موثره در هکتار علف کش توتال و فاکتور دوم در 13 سطح بدون روغن معدنی و با روغن های معدنی آدیگور، پروپل، ولک، فریگیت، سیتوگیت، دی آکتیل و هر کدام با غلظت های 1 و 2 درصد حجمی بر یولاف وحشی در چهار تکرار انجام گرفت. ترتیب قدرت مواد افزودنی مورد مطالعه در کاهش کشش سطحی محلول علف کش توتال به صورت آدیگور < پروپل < ولک < فریگیت < دی آکتیل <سیتوگیت بود. به گونه ای که سیتوگیت در غلظت 2 درصد موجب کاهش 59.71 درصدی در کشش سطحی محلول علف کش شد. در حالی که آدیگور در غلظت 2 درصد موجب کاهش 33.68 درصدی در کشش سطحی محلول علف کش شد. بطور کلی، ترتیب کارایی مواد افزودنی مورد مطالعه در بهبود کارایی علف کش توتال در کنترل علف هرز یولاف وحشی را می توان به صورت آدیگور > پروپل > ولک > دی آکتیل > سیتوگیت > فریگیت بیان نمود.
    کلیدواژگان: آدیگور، کشش سطحی، مواد افزودنی
  • مجید برزوئی، ابراهیم ایزدی دربندی *، محمد حسن راشد محصل، مهدی راستگو، محمد حسن زاده خیاط صفحات 57-67
    تریفلورالین از جمله علف کش هائی است که ماندگاری بالایی در خاک دارد. بقایای این علف کش در خاک می تواند به گیاهان بعدی کشت شده در تناوب، خسارت وارد کند. به منظور ارزیابی حساسیت برخی گیاهان به بقایای شبیه سازی شده تریفلورالین در خاک آزمایشی به صورت گلدانی، بصورت فاکتوریل و در قالب طرح کاملا تصادفی در سه تکرار انجام شد. عوامل مورد بررسی در این آزمایش شامل هفت گیاه زراعی (سورگوم، ارزن، جو، گندم، یولاف وحشی، یونجه و خیار) و غلظت های مختلف تریفلورالین در خاک در هشت سطح شامل (صفر، 002/0، 004/0، 021/0، 043/0، 046/0، 086/0 و 129/0 میلی گرم ماده موثره در کیلوگرم خاک) بودند. نتایج نشان داد که بقایای تریفلورالین در خاک تاثیر معنی داری بر سبز شدن گیاهان مذکور داشت و با افزایش غلظت تریفلورالین در خاک، وزن خشک اندام های هوایی و ریشه تمام گیاهان به طور کاملا معنی داری کاهش پیدا کرد. با توجه به نتایج آزمایش، گیاه یونجه با داشتن بالاترین ED50 (0/164 میلی گرم ماده موثره در کیلوگرم خاک) زیست توده اندام های هوایی به عنوان مقاوم ترین گیاه و سورگوم با کمترین مقدار ED50 (0/048 میلی گرم ماده موثره در کیلوگرم خاک) زیست توده اندام های هوایی به عنوان حساس ترین گیاه به بقایای تریفلورالین شناخته شدند. سایر گیاهان زراعی بر اساس شاخص مذکور از نظر حساسیت به بقایای تریفلورالین در خاک به صورت یونجه< خیار< گندم< یولاف< جو ارزن سورگوم طبقه بندی شدند.
    کلیدواژگان: ارزن، جو، خیار، زیست سنجی، سورگوم، گندم، یونجه، یولاف
  • محمد جواد گل محمدی، حمید رضا محمددوست چمن آباد *، بیژن یعقوبی، مصطفی اویسی صفحات 69-84
    شناسایی علف های هرز مزارع برنج به عنوان اساسی ترین اقدام در مدیریت علف های هرز محسوب می شود. با آگاهی از فلور علف های هرز خاص در یک منطقه می توان در مورد روش های مدیریت آن ها برنامه ریزی کرد و تصمیم گرفت که می تواند باعث جلوگیری از تکرار اشتباهات برای کنترل علف های هرز در اثر عدم وجود اطلاعات کافی از علف های هرز هر منطقه باشد. به منظور شناسایی تکمیلی، پراکنش و تعیین غالبیت گونه های مختلف علف های هرز مزارع برنج در طول دوره رشد برنج، مطالعه ای سه ساله (1393 تا 1395) در 481 مزرعه از 16 شهرستان استان گیلان انجام شد. نمونه برداری بصورت تصادفی با روش سیستماتیک و مطابق الگوی W با استفاده از کوادرات 5/. در 5/. متر انجام شد. علف های هرز در هر مزرعه شناسایی و تراکم، درصد فراوانی، یکنواختی و شاخص وفور آن ها به تفکیک جنس و گونه تعیین شد. بر اساس شاخص غالبیت علف هرز، سوروف (Echinochloa crussgalli) در شهرستان های آستانه اشرفیه، املش، انزلی، رشت، رودسر، سیاهکل، فومن، لاهیجان و لنگرود بالاترین شاخص را در بین 66 گونه شناسایی شده داشت. قاشق واش (Alisma plantago-aquatica) در شهرستان های آستارا و رضوانشهر بیشترین شاخص غالبیت و فراوانی را دارد. بندواش آبزی (Paspalum distichum) از گونه های غالب در شهرستان های شفت، تالش و ماسال بود که بیشترین شاخص غالبیت را به خود اختصاص داد. اویارسلام زرد (Cyperus esculentus) در شهرستان صومعه سرا بیشترین شاخص غالبیت را دارد. شاخص شانون- وینر و سیمپسون در شهرستان تالش به ترتیب با 85/2 و 916/0 دارای بالاترین مقدار و در شهرستان رودبار به ترتیب با 97/1 و 749/0 دارای کمترین مقدار بود. در کل مزارع استان گیلان و در بین باریک برگان بالاترین یکنواختی و غالبیت برای سوروف به ترتیب با 7/34 درصد و 1/132، در جگن ها، اویارسلام زرد دارای بالاترین یکنواختی و غالبیت به ترتیب با 8/22 درصد و 8/88 و در پهن برگان، گل آردی به ترتیب 5/14 درصد و 25/66 فراوانی و غالبیت را نشان داد. نتایج نشان داد که در منطقه ای با غنای گونه ای پایین ولی تراکم بالا به دلیل استفاده از برخی روش های مدیریتی خاص، برخی علف های هرز غالب می شوند. بدین منظور کشاورزان برنجکار می بایستی در روش های مدیریتی علف های هرز تغییراتی را ایجاد کنند. در مجموع، نتایج این تحقیق نشان داد که مدیریت علف های هرز برنج استان در وضعیت مطلوبی قرار ندارند.
    کلیدواژگان: تنوع گونه ای، شانون- وینر، علف هرز، غالبیت
  • محمدحسن هادیزاده*، سید حسین حسینی کیا، سید حسین ترابی، کمال حاج محمدنیا قالیباف صفحات 85-97
    به منظور بررسی تاثیر باقی‏مانده ی چند علف‏کش سولفونیل اوره مورد استفاده در کشت گندم (Triticum aestivum L.) بر پنبه (Gossypium hirsutum L.)، آزمایشی در دو بخش مزرعه و گلخانه در قالب طرح پایه بلوک‏های کامل تصادفی با شش تیمار و چهار تکرار در شهرستان سرخس طی سال زراعی 93-1392 اجرا شد. تیمارها شامل پنج علف‏کش سولفوسولفورون (6/26 گرم در هکتارآپیروس 75%)، مزوسولفورون+یدوسولفورون+مفن پایر (5/1 لیتر در هکتار آتلانتیس 1/2%)، تریاسولفورون+دایکمبا (165 گرم در هکتار لینتور 70%)، تریاسولفورون+تربوترین (250 گرم در هکتار لوگران اکسترا 64%) و متسولفورون+سولفوسولفورون (40 گرم در هکتار توتال 80%) بودند که در مرحله رشد پنج برگی گندم به میزان توصیه شده مصرف شدند. یک تیمار شاهد بدون علف‏کش (وجین دستی علف های هرز) نیز در نظر گرفته شد. آزمون زیست سنجی باقی مانده علف کش در گلخانه با تهیه نمونه خاک از تیمارهای مذکور بلافاصله پس از برداشت گندم و کشت گلدانی گیاهان پنبه، ذرت، جو و کلزا اجرا شد. نتایج آزمایش مزرعه ای نشان داد که بقایای علف‏کش‏های توتال، آپیروس و آتلانتیس به علت وجود علف‏کش‏های پایدار مت سولفورون متیل، سولفوسولفورون و مزوسولفورون در ترکیب خود، باعث مسمومیت پنبه در ابتدای رویش به صورت توقف در رشد بوته‏ها و کاهش وزن خشک اندام هوایی شدند. ریشه پنبه در مزرعه فقط تحت تاثیر باقی‏مانده علف کش توتال قرار گرفت. علایم ظاهری خسارت از جانب هیچ تیماری در پنبه پایدار نبود، به طوری که توقف در رشد پنبه به مرور جبران شد و در نهایت تعداد غوزه و عملکرد محصول تحت تاثیر معنی دار باقی‏مانده علف‏کش‏ها قرار نگرفت. بر اساس نتایج آزمایش گلخانه ای، باقی‏مانده علف کش های توتال، آتلانتیس و آپیروس وزن خشک اندام هوایی پنبه و علف کش های توتال و آپیروس موجب کاهش معنی دار وزن خشک ریشه نسبت به شاهد شدند. میزان مسمویت گیاهان در آزمایش گلخانه برای کلزا بیشترین و برای ذرت کمترین مقدار بود. میزان اثر باقی‏مانده علف‏کش‏ها بر اساس میانگین صفات گیاهان آزمون برای علف کش لینتور کمترین و برای علف کش توتال بیشترین بود.
    کلیدواژگان: جو، زیست سنجی، ذرت، علایم خسارت چشمی، کشت دوم، کلزا
  • سمیرا ابوعلی، سهراب محمودی، حسین حمامی * صفحات 99-110
    بهینه سازی مصرف علف کش ها به وسیله کاربرد مواد افزودنی یکی از رهیافت های نوین برای کاهش عوارض زیست محیطی ناشی از کاربرد علف کش ها است. به منظور ارزیابی تاثیر مواد افزودنی در بهینه سازی کارایی علف کش های بنتازون+اسیفلورفن و ایمازتاپیر در کنترل سلمه تره، دو آزمایش گلخانه ای دز پاسخ مجزا در سال 1395 در گلخانه تحقیقاتی دانشکده کشاورزی بیرجند، به صورت فاکتوریل در قالب طرح کاملا تصادفی با چهار تکرار انجام شد. تیمارها در هر آزمایش شامل غلظت های علف کش در هفت سطح (0، 25/6، 5/12، 25، 50، 75 و 100 درصد توصیه شده) و نوع ماده افزودنی در سه سطح (روغن منداب، سیتوگیت و بدون روغن) بود. نتایج آزمایش نشان داد که کاربرد مواد افزودنی بخصوص روغن گیاهی منداب موجب افزایش کارایی علف کش های بنتازون+اسیفلورفن و ایمازتاپیر در کنترل سلمه تره شد. روغن منداب و سیتوگیت باعث افزایش کارایی علف کش بنتازون+اسیفلورفن در کاهش زیست توده تولیدی اندام های هوایی سلمه تره به ترتیب به میزان 29/1، 28/1 برابر و علف کش ایمازتاپیر 13/2 و 30/1 برابر شد. در حالی که این مقادیر برای کاهش زیست توده ریشه سلمه تره به ترتیب 79/2، 98/1، 35/2 و 66/1 برابر بود. با توجه به واکنش شدیدتر ریشه به تیمارهای اعمال شده، نتایج نشان داد که ریشه سلمه تره حساسیت بیشتری به کاربرد مواد افزودنی و علف کش های بنتازون+اسیفلورفن و ایمازتاپیر در مقایسه با اندام های هوایی داشت. بطور کلی نتایج این مطالعه نشان داد که کاربرد روغن منداب و سیتوگیت باعث افزایش کارایی کنترل سلمه تره بوسیله بنتازون+اسیفلورفن و ایمازتاپیر می شود.
    کلیدواژگان: پهن برگ، توانایی نسبی، دز موثر، گلخانه، مویان
  • محمد لطفی اصل گیگلو، مصطفی اویسی *، حمید رحیمیان مشهدی، بهناز پورمراد کلیبر، محمدحسین نعیمی صفحات 111-122
    به منظور بررسی اثر دما و نور بر سرعت و درصد نهایی جوانه زنی بذر علف هرز چوچاق (Eryngium caeruleum L.) آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی و آزمایشگاه دانشکده کشاورزی و منابع طبیعی دانشگاه تهران انجام شد. فاکتورهای آزمایشی شامل هفت سطح دمایی آزمون جوانه زنی (5، 10، 15، 20، 25، 30 و 35 درجه ی سانتی گراد)، شرایط نوری در زمان آزمون جوانه زنی (نور و عدم وجود نور) و دوره های دفن در در عمق 5 سانتی متری خاک (30، 60، 90، 120، 150 و 180 روز) بودند. نتایج نشان داد سرعت جوانه زنی تحت تاثیر دما و شرایط نوری قرار گرفت. سرعت جوانه زنی با افزایش دما تا 20 درجه سانتی گراد، افزایش و در دماهای بالاتر از 20 درجه سانتی گراد کاهش یافت. در طول زمان دفن پارامترهای دمائی دمای پایه (Tb)، دمای بهینه (To) و دمای سقف (Tc) تحت تاثیر زمان دفن و شرایط نوری در زمان آزمون جوانه زنی قرار داشتند. به طور کلی با افزایش طول دوره دفن، دمای پایه و دمای بهینه جوانه زنی کاهش و دمای سقف افزایش یافت. با افزایش مدت زمان دفن بذر، پارامترهای حداکثر سرعت جوانه زنی (Gmax) و سطح بیداری بذر (ai)، صرف نظر از وجود و یا عدم وجود نور در زمان آزمون جوانه زنی، به صورت خطی افزایش یافتند. نتایج بدست آمده از این تحقیق به تکمیل اطلاعات موجود در مورد زیست شناسی و عوامل موثر بر جوانه زنی بذر گیاه چوچاق و در نتیجه پیش بینی دامنه سازگاری و پراکندگی این گیاه در زیستگاه ها کمک می کند. از این اطلاعات می توان به عنوان ابزار تصمیم گیری مدیریتی این علف هرز استفاده کرد.
    کلیدواژگان: پارامترهای دمایی جوانه زنی، سرعت جوانه زنی، شاخص سطح بیداری، شرایط نوری
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  • Fateme Zarandi *, Farhad Shokouhifar, Bahram Sharifnabi, Badraldin Ebrahim Sayed Tabatabaei, Ziaaldin Banihashemi Pages 1-8
    Introduction
    Phytopathogenic fungi exposes various proteins to overcome plant defense systems. Production of saponins likes α-Tomatine is one of the tomato preformed defenses barriers which should be detoxicated by the pathogens. It has been revealed before which most of Fusarium species and forma specials could produce tomatinase, a glycosyl hydrolases protein, to de-glycosylate α-Tomatine. Fusarium oxysporium f. sp. melonis (FOM) wildly attached melon cultivars and at the time of this investigation, there was only one report underlining the existence of the gene sequence of tomatinase in the genome of FOM using southern blotting experiment. This study was carried out to track the whole tomatinase gene sequence in the FOM genomic sequence and investigate the probability genetic variation of the gene in the nucleotide and protein sequences.
    Materials and Methods
    Fusarium oxysporium f. sp. melonis (Fom) race1 have been previously reported in Khorasan, Iran. It was cultured in liquid medium and the mycelia were used for the genomic DNA isolation. Primers were designed based on conserved sequence in upstream and downstream of FoTom1 sequence (AJ012668). PCR was carried out and amplified segments were bi-directional sequenced. The results were then analyzed by Vector NTi software. The sequencing result was aligned with FoTom1 sequence as Refseq and the single nucleotide variations were detected by CLC work bench software. The effects of the mutations on the protein structure were predicted by CLC work bench software.
    Results and Discussion
    Electrophoresis pattern of PCR products showed a single band of the expected size in the strain FomR1 that was at the same size of the band amplified from FoL genome. The designed primers based on the FoTom1 sequence amplified a specific segment in the Fom genome. Alignment the sequencing results with the Fo-Tom1 from Fusarium oxysporium f. sp. lycopercisi (Fol) in nucleotide level revealed 14 mutations which seven of them were appeared in the protein sequence. Three mutations occurred in the functional domain of the protein. At the position 145, an acidic amino acid with a negative charge was substituted by a polar amino acid. Replacements at positions 218 and 236 were the same in terms of polarity and at position 218; both amino acids have a positive charge.
    There were no introns in the coding sequence of FomTom R1 region as same as FoTom1. Pairwise alignment results showed some an-synonyms mutations between two sequences that made some changes in the secondary structure of the translated protein from FomTomR1. The first an-synonym mutation, SNP15 (E→G), inside the signal peptide, converts the alpha helix to a new beta sheet. SNP34 (K→N) and SNP35 (S→N) mutations shortened the alpha helix. The other mutations happened out of the alpha helixes and beta sheets. To predict the effects of the mutations on the FomTomR1function, in-silico analyses were carried out. The results revealed that three mutations occurred in the functional domains of tomatinase in Fom. The mutations in the hydrolysis domain may affect the structure of FomTomR1and can be effective in the protein. The presence of different active saponins components in Melon may be an evolutionary reason for some variation in sequence and structure of the FomTomR1 protein in Fom. To prove the differences in the tomatinase function, the interaction of proteins with various types of melon saponins components should be investigated at the future studies.
    Conclusion
    The results showed the tracked sequence could be homolog of the Tomatinse gene in the Fom genome. We named it Fom-TomR1 and the sequenced was submitted in the Genbank with accession number MF178403. For the future study, the gene influences should be investigated in the pathogenesis of FOM on melon cultivars and it could be considered as a general screening index using heterologous expression of the gene.
    Keywords: Fusarium wilts disease, Gene detection, Secondary structure prediction, Single nucleotide polymorphism
  • Fereshteh Esmaeilzadeh, Seyed Mehdi Bani Hashemian *, Ahmad Rouhibakhsh, Syrous Aghajanzadeh Pages 9-16
    Introduction
    Citrus tristeza virus (CTV), the causal agent of the most important viral disease of citrus, is transmitted by infected reproductive materials and several aphid species. Tristeza has been reported from the north and south of Iran and Aphis gossypii has been known as the vector of Tristeza. Detection of the virus in the vectors has been before carried out based on biology, serology and electron microscopy. Access to rapid and sensitive molecular techniques for epidemiological studies is the aim of the study. Reverse transcription polymerase chain (RT-PCR) and RT-nested PCR techniques were applied in the present study.
    Materials and Methods
    The SD4-infected Mexican lime (Citrus aurantifolia) seedlings acquired from the virus collection with origin of declining trees of Sari region were used as donor host for virus transmission assays. Pure colony of A. gossypii after rearing on cucumber (Cucumis sativus) was placed on the infected seedlings. 20 seedlings were considered for biological indexing. 20 aphids were placed carefully on healthy Mexican lime seedlings by brush. The acquisition and transmission feeding time of virus were 48 hours and 20 aphids were considered for each test plant. The seedlings were transferred to the conditioned greenhouse (23/16°C, day/night). Indirect virus detection was carried out by monitoring of symptoms, direct tissue blot immuonoassay with Biorba antiserum and two step RT-PCR with RNA extracted from indicator plants using SDS-Potassium acetate method and T36CPF/T36CPR primers. In direct detection virus of aphid, RNA extracted by Trizol method and one step RT-PCR reaction using AMV Reverse Transcriptase enzyme by T36CPF/T36CPR primers were used. The final product of this reaction was introduced in the nested-PCR using T36CPF/P25R primers. RT-nested-PCR assay was applied also with PexF/PexR primers in the first stage and PinF/PinR in the second stage.
    Results and Discussion
    Indirect virus detection in melon aphid was carried out by survey of vein clearing and vein corking symptoms in the receptor indicator plants. A total of 4 of 20 Mexican lime seedlings showed the symptoms during 3 months after aphid transmission assay. The presence of virus in these seedlings was confirmed by direct tissue blot immunoassay and RT-PCR techniques. Also a product of about 672 bp was amplified using specific primers of coat protein gene. Direct virus detection with one-step RT-PCR and RNA extracted from aphids by Trizol method using T36CPF/T36CPR primers resulted 672 bp weak bands. By performing the second stage of PCR using T36CPF/P25R primers, 362 bp specific bands were obtained. On the other hand, RT-nested PCR with PinF/PinR and PexF/PexR primers was not able to detect the virus in the infected aphids due to false positive reactions. The purpose of this study was to evaluate the effectiveness of different methods in selecting an appropriate method for detection of virus in melon aphid, the most effective vector of CTV in Iran. The detection of virus-associated targets in vectors that are capable of transmitting viruses is crucial for both the studies of viral replication and the optimization of control strategies. Biological indexing is the earliest test of detection of virus in aphids, which has the advantages and disadvantages, including the objective measurement of biological activities such as ability to transmit and reproduce based on production of symptoms, the long time required, and the specific greenhouse conditions. Although RT-PCR method has been used to detect a number of plant viruses in vectors, the detection of virus by this method is possible if extraction efficiency of RNA is increased by use of materials such as Gene Releaser and Trizol. Nevertheless, more sensitive methods are required for detection of semi-persistently and non-persistenly transmitted viruses. Detection of CTV by nested RT-PCR was directly related to appropriate primers and efficient extraction procedure.
    Conclusion
    According to this study, RNA extraction using Trizol method is the most appropriate method for extracting nucleic acid from aphids, so it has been shown that detection of CTV by nested RT-PCR technique was directly related to the used extraction procedure. In this research, detection of Citrus tristeza virus in melon aphid for the first time in Iran was performed using RT-PCR and RT-nested-PCR molecular methods. The results showed that RT-nested-PCR based on the efficient extraction method and the selection of appropriate primers is a reliable technical for detection Tristeza virus in its aphid vector, A. gossypii.
    Keywords: Aphid vector, Biological indexing, Direct detection, Tristeza virus
  • Morteza Golmohammadi * Pages 17-21
    Introduction
    HLB (Huanglongbing ex greening) caused by three species of bacterium Candidatus Liberibacter asiaticus, Ca. L. africanus and Ca. L. americanus, is the most important citrus disease over the globe. The causal agent is transmitted by two psyllids Diaphorina citri and Trioza erytreae and infected bud woods. The causal agent of HLB disease was identified as a phloem-restricted, Gram-negative bacterium belonging to a new genus in the α-Proteobacteria subdivision. In Asia, the pathogen of HLB was categorized as the Candidatus Liberibacter asiaticus transmitted by the Asian citrus psyllid (Diaphorina citri). This was also reported in the south of Iran over 2000. Diagnosis of HLB disease can be difficult under field conditions when relying on visual surveys. This is due to its low concentration in its citrus hosts and the nonspecific nature of HLB symptoms, similarity of its symptoms to micronutrient deficiency such as zinc, magnesium, and iron and virus-like disease symptoms such as stubborn caused by Spiroplasma citri. Therefore, distinguishing causal agents of similar symptoms such as nutritional or stress related symptoms from HLB disease needs a robust procedure. Many detection methods have been used to detect Candidatus Liberibacter spp. including biological indexing (grafting and vector), electronic microscopy (EM), DNA probe specific to the bacterium, enzyme- linked Immunosorbent assay (ELISA). However, TEM methods are less practical, because ultra-thin sectioning is tedious and requires expensive equipment. Transmission tests are of limited value due to the latency and the long incubation period in insect and plant. Development of conventional polymerase chain reaction (PCR) test has great advantages of analyzing the bacterium at genetic level. The objective of this study was the detection of HLB in symptomatic citrus plants based on conventional polymerase chain reaction assay (PCR) in the south of Iran and the comparison of Iranian strains with other strains on the globe.
    Materials and Methods
    In order to detect, identify and characterize the diseases, leaf and fruit samples were collected from some suspected sites situated in the southern Kerman. Samples were stored in plastic bags and transferred into the laboratory and conserved at low temperature (60C) before DNA extraction. Total DNA was extracted from symptomatic samples on the basis of the method/protocol of Murray and Thompson (1980) with minor modifications. Briefly, 5 to 10 symptomatic leaves were washed with sterile water and dried on paper. The leaf midrib tissue derived from field plants was cut out by sterile scalpel and CTAB buffer added with addition of B-mercaptoethanol. The extract was transferred to a new tube and incubated at 65 0c for 15min. The other steps were conducted according to the original protocol. Existence of pathogen in samples was confirmed using PCR with primers A2 / J5 and OI1 / OI2c.
    Results and Discussion
    The PCR products were analyzed by gel electrophoresis using a 1% agarose in TBE buffer (Tris base, boric acid and 0.5M EDTA [pH 8.0]) and stained with ethidium bromide. Gel was visualized and analyzed by the GEL documentation.12 of 48 samples amplified with primers above and the disease was confirmed. By sequencing of PCR products with length of 1077 bp and comparison with the strains positive control, also production two fragments of 640 bp and 520 bp resulting from the digestion with XbaI PCR products, the agent of disease was found to be Candidatus Liberibacter asiaticus. The agent showed 100% homology with standard HLB Asiatic type. BLAST analysis showed that the nucleotide sequences obtained for the ribosomal protein (GenBank Accessions No. GN 049632) had 100% identity with sequences of ‘Ca. L. asiaticus’ from China (DQ431997), Taiwan (AB555707), Indonesia (AB480102), Florida (CP001677), and Brazil (AY91933). The Asian vector of HLB, Diaphorina citri was reported in 2000, therefore, the diseases might be distributed in other areas in the southern Iran. Thus, detection of HLB disease in young citrus plants is important to prevent a widespread outbreak of this disease. The results also showed that Iranian strain belongs to Asian type of Liberibacter and nominated Candidatus Liberibacter asiaticus. In the southern Iran, Diaphorina citri with high ability to spread the Candidatus Liberibacter asiaticus is found in most of citrus cultivating areas which implies a high risk of rapid dissemination. Therefore, the survey of the disease by an accurate and sensitive method is recommended for the disease detection in new areas and eradication of infected trees.
    Keywords: Asiatic type, Detection, Candidatus Liberibacter asiaticus, PCR
  • MOHANAD ALGABRI, Mohsen Mehrvar *, Mohammad Zaki Aghl Pages 23-26
    Introduction
    Wisteria vein mosaic virus (WVMV) is a member of the Potyvirus genus (Potyviridae) with flexuous filamentous particles. The disease was first reported by Brierley & Lorentz (1957) in the USA from W. floribunda. They cited reports of similar cases dating back to the 1940s and suspected that a virus was responsible for the disease. Afterward the virus has been reported in Wisteria spp. in Australia, New Zealand, China, Germany, Czech Republic, Italy and in the Netherland. In comparison to the majority of potyviruses, WVMV has a very narrow host range, naturally infecting only Wisteria spp. (W. sinensis, W. floribunda, and W. venusta). This virus can be introduced into the landscapes on new plants that were infected during their production. Other wisteria can become infected by mechanical inoculation if infected sap is moved on cutting tools or by aphids during feeding from sap of these plants. In terms of symptoms induction, the virus can cause systemic, local chlorotic (sometimes necrotic) lesions or mottling and mosaic on the leaves of wisteria spp. plants and other experimental hosts of Chenopodium spp., Nicotiana megalosiphon and several legumes. The virus is serologically related to Bean common mosaic virus (BCMV), Bean yellow mosaic virus (BYMV), Clover yellow vein virus (ClYVV) and Watermelon mosaic virus (WMV). WVMV is transmitted by aphids, grafting or mechanical means with no significant impact on ornamental host plant except inducing an unfavorable leaf appearance in the landscape.
    Materials and Methods
    In August 2017, a plant of Wisteria sinensis in the campus of Ferdowsi University of Mashhad in Iran was observed to have chlorotic, mottling and mosaics on some leaves, which resembled the symptoms caused by wisteria mosaic disease. RNA was extracted from the symptomatic plant with an RNeasy Plant Mini Kit (Qiagen, Germany) and tested by RT-PCR using potyvirus degenerate primers CIF/R. Amplicons of the expected size, 680 bp were obtained. The PCR product was cloned and then sequenced. The partial sequence of Nib gene was also amplified (350 bp) by degenerate primer for potyvirus Nib gene and the obtained fragment were cloned and then sequenced.
    Results and Discussion
    A BLASTn search in the GenBank showed 90.64% nucleotide sequence identity with WVMV Chinese isolate (AY656816) followed by Watermelon mosaic virus (80.67%) and Soybean mosaic virus (80.46%). The least identity was with an isolate of Lettuce mosaic virus (56.34%). It seems that the Chinese and Iranian isolates of this virus are closer to each other but due to lack of nucleotide sequence from other part of the world in CI and Nib genes it is hard to conclude that Iranian isolate is just close to Chinese isolate and it should be considered that may other isolates exist which are closer to Iranian WVMV isolate than Chinese isolate.
    Conclusion
    From this research, it can be concluded that this virus is present in wisteria spp. plant in Khorasan Razavi province of Iran. In terms of sequence similarity based on partial nt sequence of CI gene (680 nt), it is most similar to a Chinese isolate of WVMV (90.64 %) followed by WMV (80.67 %) and SMV (80.46 %) in nt level and within BCMV subgroup of potyviruses. It seems likely that the disease is spread primarily through vegetative propagation rather than by aphid or mechanical transmission. Although the disease does not markedly reduce the vigour of infected plants, the foliage of such plants is chlorotic and mottled, rendering them unsaleable or can cause the ornamental plants as unfavorable host.
    Keywords: CI gene, Khorasan Razavi, Phylogenetic analysis, RT-PCR, Wisteria vein mosaic virus
  • Sedighe Ashtari * Pages 27-34
    Introduction
    Trichogramma wasp is one of the most successful parasitic species in the world and the widespread use of these wasps has taken control of many pests in more than 30 countries. Approximately 32 million hectares of agricultural land and forests have been covered by the Trichogramma every year. This parasitoid is reared on Sitotroga cerealella (Lep.: Gelechiidae) and Ephestia kuehniella (Lep.: Pyralidae). The superiority of these bees is their ability to destroy the egg pest before its damage to the host plant. Nonselective insecticides can reduce the potential of biological control agents. In order to determine the most suitable insecticide for effective pest control of Trichogramma wasps, the present study evaluated the persistence toxicity of spinosad, indoxacarb and imidacloprid after exposing of T. brassicae and T. evanescens, the egg parasitoids of tomato leaf miner, according to IOBC procedure.
    Materials and Methods
    The experiments were carried out in the Laboratory of Plant Protection at Agricultural and Natural Resources Research and Education Center of Markazi Province, Arak, Iran. The egg parasitoids T. brassicae and T. evanescens (Hymenoptera: Trichogrammatidae) were provided from Biological Control Department of Plant Protection Research Institute (Tehran, Iran). The parasitoids were reared on the Angoumois grain moth, Sitotroga cerealella (Lepidoptera: Gelechiidae) at the laboratory under the controlled conditions of 25±1°C, 65±10% RH and photoperiod of 16:8 h (L: D). Insecticides: The recommended doses (RD) of the insecticides of Spinosad (SC 22.8% Spintor, DowAgroscience Co.), Imidacloprid (SC35% Confidor, Bayer) and Indoxacarb (SC15% Avant, Aria Shimi) were tested.
    Persistent tests: The insecticides were applied at RD on tomato plants by a hand sprayer to the point of run off. Plants were maintained under a transparent polyethylene rain cover in the field. Leaves of the treated tomato plant were sampled and transferred to the laboratory at different time intervals of 3, 5, 16 and 31 days after insecticide application. These intervals were proposed by the IOBC/WPRS Working Group. The samples were placed in ventilated plastic Petri dishes for exposure to the adult parasitoids. The experiment was repeated six times on 30 adult individuals of each species. Assessment of mortality was made on the basis of 24 h post exposure time. Persistence rate of wasps against each insecticide was evaluated according to IOBC/WPRS Working Group. The categories under laboratory conditions include: A, short lived (<5days); B, slightly persistent (5-15days); C, moderately persistent (16-30days); D, Persistent (>30 days).
    Results and Discussion
    Persistence tests for 30% mortality at each period of time revealed that imidacloprid with less than five days persistence classified as short lived insecticides (class A) for T. brassicae and T. evanescens wasps, indoxacarb with more than five days and less than 16 days effect was slightly persistent (class B) and spinosad which persisted more than 16 days but less than 30 days was moderately persistent for the parasitoid T. brassicae and T. evanescens (class C) (Table 1, 2). This research clearly showed that imidacloprid which persisted less than five days at field conditions were compatible with both egg parasitoids, T. brassicae and T. evanescence as a part of integrated management program of pests. This study also revealed that both parasitoids responded at the same level of susceptibility after exposure to the insecticide. There is no evidence for effect of imidacloprid on Trichogramma parasitoids, however our finding was the same as the results of Fernández et al. (2017) who reported imidacloprid was safe for predatory mite Amblyseius swirskii adults. Some researchers also emphasized on computability of this insecticide with a large number of natural enemies, including the predatory mites Amblyseius cucumeris and Phytoseiulus persimilis. The insecticide was compatible with all stages of phytoseiid mites, reported by Lefebvre et al. (2011) and Beers and Schmidt (2014) in Galendromus occidentalis. Garzon et al., (2015) also reported this insecticide was nontoxic to last instar larvae and adults of Chrysoperla carnea and Adalia bipunctata so they emphasized that it is a good candidate to be incorporated into IPM programs. On the contrary, Doker et al., (2015) reported a significant reduction in oviposition of Iphiseius degenerans after exposure to imidacloprid.
    Conclusion
    This research focused on the impact of insecticide exposure on Trichogramma species in Markazi Province. Pesticides that control pests without severe side effects on substantial natural enemies are always a necessity for integrated control programs. The application of the short-lived insecticides can allow a rapid recolonization of the parasitoids. We found imidacloprid is non-harmful for both T. brassicae and T. evanescence wasps. By contrast, spinosad and indoxacarb should be used with care as a part of IPM procedure.
    Keywords: Parasitoides, Persistency of insecticide, Semi field conditions
  • Ladan Poursartip *, Korosh Saadatvafa, Pejman Rezayati Charani Pages 35-43
    Introduction
    One of the most important species of termites in the southern provinces of Iran is Microcerotermes diversus Silvestri, which is considered as subterranean termite and has the ability to attack the trees and the construction of timber. Due to the fact that Lignocellulosic material can be eaten easily by termite, this can cause great damage to buildings, so identifying resistant wooden species can help us to select suitable materials in areas where termite infestation is high. The aim of this study was to evaluate the tendency of M. diversus termite for different woods by using selective and non-selective nutritional tests in laboratory conditions.
    Materials and Methods
    For the collection of termites, beech wood with dimensions of 2.5 × 4 × 20 cm was buried for two months inside the soil in an abandoned palm farm, 20 km from the city of Behbahan. After that, the woods were removed from the soil and transferred to the laboratory. Then, parameters such as percentage of extract material, specific gravity, lignin and cellulose content were calculated for each wooden sample. Determination of cellulose and lignin content of woods was carried out according to the T-264cm-88 and T-222cm-88, TAPPI standard, respectively. The measurement of extractive materials was carried out in accordance with the TAPPI Regulation No: T 204om-88ISO-3131 standard to measure dry specific gravity.
    The data was analyzed by Tukey's test using SPSS software version 17, and the significance test was performed at 95% level using Pearson correlation test.
    Results
    According to the results, the percentage of eucalyptus extractives is higher than other species and all three species have a significant difference at 95% level. All three species have a significant difference at 95% level in amount of lignin and the highest and the lowest one was related to cypress and the beech species, respectively.
    Also, the results showed that there is no significant difference between the three species in terms of cellulose content.
    The highest level of dry specific gravity is also found in beech and the least of that belongs to the cypress. All three species have a significant difference at 95% level. The results of non-selective test of wooden samples showed that the cypress samples had the least weight loss and the highest weight loss was observed in the beech samples. Eucalyptus specimens were interstitial and had a significant difference with samples cypress and beech. Comparison of weight loss percentage in wooden samples illustrated that the lowest and the highest percentage of weight loss belonged to cypress species and beech, respectively. However, there is no significant difference between eucalyptus species and two other species.
    Conclusion
    Selective and non-selective feeding of termites revealed that in both tests, there was a significant difference between the weight loss of cypress and beech, and the eucalyptus samples did not have a significant difference with the other two samples. Increasing the lignin decreased wood utilization for the termite. There is a significant difference between lignin content in these two species, the highest amount of lignin was obtained in cypress and the least one belongs to beech. Lignin which is composed of phenyl propane units, is known as malicious factors for pests due to the presence of aromatic groups in its structure. . The presence of extractives in eucalyptus should not be ignored in resistance to termites too. There are a wide variety of extractive materials in wooden species that affect wood properties such as the natural durability. The amount of extractives along with lignin can prevent the pest infestation. In the present study, the specific gravity among the three species was significant, and the highest and the lowest one belongs to beech and cypress, respectively. According to the results of other researchers, it was expected that the higher specific gravity would reduce the desirability for termites to consume wood, while our study demonstrated the effect of lignin and extractives are more meaningful in terms of termite deterrence.
    Keywords: Extractive materials, Lignin, Lignocellulose materials, Specific gravity, Termite feeding
  • Sanaz Farkhondeh, Leia Alimoradi *, K. Kalarestaghi Pages 45-55
    Introduction
    Nowadays, concerns about side-effects of herbicides on human health and environment leading to increase the cost of new herbicide registration or reduce the old herbicide efficacy. Surfactants could increase the efficacy of post-emergence herbicides, due to reduction of herbicide solution surface tension. Surfactants may improve the herbicide effects and hence, reduce the amount of used herbicide to achieve the same results and this decreases the cost of herbicide application and the environmental effects. Surfactants are used in order to optimize the herbicide leaf uptake. They prevent the herbicide crystallization on leaf surface, herbicide drift and light composition. They improve the water quality for herbicide application, reduce the contact angle of herbicide droplet and also they spread and stick the herbicide droplet on leaf surface and facilitate the herbicide penetration into leaf cuticle. Some of surfactants are herbicide modifier, extender, and sometimes are safener or synergist.
    This study was conducted in order to determine whether the efficacy of mesosulfuron-methyl+sulfosulfuron (TotalR) herbicide on Avena ludoviciana control, could be improved by adding mineral oil surfactants.
    Materials and Methods
    In order to study the efficacy of different mineral oil surfactants in mixture with TotalR herbicide on Avena ludoviciana control, an experiment was conducted at research greenhouse, Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012. The study was a factorial experiment based on Completely Randomized Block (CRB) design, with four replications. The treatments were different TotalR herbicide concentrations (0, 5.625, 11.25, 22.50, 33.75, 45 gr a.i. /hectare) as factor A and factor B was different surfactants (Adigor, Propel, Volk, Citogate, Frigate and D-actil at 1% and 2% (v/v)) and distilled water as control. The seeds from Avena ludoviciana populations were collected from cropping fields of Mashhad Agricultural and Natural Resources Research Center, and were stored at dark incubator 4±1oC, during 72 hours. Then, the seeds were dehulled and placed in petri dishes and incubated for 48 hours at 4-5oC in darkness for dormancy breaking. The seeds were sown in potting tray (3*3*5 cm) filled with moistened peat. The trays were transported to germinator with 16/8 hour day/night and 20/10oC temperature. One week after sowing, when the seedlings were at one leaf stage, ten seedlings were transplanted in each plastic pots, that filled by mixture of soil, humus and silt (1:1:1 v/v/v). The pots were placed in greenhouse, 27±5/18±5oC, day/night. The pots were irrigated 2 days intervals. After 1 week the plants were thinned to 5 seedlings in each pot. The treatments were applied at 5 leaves stage by using an overhead trolled sprayer (Matabi 121030 SuperAgro 20 L sprayer, equipped with an 8002 flat fan nozzle tip delivering 200 L/ha, 2 bar spray pressure). Four weeks after spraying, plant biomass in each pot was harvested and recorded as fresh weight. Then, the samples were oven-dried at 75oC for 48 hours to measure the dry matter. The surface tension was measured by capillarity method. Logistic dose-response curves was used to describe the plant response (Fresh weight and dry matter of Avena ludoviciana) against the dose of herbicide alone or in mixture with surfactants at 1 and 2% concentration. Data were analyzed by SAS software, and mean comparison was done by LSD test (P<5%).
    Results and Discussion
    Results showed that, all surfactants reduced TotalR solution surface tension, significantly. Surface tension was reduced by Citogate, D-actil, Frigate, Volk, Propel, Adigor, respectively. ANOVA results also showed that different herbicide doses and surfactant type had significant effect on Avena Ludoviciana dry and fresh weight. When the logistic dose-response curve was fitted for the effect of Total® herbicide on Avena loduviciana dry matter and fresh weight, both of them showed the same trend. It was observed that addition of mineral oils to herbicide solution improved Avena ludoviciana control. ED10, ED50 and ED90 as the regression coefficients are 13.09, 17.05, 26.01 gr i.a./ha for fresh weight and 6.75, 15.87, 31.39 gr i.a./ha for dry matter, respectively. In presence of surfactants, ED10, ED50 and ED90 was reduced for Avena ludoviciana fresh weight and dry matter and this represent the surfactant effect on herbicide efficacy. Herbicide relative potential index was more than one, when surfactants were used in mix with herbicide. Addition of all surfactant increased the efficacy of herbicide in reducing avena biomass. The results also showed that, Adigor (2% concentration) improved the herbicide efficacy 4.37 and 2.24 based on fresh weight and dry matter. Generally, it is possible to rank the surfactants in order for their ability to enhance the efficacy of TotalR solution as Adigor, Propel, Volk, D-actil, Citogate and Frigate, respectively.
    Conclusion
    It is concluded that surface tension reduction ability may not be a correct index for surfactant selection. The efficacy improvement of tested herbicide by using mineral oils, may be due to solubilizing, softening, and disrupting the leaf cuticular wax by petroleum-based oils, despite the surface tension reduction of herbicide solution. This process can improve retention and diffusion of active ingredient of herbicide into cuticular wax. Consequently, more active ingredient arrives to site of action and a subsequent increases the effectiveness of herbicide.
    Proper surfactant selection is a key factor for efficacious weed management via reducing herbicide rate, which is a main research priority. This research demonstrated that when surfactants were tank mixed with tested herbicide, the herbicidal efficacy on Avena ludoviana species significantly improved.
    Keywords: Adigor, Surface tension, Surfactant
  • Majid Barzoei, E . Izadi Darbandi *, M Rashed Mohassel, M Rastgoo, M Hassanzadeh Pages 57-67
    Introduction
    Trifluralin is one of the important soil applied selective, pre-sowing or pre-emergence herbicide used to control many annual grasses and broadleaf weeds in a large variety of arable and horticultural crops. It is a generally regarded as a moderately persistence herbicide with a half-life of 1.5 to 6.5 months. Several factors determine the length of time herbicides persist and their carryover. These factors fall into three categories: soil factors, climatic conditions, and herbicide properties. Soil related factors including soil temperature, soil texture, and soil moisture and soil organic matter are the most important factors in herbicide persistence. However physicochemical of herbicide such as absorption properties are also important factor. So different herbicides may have different persistence in soil and have different effects on agroecosytems and also on subsequent rotational crops. Normally residual herbicides extend the period of weed control, and increase the efficiency of weed management efforts. However, they may persist longer than desired and injure or kill subsequent rotational crops. Most herbicide labels include crop rotation guidelines, but rotational restrictions are often not listed for many crops. Several experiments have demonstrated that trifluralin herbicide can per sist in the soil and carryover to affect succeeding crops. Some crops tolerate a particular herbicide residue and can be replanted soon after that herbicide is applied, while other crops remain sensitive to the herbicide for a longer time after application. This experiment was conducted to investigation of some plants sensitivity to soil residue of trifluralin in greenhouse conditions.
    Materials and Methods
    To evaluate the sensitivity of some plants to simulated trifluralin soil residues, an experiment was conducted based on completely randomized design as factorial layout and four replications in Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad. Treatments included seven plants (sorghum, millet, barley, wheat, oat, alfalfa and cucumber) and eight levels of concentrations of simulated trifluralin residue in soil (0, 0.002, 0.004, 0.021, 0.043, 0.046, 0.086 and 0.129 mg a.i. kg-1 soil). Trifluralin aquatic solution incorporated to soil and transported to the plastic pots with a 15-cm diameter. Plants emergence percentage was recorded and their shoot and root biomass were measured 35 days after emergence. The data were statistically analyzed using analysis of variance, and differences among mean values of treatments were compared by Duncan's test using SAS software. For determination the required dose of herbicides to reduce 50% of plants response (ED50), the dose response curves were fitted simultaneously using the following three-parameter logistic dose-response model with the lower limit equal to zero.
    Where f is the response (above ground dry weight and root dry weight), d is the upper limit, b is the curve slope, e denotes the dose required to give a response halfway between the upper and lower limits (ED50); and x is the herbicide concentration in soil. The validity of the above model and the comparisons between the parameters were made using F-test for lack-of-fit with a 5% level of significance.
    Results and Discussion
    Results showed that trifluralin residue decreased plants mergence and shoot and root biomass. By increasing the trifluralin soil residue, reduced all above mentioned parameters significantly (p≤0.01) in all plants. Plants showed different response (p≤0.01) to trifluralin soil residue. The highest and the lowest percent shoot and root dry weight to control treatment were observed in alfafa and sorghum, respectively. Based on ED50 parameter, alfafa (0.164 mg a.i. trifluralin kg-1 soil) and sorghum (0.048 mg a.i. trifluralin kg -1 soil) appeared the most tolerant and the most sensitive plants to trifluraline soil residue, respectively. The other crops sensitivity to trifluralin in soil residue followed the following order: sorghum> millet >barley> wild oat > wheat > cucumber >alfafa.
    Conclusion
    According to the results, trifluralin residue in soil can affect the growth of rotational crops specially sorghum and millet. Therefore, regarding to the distance planting of sensitive crops after trifluralin application is necessary. Based on the results, plant response to trifluralin residues in soil were different significantly. However some sensitive plants such as sorghum and millet may be used for soil residue of trifluraline in bioassay experiments.
    Keywords: Alfalfa, Barley, Bioassays, Cucumber, Millet, Sorghum, Wheat, Wild oat
  • MohammadJavad Golmohammadi, HamidReza Mohammaddoust Chamanabad *, Bijan Yaghoubi, Mostafa Oveisi Pages 69-84
    Introduction
    The culture of man and rice have historical and profound relationships. Rice (Oryza sativa L.) has an inescapable role in providing food, economy, religion and civilization in many countries of the world. Weeds are among the most important factors affecting crops such as rice. Successful weed control is essential for rice production. Grasses, broad-leaved, sedges, ferns and algae are the weeds of Guilan rice fields. Infestation of weeds in a field can be described by three characteristics of the number of available weed species, the density of each species and the distribution of species in the field. The species in a field are almost constant from year to year, but the other two factors vary greatly in response to the environment, agronomic plans and weed management practices. However, detailed information on the presence, composition, abundance, importance and ranking of weed species depends on weed management strategies with average yield of rice. The objective of this study was to investigate rice weed community richness and composition in the Guilan province, Iran during 2014 and 2016 and their relationships with management.
    Materials and Methods
    The study was conducted in Guilan province (between 36° 34' to 38° 27' latitudes and 48° 53' to 50° 34' longitudes), northern Iran, with 14044 kilometer square of area. 481 fields were selected from 10 days after transplantation to the end of panicle formation. Taking the area of each field into consideration, 0.25 m2 quadrats were done for sampling using a W-shaped sampling pattern. The weeds at each quadrat were counted and their genera and species were identified. The Frequency, field uniformity over all fields, density of the weeds in each field, the mean weed density of the visited fields, and dominance of the various species in each region were determined. The Simpson index (D) gives more importance to the common species, but the Shannon-Wiener index (H) puts greater importance on rare species. After collecting the data and making the calculations required for determining the population indices, this information created the main layer in the project, and was then designed in the format of a databank.
    Results and Discussion
    66 weed species were identified in rice fields of Guilan province, which belonged to 29 families. According to the dominance index of weed, Echinochloa crussgalli was the highest among 66 identified species in Astaneasharafyeh, Amlash, Anzali, Rasht, Roudsar, Siahkal, Fouman, Lahijan and Langroud. Alisma plantago-aquatica had the highest prevalence index in Rezvanshahr. Paspalum distichum was one of the dominant species in shaft, Talesh and Masal regions, having the highest dominance index. Cyperus difformis had the highest dominance index in Somesara. Bolbosoenus maritimus was one of the most important weeds in rice fields located in Roudbar with dominance index equal to 9.9. Azolla filiculoides in 11 regions of Guilan had the highest frequency among floating and submerged weeds in 16 regions. The green algae were the dominant weeds at Astaneasharafyeh and Masal. In the both of regions of Somesara and Lahijan, Lemna minor was the most abundant aquatic weeds. Najas marina is the herbaceous plant having the highest abundance among floating and submerged species in Roudbar. The Shannon-Weiner and Simpson indices were the highest in Talesh (2.85 and 11.93, respectively) and the lowest in Roudbar (1.97 and 3.99, respectively). Uniformity index in Rezvanshahr had the largest quantity equal to 0.806.
    Conclusion
    Identification of weeds is the most important action for weed management. Weed flora composition in rice fields of 16 areas at Guilan Province consisted of 66 species belonging to 29 families. Roudsar and Langaroud regions were the most dominant sites with a total of 47 weed species followed by Rasht and Lahijan (46 sp.), Astaneasharafyeh (42 sp.), Amlash (37 sp.), Talesh (36 sp.), Fouman and Siahkal (34 sp.), Roudbar (32 sp.), Rezvanshahr and Somesara (30 sp.), Masal (28 sp.), Astara (27 sp.) and Shaft and Anzali (25 sp.). Ten species, three grass (narrowleaf) species (E. crussgalli, P. distichum, and E. oryzoides), three sedge species (C. esculentus, C. serotinus, and C. difformis), four broad-leaved species (E. prostrata, S. trifolia and A. plantago-aquatica), and one fern species (A. filiculoides) were the most widespread and of the highest abundance. Frequency, density and dominance of weeds according to the rice ecosystem in different regions can be changed. Due to lack of knowledge on identification and effective weed control factors, the weeds population is growing. Therefore, assessing the management role in changing the weed communities structure of species diversity can be useful to improve weed control.
    Keywords: Dominance, Shannon-Weiner, Species diversity, Weed
  • Mohammad Hassan Hadizadeh *, Seyed Hossein Hosseinikia, Seyed Hossein Torabi, Kamal Hajmohammadnia Ghalibaf Pages 85-97
    Introduction
    Cotton as a second crop is planted at some relatively warm and dry conditions in rotation after wheat, in Iran. In this situation, herbicide residue persistence is a determining factor for cotton production. Seven sulfonylurea herbicides were registered for weed control of wheat in Iran and some of them may have adverse residue effects on growth and yield of cotton. Sulfonylurea herbicides at very low doses, inhibit synthesis of essential amino acid such as leucine, iso-leucine, and valin in the sensitive plants. Many studies demonstrated that there is dangerous residue of sulfonylurea herbicide in a soil with high pH, low moisture and organic matter level, and with the short time between herbicide application and the emergence of the following crop. For example, 135 days after application of metsulfuron, triasulfuron, and chlorosulfuron, cotton biomass was reduced by 23% to 67% in a soil with pH ranged 7.8 to 8.6 (6). In the other studies, sulfosulfuron residue caused damage to barley, lens, sorghum, and sunflower as sensitive crop after one year (16, 20). Residue of triasulfuron (at 22 gr.ha-1) one year after application made injuries to alfalfa, canola, corn, potato and sugar beet (21).
    Materials and Methods
    This study was conducted during 2013-2014 to evaluate residue effects of some sulfonylurea herbicides of wheat on cotton at Sarakhs region of Iran. The soil textural class was silty clay with EC= 5.62 dS.m-1 and pH= 8.2. The field trial was a randomized complete block design with seven treatments in four replications. The treatments consisted of five sulfonylurea herbicide treatments as follows: 1- sulfosulfuron (26.6 g.ha-1 of Apyros® 75%WG), 2- mesosulfuron + iodosulfuron + mefenpyre (1.5 L.ha-1 of Atlantis® 1.2% OD), 3- triasulfuron + dicamba (165 g.ha-1 of Lenture® 70% WG), 4- triasulfuron + terbutryn (250 g.ha-1 of Logran Extra® 64% WG) and 5- metsulfuron + sulfosulfuron (40 g.ha-1 of Total® 75% WG). All herbicides applied in 3-5 leaf stage of wheat on 23th November, 2013. Furthermore, one herbicide free treatment (all season hand weeding) was considered as the control. Immediately after wheat harvest, cotton (Gossypium hirsutum L. var. Varamin) was planted (June 2, 2014) as the second crop in wheat spaces by a direct seeding machine. Residue effects on cotton plants were measured by plant height, stem length and dry matter (DM). Rankings of visual injury based on EWRC (European Weed Research Council) were recorded at four times starting seven days after cotton emergence. Cotton was harvested on September 26, 2014 and bull number, boll yield, and fiber yield were then determined. At the same time, residual bioassay tests were done in completely randomized design with four replications in the greenhouse using cotton, corn, barley, and canola. Their shoot and root dry matters were measured three weeks after emergence. Analysis of variance and mean comparisons (LSD 5%) was accomplished by SAS® (ver. 9.2) software.
    Results and Discussion
    The results showed herbicide residue from and sulfosulfuron and metsulfuron+ sulfosulfuron significantly reduced cotton plant height and dry matter in the field at the first time of sampling (30 days after emergence). However, the differences in plant heights were not significant at the second and third sampling time owing to growth compensation after crop fertilization. It seems that metsulfuron is more important than sulfosulfuron in cotton injury as responsible ingredient. According to the previous studies, half-life of metsulfuron was 52 days and for sulfosulfuron was 42 days in average (28). Both of them are more persistent in the soils with high pH and low organic matter like the soils in our experiment. Mesosulfuron + iodosulfuron + mefenpyre residue had somewhat adverse effects on early growth of cotton and reduced shoot dry weight, but after 50 days plants were recovered. According to Tomlin (28), half-life of mesosulfuron and iodosulfuron was reported 38 days and 8.5 days, respectively. No adverse effect was recognized in cotton plants from triasulfuron+ terbutryn and triasulfuron+ dicamba. Half-life is 19 days for triasulfuron and negligible for two other ingredients. The herbicides injures were not as much stable as cotton yields were significantly affected. In greenhouse bioassay experiment, cotton shoot DM was significantly reduced by residues of metsulfuron+ sulfosulfuron, sulfosulfuron and mesosulfuron+ iodosulfuron+ mefenpyre. In addition, residual effects of metsulfuron+ sulfosulfuron and sulfosulfuron were observed on cotton root DM. Adverse effects from metsulfuron+ sulfosulfuron and sulfosulfuron caused a significant reduction in barley. Both of these herbicides were registered for controlling of wild barley (Hordeum spontaneum K. Koch.) in wheat fields. The most residual injuries were observed in canola in which all traits were reduced by residues of herbicides used for wheat.
    Conclusion
    According to the field experiment, we found that the residues of two herbicides Total® 75% and Apyros® 75% lessened cotton height, dry matter of shoot and root at early growth stages. Nevertheless, the plant was recovered with season progress especially after overtop fertilization and consequently cotton yield (boll number, boll yield and fiber yield) was not significantly decreased. The results of pot experiment confirmed the field results and showed that these two herbicides significantly decreased cotton growth. Besides, growth of barley, canola and corn was affected by Total® 75%, Apyros® 75% and Atlantis® 1.2%. Therefore, metsulfuron and sulfosulfuron have the most effective residue among all components investigated. Moreover, canola and corn were, respectively, the most and least sensitive crops in the bioassay experiment.
    Keywords: Barley, Bioassay, Canola, Corn, Second crop, Visual injury
  • Samira Abuali, Sohrab Mahmoodi, Hossein Hammami * Pages 99-110
    Introduction
    Weed management is one of the most important aspects of successful crop production for supplying food for the rising population. Chenopodium album L. (common lambsquarter) is among the most noxious weeds in the world due to its superior biology and tremendous ecological adaptations. It causes substantial yield losses in different field crops including potato, tomato, soybean, alfalfa, watermelon, sugar beet, and so on. Therefore, management of C. album L. is crucial for optimum crop production. Chemical management is a very relevant method for controlling C. album. For decreasing costs of production, adverse and edge effects of the herbicide, optimizing herbicides performance is very essential. It seems that the use of adjuvants is the best solution method to achieve optimizing herbicides performance. Using a proper adjuvant may be affected the performance and fate of herbicide in the environment and finally may be restrict introduced to the food chain. Therefore, using proper adjuvants known as a key point in adjuvants applying technology. This study was conducted for evaluating adjuvants effects on C. album control by Bentazon+Acifluorfen and Imazethapyr herbicides.
    Materials and Methods
    In order to study the effects of adjuvants on the performance of Bentazon+Acifluorfen and Imazethapyr on C. album control two separated experiments as factorial based on completely randomized design were conducted in the research greenhouse of Faculty of Agriculture, University of Birjand in 2016. Treatments included herbicide concentration at seven levels (0, 6.25, 12.5, 25, 50, 75 and 100 % of recommended dose) and adjuvant at three levels (turnip oil, citogate and without adjuvants) with four replications. For increasing seed germination and breaking seed dormancy of C. album, the seeds treated by sulfuric acid for 1 min, and then seeds washed with tap water for 10 min. Then the seeds were sown in potting trays (3 cm × 3 cm × 5 cm) filled with moistened peat. One week after sowing, at the one-leaf seedlings stages, they were transplanted to 2-L plastic pots filled with a mixture of sand, clay loam soil, and peat (1:1:1; v/v/v). The pots were sub-irrigated every two days. The seedlings were thinned to four per pot at the two-leaf stage. The spray was done at the four-leaf stage (Four weeks after sowing) by using a chargeable sprayer equipped with an 8002 flat fan nozzle tip delivering 250 L ha-1 at 2 bar spray pressure. Four weeks after spraying, the above ground tissue and roots of plant were harvested, oven dried and weighted.
    Results and Discussion
    The results of these experiments showed that the use of additives, especially turnip oil, increased the efficacy of Bentazon+Acifluorfen and Imazethapyr herbicides in control of C. album. Turnip oil and citogate increased the efficiency of Bentazon+Acifluorfen and Imazethapyr in reducing the production of by C. album above ground tissue1.29, 1.28, 2.13, and 1.30 times, respectively. However, these values were equal to 2.79, 1.98, 2.35, and 1.66 times for reducing the root biomass of C. album. The results of this study also showed that the root was more susceptible to herbicides in the presence of adjuvants. Increasing Bentazon+Acifluorfen and Imazethapyr herbicides concentrations led to decreased dry biomass produced by C. album. Turnip oil compared to citogate showed high efficiency for improving Bentazon+Acifluorfen and Imazethapyr performance. The results of this study showed a similar trend with other scientific reports including Rashed mohassel et al (26) that reported the high efficiency of herbicides for controlling canary grass (Phalaris minor Retz.) in the presence of vegetable oils compared with mineral oils.
    Conclusion
    The result of this study showed different response of Bentazon+Acifluorfen and Imazethapyr to turnip oil and Citogate adjuvants. Therefore, applied proper herbicide adjuvant is a key factor in chemical weed management because this factor reduces herbicide rates for similar weed response. Using proper adjuvants may be increased herbicide performance more than other adjuvants. Moreover, results of these experiments revealed that root response was more than above ground tissue response to Bentazon+Acifluorfen and Imazethapyr herbicides in the presence of adjuvants.
    Keywords: Adjuvants, Broadleaf, Effective dose, Greenhouse, Relative potency
  • Mohammad Lotfi Asle Giglo, Mostafa Oveisi *, Hamid Rahimian Mashhadi, Behnaz Pourmorad Kaleibar, Mohammad Hossein Naeimi Pages 111-122
    Introduction
    Eryngium caeruleum L. is a perennial weed from Apiaceae family that grows in the farm and roadside. There is limited information on the reaction of this plant germination to temperature and light conditions. Germination is one of the most important processes for weed success, because it is the first step in competition beginning in an ecological niche. Recognition of E. caeruleum germination and emergence ecology has an important role in weed management and control. Different environmental factors, such as temperature and light, affect dormancy and germination of the seeds. Light requirement is an indicator showing the level of seed dormancy. Given the significance of seed dormancy in weed dispersal and management, this study aimed at determining the relation between light and temperature as the most effective environmental factors in germination stimulation of E. caeruleum.
    Materials and Methods
    An experiment was conducted to estimate the effect of temperature and light on germination of Eryngium caeruleum seeds at agriculture and Natural Resources College, university of Tehran in 2016. A factorial experiment was undertaken based on completely randomized block design with three replications. Factors were germination temperatures (5, 10, 15, 20, 25, 30 and 35 °C), burial periods in 5 cm depth (30, 60, 90, 120, 150, and 180 days), and light conditions during germination test (Presence and absence of light). The seeds were buried in the soil under environmental conditions at depth of 5 cm and then removed from the soil at one month intervals and were placed at dark and light (Osram, L 18 W/77, 20 µmolm-2s-1) conditions under seven temperature treatments for 14 days. 25 seeds were placed in each petri dish and the germinated seeds were counted for 14 days in each month. Segmented model was used for studying the germination rate to temperature in light and temperature treatments. Thermal parameters of germination were calculated for light and temperature treatments. These parameters were Gmax for the maximum germination rate, Tb or base temperature for germination, To or optimum temperature for germination, and Tc or ceiling temperature for germination. The base and ceiling temperature parameters were also calculated. The findings of this study shed light on seed germination requirements of E. caeruleum and enhance our understanding of this species distribution. These results will be useful in selecting the best time and method for E. caeruleum control.
    Results and Discussion
    Results showed that temperature and light conditions during germination test influenced germination rate. According to the analysis of variation, all simple effects and interactions were significant on germination rate. Germination rate increased with increasing temperature up to 20 °C. Germination rate, however, decreased when temperature increased up to 35 °C. Temperature parameters of base temperature, optimum temperature and ceiling temperature were affected by burial periods and light conditions during germination test. In general, base and optimum temperatures decreased and ceiling temperature increased with increasing of burial time. The burial time needed for 50 percent decrease of maximum base temperature in the lowest burial time was 117 days in light condition and 82 days in dark condition. The optimum temperature decreased from 23.5°C to 21.2°C in light condition and from 23°C to 21°C in dark condition. The ceiling temperature increased from 28°C to 42°C in light condition, but it had different process in dark condition. The Tc parameter was 30°C in 60 days of burial and was 28°C up to 120 days of burial and had no changes up to 180 days of burial. Parameters of Gmax and ai, which indicate the maximum germination rate and seed non-dormant index, respectively, rose linearly by increasing time of seed burial, irrespective of light condition during germination test. The same results were found in Circium arvense and Bidens pilosa, that their germination thermal parameters were higher in light condition than in dark. This can be attributed to the heat made by the light. The results of the experiment on Plygonum aviculare also showed the effects of light on cardinal temperatures of germination and the start of germination of this plant.
    Conclusion
    The results showed that the thermal parameters of Eryngium caeruleum germination including base temperature (Tb), optimum temperature (To), and ceiling temperature (Tc) changed during the burial periods. The Gmax and awakeness index parameters increased linearly regardless of the presence or absence of light. It can be also concluded that Eryngium caeruleum L. has morphophysiological dormancy and dormancy breaking. Moreover, the optimum temperature range for germination mostly rises by increasing ceiling temperature.
    Keywords: Awakens index, Germination rate, Light conditions, Thermal parameters of germination