فهرست مطالب

  • سال سی و دوم شماره 2 (تابستان 1397)
  • تاریخ انتشار: 1397/04/05
  • تعداد عناوین: 14
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  • جهان عبدزاده، آغله بوب، عصمت مهدیخانی مقدم، حمید روحانی، علیرضا چاوشین صفحات 163-171
    به منظور شناسایی نماتدهای انگل گیاهی درختان میوه هسته دار شهرستان ارومیه، طی سال های 1392 و 1393، تعداد 85 نمونه خاک جمع آوری گردید. پس از انتقال نمونه ها به آزمایشگاه، شستشوی خاک و استخراج نماتدها با استفاده از روش تغییر یافته تلفیق الک و سانتریفیوژ جن کینز (1964) و تثبیت و انتقال آنها به گلیسیرین طبق روش دگریس (1969) انجام شد. سپس از نماتدهای جدا شده به تفکیک جنس، اسلایدهای میکروسکوپی تهیه گردید. پس از بررسی های میکروسکوپی، اندازه گیری های لازم و رسم تصاویر مورد نیاز، شناسایی گونه ها با استفاده از منابع و کلیدهای موجود انجام گرفت و تعداد 11 گونه نماتد متعلق به 7 جنس شناسایی گردید که عبارتند از: Basiria duplexa، B. macrostriata، Boleodorus thylactus، Coslenchus costatus، C. gracilis، Discotylenchus longicauda، Filenchus cylindricaudus، F. vulgaris، Irantylenchus clavidorus، Psilenchus aestuarius، P. iranicus از بین جنس و گونه های شناسایی شده، گونه Basiria macrostriata از بخش نازلو، گونه های Coslenchus gracilis و Discotylenchus longicauda از بخش صومای برادوست شهرستان ارومیه برای فون نماتدهای ایران جدید بوده و برای اولین بار از ایران گزارش و شرح داده می شوند.
    کلیدواژگان: درختان میوه هسته دار، شهرستان ارومیه، نماتد های انگل گیاهی
  • طیبه سلیمانی، مجید اولیاء*، فریبا حیدری، محمودرضا تدین صفحات 173-183
    شناسایی و استفاده از ارقام مقاوم به عنوان یکی از اقتصادی ترین و بی خطر ترین روش های مدیریتی در اولویت می باشد. در این تحقیق به منظور ارزیابی عکس العمل تعدادی از ارقام سویا نسبت به نماتد ریشه گرهی (Meloidogyne javanica)، نمونه های ریشه آلوده به نماتد ریشه گرهی از یک گلخانه گوجه فرنگی در استان اصفهان جمع آوری شده و به آزمایشگاه منتقل شدند. توده تخم منفرد جدا شده از گال ها، برای تکثیر در مجاورت ریشه های سالم نشاء گوجه فرنگی رقم ps در گلدان های حاوی خاک سترون قرار داده شدند. جهت تشخیص و شناسایی گونه نماتد از خصوصیات ریخت شناسی و نشانگرهای مولکولی استفاده گردید و با توجه به الگوی خطوط شبکه کوتیکولی انتهای بدن ماده های بالغ، تکثیر باند 670 جفت بازی از DNA استخراجی از تخم، گونه نماتد M. javanica شناسایی گردید. عکس العمل ارقام مختلف سویا شامل سحر، الیت، ویلیامز، 033، L-17، DPX و JK به این گونه در آزمایشی در قالب طرح کاملا تصادفی با پنج تکرار مورد بررسی قرار گرفت. بدین منظور در مرحله 5-4 برگی ارقام سویا، تعداد 8000 تخم در 5/2 کیلوگرم خاک اطراف ریشه این گیاهان تلقیح شد. 80 روز پس از تلقیح صفات رشدی و فیزیولوژیک گیاهان شامل وزن تر و خشک ریشه و اندام هوایی به همراه طول ریشه و اندام هوایی، تعداد غلاف در بوته، تعداد دانه در غلاف، وزن دانه، نسبت سطح برگ (LIR)، شاخص سطح برگ (LIA) اندازه گیری شد. سپس برای ارزیابی میزان مقاومت ارقام، از سیستم مبتنی بر دو فاکتور تولیدمثل نماتد و میزان آلودگی ریشه استفاده شد. نتایج نشان داد که رقم JK حساس و ارقام الیت و ویلیامز متحمل می باشند و چهار رقم 033، L-17، DPX و سحر مقاوم شناخته شدند.
    کلیدواژگان: سویا، مقاومت، نماتد ریشه گرهی
  • سارا قارونی کاردانی، الهام جمشیدی صفحات 185-193
    در بررسی های انجام شده از مزارع لوبیا چشم بلبلی (Vigna unguiculata) استان آذربایجان شرقی در تابستان 1395، در برخی از بوته ها علائم ریز برگی، خشبی شدن برگ ها، فیلودی گل ها، ضخیم شدن و کتابی شدن ساقه، ازدیاد جوانه و کوتولگی بوته مشاهده شد. در گلخانه عامل بیماری به وسیله سس به پروانش انتقال داده شد و در پروانش مایه زنی شده علائم گل سبزی، برگسانی و کاهش فاصله میانگره ها ظاهر گردید. با استفاده از آغازگرهای عمومیP1/P7 و آغازگرهای آشیانه ای R16F2n/R16R2 در واکنش زنجیره ای پلی مراز (پی سی آر) از کلیه نمونه های دارای علائم قطعات 1830 جفت باز در پی سی آر عمومی و 1245 جفت باز در پی سی آر آشیانه ای تکثیر شد. در حالی که در نمونه های گیاهان سالم، قطعه ای تکثیر نگردید. محصول واکنش زنجیره ای پلی مراز پس از همسانه سازی، تعیین ترادف گردید. جستجو با برنامه Blast، آنالیز فیلوژنتیکی و بررسی چند شکلی طولی قطعات برشی (RFLP) محصول پی سی آر دو مرحله ای، با آنزیم های برشی HinfI، RsaI، AluI، TaqI، HpaII و مقایسه نقوش حاصله نشان داد که فیتوپلاسمای همراه با فیلودی لوبیا چشم بلبلی بیشترین نزدیکی را با اعضای گروه افژولش شبدر (Clover proliferation group، 16SrVI) دارد. همچنین آنالیز توالی ها با استفاده از نرم افزار iPhyClassifier و انجام RFLP مجازی با استفاده از 17 آنزیم برشی، علاوه بر تایید نتایج آنالیزهای RFLP فیزیکی و تبارزایی نشان داد که فیتوپلاسمای مورد بررسی در گروه 16SrVI-A (با ضریب تشابه 1) قرار می گیرد
    کلیدواژگان: آنالیز فیلوژنتیکی، چند شکلی طولی قطعات برشی، فیتوپلاسما، لوبیا چشم بلبلی
  • محمد احمدزاده، زاویه جیکی، احمد روحی بخش، مینا راستگو صفحات 201-203
    ویروس موزائیک زرد کدو (Zucchini yellow mosaic virus، ZYMV)و ویروس پژمردگی لکه ای گوجه فرنگی (Tomato spotted wilt virus، TSWV) از ویروس های آلوده کننده کدوییان می باشند. به منظور ردیابی ZYMV و TSWV طی سال زراعی 93، تعداد 457 نمونه ی برگی کدو، خیار، خربزه، هندوانه و طالبی مشکوک به آلودگی به این ویروس ها از مزارع کدوییان در استان گیلان و شهرستان ارومیه جمع آوری و با استفاده از آزمون الیزای مستقیم بررسی شدند. هیچکدام از نمونه ها آلودگی به TSWV را نشان ندادند. ZYMV نیز فقط در 39 نمونه ی کدو شناسایی شد. نمونه های کدوی آلوده بهZYMV به گیاهان محک مایه زنی شدند. جهت ردیابی مولکولی، از آزمون RT-PCR با استفاده از آغازگرهای اختصاصی مربوط به ناحیه پروتئین پوششی ZYMV انجام و قطعه ای به اندازه 458 جفت باز تکثیر و تبارزایی 3 جدایه از روی کدو نشان داد که این جدایه ها در گروه A که شامل جدایه های اروپایی و ایرانی است قرار می گیرند
    کلیدواژگان: توالی یابی، DAS، ELISA، RT، PCR، TSWV، ZYMV
  • بهنام امیری، مهدی کبیری ریس آباد صفحات 205-213
    کنه تارتن دو نقطه ای یکی از آفات مهم و اقتصادی در مزارع لوبیا است. در این تحقیق، اثر آفت کش گیاهی سیرینول و کنه کش شیمیایی اسپیرودیکلوفن روی تخم و بالغ این آفت در شرایط آزمایشگاهی و مزرعه ای مورد بررسی قرار گرفت. از دستگاه برج پاشش برای زیست سنجی ها استفاده شد. از سوی دیگر، به منظور بررسی غلظت های 1000، 2000 و 4000 پی پی ام از آفت کش سیرینول و غلظت های 300، 600 و 1200 پی پی ام از کنه کش اسپیرودیکلوفن، آزمایشی در شرایط مزرعه ای با 7 تیمار و 4 تکرار در قالب طرح بلوک کامل تصادفی انجام گرفت. نمونه برداری از جمعت آفت یک روز قبل، سه، هفت، چهارده و بیست و یک روز پس از تیمار انجام گرفت. میزان LC50 آفت کش سیرینول برای تخم و کنه بالغ با گذشت 72 ساعت از زمان تیمار به ترتیب 3/1192 و 3/592 پی پی ام و میزان LC50 کنه کش اسپیرودیکلوفن به ترتیب 8/289 و 9/172 پی پی ام براورد شد. بر این اساس، کنه های بالغ نسبت به تخم ها حساسیت بیشتری در برابر هر دو ترکیب ذکر شده داشتند. نتایج زیست سنجی مزرعه ای نشان دهنده دوام اثر طولانی تر آفت کش سیرینول بود. به طوری که 21 روز پس از تیمار، میزان کشندگی غلظت پشنهاد شده مزرعه ای این ترکیب برای کنه تارتن بالغ 11/92 درصد بود. همچنین سمیت این ترکیب برای کنه شکارگرAthias-Henriot Phytoseiulus persimilis بسیار کمتر از کنه کش اسپیرودیکلوفن بود. بر اساس معیارهای IOBC، آفت کش سیرینول در نمونه برداری های 21 روز پس از تیمار و در غلظت پیشنهاد شده مزرعه ای در گروه سموم با خطر کم و کنه کش اسپیرودیکلوفن در گروه سموم خطرناک برای این دشمن طبیعی دسته بندی شدند.
    کلیدواژگان: اسپیرودیکلوفن، زیست سنجی، سیرینول، کنه تارتن دو نقطه ای
  • امیر محسنی امین صفحات 215-220
    شته ریشه چغندر قندPemphigus fuscicornis Koch یکی از مهم ترین آفات چغندر قند در بسیاری از کشورها می باشد. در این پژوهش عکس العمل آفت روی 12 ژنوتیپ چغندرقند در شرایط آزمایشگاهی و مزرعه ای طی سال های 1389-1390 مورد بررسی قرار گرفت. بذور چغندرقند نخست در یک قطعه زمین در مزرعه کشت و بوته ها در مرحله شش برگ حقیقی به آزمایشگاه منتقل و پس از اطمینان از عدم آلودگی ریشه ها به شته، روی هر ریشه تعداد چهار عدد شته ماده جوان بالغ بی بال قرار گرفت و در گلدان های پلاستیکی داخل مخلوط پیت- ورمیکولیت به نسبت 50 : 50 کشت و در داخل انکوباتور با دمای 2±20 درجه سلسیوس، رطوبت نسبی 5 ± 75 درصد و 16 ساعت روشنایی و 8 ساعت تاریکی قرار گرفتند. گیاهان به صورت هفتگی آبیاری شده و پس از 60 روز جمعیت شته در ژنوتیپ های مورد آزمایش شمارش شد. نتایج نشان داد که از میان 12 ژنوتیپ مورد آزمایش، لاین 19610 در گروه خیلی حساس، OtypeA37.1 و سیمین 2 در گروه حساس، 19584، Jit13، Polyrave، و OtypeA1 در گروه نیمه حساس، زرقان، شیرین و OtypeC2 در گروه نیمه مقاوم و دو رقم Chincko و Branco در گروه ارقام مقاوم به شته ریشه چغندرقند جای گرفتند. همچنین نتایج نشان داد که در شرایط زراعی، شته عیار قند را در رقم دورتی به شکل معنی داری کاهش داد.
    کلیدواژگان: چغندرقند، ژنوتیپ، شته ریشه Pemphigus fuscicornis، مقاومت
  • اکرم نجمی، حسین صادقی، نامقی لیدا فکرت صفحات 221-229
    شته های جنس Pemphigus Harting (Hemiptera: Aphididae: Eriosomatinae) از مهم ترین شته های گال زای درختان صنوبر به شمار می روند. علی رغم اهمیت اقتصادی خسارت شته های گالزا روی درختان صنوبر، تاکنون مطالعه اختصاصی برای معرفی آنها انجام نشده است. در بررسی هایی که در بهار 1396 بر روی درختان صنوبر استان خراسان رضوی صورت گرفت، تعداد 9 گونه شته گال زا از روی درختان صنوبر به شرح زیر جمع آوری و شناسایی شدند:Pemphigus borealis Tullgren، 1909*; P. bursarius Linnaeus، 1758*; P. immunis Buckton، 1896 P. passeki Börner، 1952**; P. populi Courchet، 1879*; P. populinigrae Schrank، 1801**; P. protospirae Lichtenstein، 1885*; P. spyrothecae Passerini، 1856*; P. vesicarius Passerini، 1861.
    در بین گونه های شته جمع آوری شده، گونه هایی که با یک ستاره و دو ستاره مشخص شده اند به ترتیب برای اولین بار از خراسان رضوی و ایران گزارش می شوند.
    کلیدواژگان: بندپایان، حشرات گال زا، درختان صنوبر، فون شته ها، ایران
  • سیدکریم موسوی، علی قنبری، رضا قربانی، محمدعلی باغستانی صفحات 231-243
    به منظور تعیین کانون های آلودگی علف های هرز باریک برگ گندم وحشی و جودره در سطح مزارع گندم دیم استان لرستان شاخصی با عنوان شاخص شدت حضور علف هرز تعریف شد. شاخص شدت حضور گویای سهم هر مزرعه از کل آلودگی موجود در ناحیه مورد نظر است. ارتفاع بهینه حضور برای گندم وحشی 1856 متر و برای جودره 1703 متر از سطح دریا برآورد شد. دامنه ارتفاعی مشاهده علف هرز جودره در سطح مزارع گندم دیم استان لرستان 3/81 درصد بیشتر از دامنه ارتفاعی مشاهده علف هرز گندم وحشی بود. این موضوع گویای احتمال تهاجم بیشتر علف هرز جودره در گستره ارتفاعی وسیع تری است. مناطق شمال شرق خرم آباد، شرق الیگودرز، نواحی مرکزی سلسله و شرق با داشتن مزارع آلوده با شاخص شدت حضور بیشتر از 3/0 درصد به عنوان مهمترین کانون های آلودگی علف هرز گندم وحشی در سطح استان لرستان شناسایی شدند. در بین شهرستان های آلوده به علف هرز گندم وحشی بیشترین میانگین شاخص اهمیت نسبی (44 درصد) به شهرستان دلفان تعلق داشت، که این موضوع گویای اهمیت بیشتر آلودگی علف هرز گندم وحشی در مقایسه با سایر علف های هرز باریک برگ در این شهرستان است. میانگین اهمیت نسبی علف هرز گندم وحشی برای شهرستان الیگودرز 6/34 درصد، سلسله 2/34 درصد و خرم آباد 6/20 درصد بود. میانگین شاخص شدت حضور علف هرز جودره برای شهرستان خرم آباد 45/0 درصد، دورود 44/0 درصد، کوهدشت 34/0 درصد و سلسله 28/0 درصد بود. مزارع گندم دیم واقع در نیمه شمالی شهرستان خرم آباد، نواحی شرقی شهرستان کوهدشت، نواحی مرکزی شهرستان سلسه و نواحی شرقی دورود به عنوان کانون های اصلی آلودگی علف هرز جودره در استان لرستان شناسایی شدند. بالاترین سطح میانگین شاخص اهمیت نسبی علف هرز جودره (7/50) به شهرستان کوهدشت مربوط بود، که گویای اهمیت بیشتر علف هرز جودره در مقایسه با سایر علف های هرز باریک برگ در این شهرستان است.
    کلیدواژگان: پراکنش علف هرز، کانون آلودگی، علف های هرز باریک برگ
  • هاشم امین پناه، بیژن یعقوبی صفحات 245-255
    پیزور علفهرزی چند ساله و مقاوم به غرقاب از خانواده اویارسلام است که در سالهای اخیر جمعیت آن در مزارع برنج شمال کشور رو به افزایش است. بهمنظور کنترل شیمیایی پیزور در برنج، آزمایش مزرعهای طی دو سال متوالی در موسسه تحقیقات برنج کشور واقع در رشت اجرا شد. در سال اول، کارایی علف کش های رایج مزارع برنج شامل پرتیلاکلر، بوتاکلر، بنسولفورونمتیل، اکسادیارژیل و تیوبنکارب در کنترل پیزور مطالعه شد. بر مبنای نتایج سال اول، کارایی برخی علف کش های انتخابی و جدید از گروه سولفونیل اوره ها ( ALSها) مزارع برنج از جمله فلوستوسولفورون، پنوکسولام، مت سولفورونمتیل و نیز علف کش پیرازولیت از خانواده پیرازول ها در مقایسه با بنسولفورونمتیل در سال دوم مورد بررسی قرار گرفت. نتایج سال اول نشان داد که حداقل زیست توده پیزور در کرت های تیمار شده با بنسولفورونمتیل (5/1 گرم بر متر مربع) و پرتیلاکلر (6/10 گرم بر متر مربع) در شش هفته پس از نشاکاری مشاهده شد، درحالی که سایر علف کش ها کارایی مطلوبی در کنترل پیزور نداشتند. نتایج آزمایش سال دوم مشابه نتایج آزمایش اول، یعنی کارایی بسیار خوب بنسولفورونمتیل (97%≤) در کنترل پیزور بود. بعلاوه، نتایج نشان داد که کاربرد فلوستوسولفورون و پیرازولیت سبب کاهش معنی دار زیستتوده پیزور (91%≤) در مقایسه با شاهد عدم کنترل گردید، درحالی که علف کش های پنوکسولام و مت سولفورون تاثیر بسیار کمی در کاهش زیستتوده پیزور (49%≥) داشتند. با توجه به مکانیزم عمل متفاوت علف کش های جدید و سازگاری آنها با برنج، کاربرد آنها در تناوب با علف کش های موجود برای کنترل شیمیایی پیزور و اجتناب از مقاومت در صورت ثبت در کشور توصیه میشود.
    کلیدواژگان: برنج، علف هرز، کاهش عملکرد، کنترل شیمیایی
  • نصرت الله کریمی آربناهی، سید وحید اسلامی، رحمت الله دهقان خلیلی، محمد جواد بابایی زارچ صفحات 257-267
    به منظور بررسی اثر تنش شوری حاصل از آب آبیاری و خاک بر خصوصیات رشدی علف هرز اویارسلام ارغوانی، دو آزمایش جداگانه در قالب طرح بلوک‏ های کامل تصادفی با سه تکرار در سال 1392 در گلخانه تحقیقاتی دانشکده کشاورزی دانشگاه بیرجند انجام شد. آزمایش اول شامل پنج سطح شوری آب آبیاری (صفر، 3، 5، 7 و 9 دسی زیمنس بر متر) و آزمایش دوم شامل پنج سطح شوری خاک (1، 3، 5، 7 و 9 دسی زیمنس بر متر) بود. نتایج آزمایش شوری آب نشان داد که بیشترین میزان ارتفاع بوته (71 سانتی متر)، سطح برگ (75/79 سانتی متر مربع)، تعداد ساقه (66/6 ساقه در گلدان)، وزن خشک اندام هوایی (693/4 گرم در بوته)، تعداد غده (66/9 غده در گلدان) و وزن خشک اندام زیرزمینی (328/4 گرم در بوته) در سطح شاهد حاصل شد که با افزایش شوری آب آبیاری به 9 دسی زیمنس بر متر به ترتیب با 5/46، 2/75، 85، 1/83، 100 و 8/80 درصد کاهش همراه بوده است. در آزمایش شوری خاک نیز بیشترین میزان ارتفاع بوته (6/79 سانتی متر)، سطح برگ (75/63 سانتی متر مربع)، تعداد ساقه (7 ساقه در گلدان)، وزن خشک اندام هوایی (454/3 گرم در بوته)، تعداد غده (33/8 غده در گلدان) و وزن خشک اندام زیرزمینی (655/3 گرم در بوته) در سطح یک دسی زیمنس بر متر حاصل شد، که با افزایش شوری خاک به 9 دسی زیمنس بر متر به ترتیب با 3/44، 8/80، 95، 1/87، 76 و 38/75 درصد کاهش همراه بود. به طور کلی به نظر می رسد غده و ریزوم های اویارسلام در شرایط تنش شوری قادر به جوانه زنی و تکثیر رویشی نیستند، که این حاکی از حساسیت بالای این علف هرز نسبت به تنش شوری می باشد.
    کلیدواژگان: رشد رویشی، شوری، کلرید سدیم، مدیریت علف هرز
  • علی شایان فر، فرشید قادری فر، رحمت الله بهمرام، افشین سلطانی، حمیدرضا صادقی پور صفحات 269-278
    بذرهای کلزا پس از ریزش در بانک بذر خاک، کمون ثانویه در آنها القا می شود. در فصل زراعی بعد با رفع کمون آنها، تهدیدی برای گیاهان زراعی بعد درنتیجه تظاهر کلزای خودرو خواهند بود. در این مطالعه بذرهای با سطوح کمون ثانویه کم (Gor-H-4 و Gor-O-16)، متوسط (زرفام و RGS003) و زیاد (Gor-O-4 و Gor-O-6) کلزا ابتدا در معرض شرایط القای کمون ثانویه و سپس تحت تیمارهای مختلف دما و نور قرار گرفتند. پس از القای کمون ثانویه، حداکثر درصد جوانه زنی در بذرهای با کمون کم در دمای ثابت در تاریکی و نور ثبت گردید و کاهش درصد کمون ثانویه در بذرهای با سطوح کمون متوسط با افزایش دما از 20 به 30 درجه سانتی گراد در تاریکی مشاهده شد که روند کاهشی بیشتری را در تیمار نور نشان داد. در بذرهای با سطوح کمون بالا، روند کاهشی مشابه با بذر کمون متوسط در تاریکی و نور بود، اما در بذر با کمون بالا (Gor-O-6) بیشتر ناشی از پاسخ آنها به افزایش دما و در دیگری (Gor-O-4) بیشتر متاثر از پاسخ به نور بود. رفع کامل کمون ثانویه بذرهای با کمون بالا، در تیمار 3-30 درجه سانتی گراد در تاریکی بیانگر جایگزین شدن دمای متناوب با نیاز نوری آنها بود، اما عدم رفع کامل کمون در تیمار 20-30 درجه سانتی گراد نشان دهنده رفع کمون برخی از بذرها توسط دمای متناوب و نیاز نوری کسری از بذرها به نور است. نتایج حاکی از فتوبلاستیک شدن بذرهای کلزا پس از القای کمون است که بر نقش فیتوکروم ها بر رفع کمون ثانویه بذر کلزا اشاره دارد.
    کلیدواژگان: بانک بذر خاک، فیتوکروم ها، علف هرز
  • عادل مدحج، علی کیهانی صفحات 279-287
    رقابت علف های هرز با ذرت به عواملی نظیر نوع هیبرید، مراحل رشد گیاه، تراکم و نوع علف های هرز و میزان عناصر غذایی بستگی دارد. این آزمایش به صورت کرت های خرد شده در قالب طرح بلوک های کامل تصادفی و چهار تکرار انجام شد. در کرت های اصلی سه مقدار کود نیتروژن 90، 180 و 260 کیلوگرم نیتروژن خالص در هکتار و بدون کود، و در کرت های فرعی چهار هیبرید ذرت SC.704، DKC6589، مبین و SC.640 قرار گرفتند. هر کرت فرعی به صورت فرضی به دو بخش مساوی عاری از علف هرز و با علف هرز تقسیم شد. نتایج نشان داد که رقابت علف های هرز میانگین صفات وزن 100 دانه، عملکرد دانه، عملکرد بیولوژیکی و تعداد دانه در ردیف را به ترتیب، 3/5، 7/21، 24 و 10 درصد نسبت به شرایط وجین کاهش داد. افزایش میزان نیتروژن، اثر رقابت علف های هرز بر ذرت را افزایش داد. لاین DKC6589 به دلیل عملکرد دانه بالا در هر دو شرایط تداخل و وجین علف هرز (به ترتیب 1222و 908 گرم در متر مربع)، دارای شاخص تحمل رقابت با علف هرز (27/1) بالاتری نسبت به سایر هیبریدها بود. بطورکلی، هیبرید SC704 و لاین DKC5689 از شاخص رقابت (به ترتیب 83/1 و 08/1) بالایی برخوردار بودند. هیبریدهای مبین و SC.640 شاخص CI کمتری نسبت به SC.704 و DKC6589 داشتند. بنابراین، اگرچه دو هیبرید متوسط رس مبین و SC.640 دارای شیب خسارت عملکرد کمتری در شرایط تداخل علف هرز بودند، اما لاین دیررس و پرمحصول DKC6589 و همچنین هیبرید SC.704 از عملکرد بالا و قدرت پایداری عملکرد بیشتری در شرایط رقابت با علف هرز برخوردار بودند
    کلیدواژگان: تداخل علف هرز، ژنوتیپ، شاخص های رقابت
  • سیده مریم مظفری، حمیدرضا محمددوست چمن آباد، حمیدرضا نیکخواه صفحات 289-297
    امروزه، شناسایی ارقام گیاهان زراعی با توانایی رقابت بالا راه حل آسان و ارزانی برای مدیریت علف های هرز در سیستم های کشاورزی پایدار به شمار می رود. به همین منظور آزمایشی در سال زراعی 95-1394 در مزرعه تحقیقاتی دانشکده کشاورزی و منابع طبیعی دانشگاه محقق اردبیلی اجرا شد. برای این منظور 25 رقم گندم، از ارقام پاییزه، بهاره و بینابین در حضور و عدم حضور علف های هرز در شرایط طبیعی کشت شد. مساحت هر کرت 10 متر مربع (2×5) بود که هر کرت پس از کاشت بذر به دو قسمت مساوی (5/2×2) تقسیم شد. در یک قسمت علف های هرز در طول فصل رشد کنترل شد و در قسمت دیگر علف های هرز در طول فصل رشد حضور داشتند. طرح آزمایشی در قالب بلوک های کامل تصادفی در سه تکرار اجرا شد. برای طبقه بندی ارقام گندم صفاتی از جمله بیومس، ارتفاع و درصد پوشش اولیه ارقام، ارتفاع نهایی، عملکرد و اجزای عملکرد ارقام در هر دو شرایط رقابت و بدون رقابت اندازه گیری شد. نتایج نشان داد که بین تراکم علف های هرز با صفات اولیه رشد ارقام گندم (وزن خشک، درصد پوشش و ارتفاع) هیچ همبستگی معنی داری مشاهده نشد، درحالی که همبستگی منفی بالایی بین وزن خشک علف های هرز با این صفات وجود داشت. در بین این صفات، درصد پوشش اولیه بیشترین همبستگی منفی (**70/0-=2R) را با وزن خشک علف های هرز داشت. همچنین، بین عملکرد و اجزای عملکرد دانه ارقام گندم با تراکم علف های هرز همبستگی معنی داری مشاهده نشد، درحالی که با وزن خشک علف های هرز همبستگی منفی بالایی داشتند. ارقام گندم بر اساس صفات مورد مطالعه و با استفاده از تجزیه کلاستر و بای پلات در چهار گروه اصلی قرار گرفتند. گروه اول ارقامی با پتانسیل تولید نسبتا بالا و حساس به علف هرز بودند، بطوری که میانگین عملکرد آنها در شرایط عاری از علف هرز 8/1 برابر بیش از عملکرد در شرایط رقابت بود. گروه دوم شاخص تحمل بالای داشتند و افت عملکرد در آنها نسبتا پایین و بین 20 تا 30 درصد بود. ارقام گروه سوم دارای پتانسیل تولید پایین و حساسیت بالا نسبت به علف های هرز بودند. در این ارقام افت عملکرد بیش از 50 درصد بود. گروه چهارم که فقط رقم سیوند قرار داشت پایین ترین افت عملکرد و بالاترین شاخص رقابت را در بین ارقام مورد مطالعه داشت. نتایج این تحقیق نشان داد که طبقه بندی ارقام گندم ایرانی براساس توانایی رقابت می تواند به عنوان یک ابزار با ارزش برای مدیریت تلفیقی علف های هرز در اختیار کشاورزان قرار گیرد.
    کلیدواژگان: ارقام، شاخص رقابت، محصول سالم، مدیریت تلفیقی
  • اکبر علی وردی صفحات 299-306
    برای کاربرد ایمن و بهینه ی علف کش ها لازم است که بادبردگی به بیرون از منطقه ی سمپاشی2 و هدرروی آن در درون منطقه سمپاشی3 به حداقل رسانده شود. در این ارتباط، یک تصمیم مدیریتی بحرانی می تواند انتخاب نازل مناسب برای پاشش علف کش در شرایط بادی مختلف باشد. در یک آزمایش دز-پاسخ، شش مقدار از ستوکسیدیم با استفاده از چهارده نوع نازل 11002 در دو سرعت وزش باد 5/0 و 5/9 متر در ثانیه بر روی یولاف وحشی زمستانه در مرحله پنج برگی پاشیده شد. نازل بادبزنی استاندارد دوقلو و نازل بادبزنی دوقلوی القاکننده هوا 3070 به ترتیب در سرعت وزش باد 5/0 و 5/9 متر در ثانیه به عنوان مناسب ترین نازل برای پاشش ستوکسیدیم با یک حجم حامل استاندارد 210 لیتر در هکتار علیه یولاف وحشی زمستانه تعیین شدند. در سرعت وزش باد 5/0 متر در ثانیه، با افزایش اندازه قطرات ایجاد شده به وسیله نازل ها (کیفیت قطرک سازی)، مقدار ستوکسیدیم مورد نیاز برای کاهش 50 درصدی در وزن خشک یولاف وحشی زمستانه افزایش یافت که نشان دهنده آن است که کارایی علف کش کاهش یافت. در سرعت وزش باد 5/9 متر، با افزایش اندازه قطرات ایجاد شده به وسیله نازل ها از بسیار ریز تا درشت مقدار ستوکسیدیم مورد نیاز برای کاهش 50 درصدی در وزن خشک یولاف وحشی زمستانه کاهش یافت که نشان دهنده آن است که کارایی علف کش افزایش یافت
    کلیدواژگان: بادبردگی، دز، پاسخ، دو بادبزنه، علف کش، یک بادبزنه
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  • Jahan Abdzadeh Aghlebub, Esmat Mahdikhani Moghadam, Hamid Rouhani, Alireza Chavshin Pages 163-171
    Introduction
    The rose family includes many economically important fruit trees known as stone fruits in the genus Prunus, with a basic chromosome number x=8, within the subfamily Pronoidaea. The subfamily is unique among the rosaceous subfamilies, in bearing a fleshy fruit called a drupe with a hard endocarp, often called the stone. Many Prunus species are compatible with the link. This adaptation is very important in the production of commercial fruit. The purpose of using base-link compounds is that plant materials adapt to soil types and climatic conditions. There are different genera of plant parasitic nematodes in rhizosphere such as Amplimerlinius, Basiria, Boleodorus, Coslenchus, Discotylenchus, Filenchus and Psilenchus. Some of them are endoparasites and others ectoparasites. From the economic point of view, fruit-bearing trees are considered to be high-value agricultural products that are cultivated in most parts of the country. Urmia city is one of the major suppliers of fruit in the country. According to Agricultural Statistics in 2013, West Azerbaijan province with 99205.97 hectares of garden products produces 82.3 percent of the total land production in the country, which is ranked seventh in the country. Also in the same year, producing 1075465.73 tons of produce, 74.6% of the total production of garden products and the third rank of the country. In the year 92, the total amount of the country's garden products (about 227 thousand hectares) is related to the nuclear trees, of which 1.89 million tons were obtained, accounting for 11.84 percent of the total production of horticultural products Country is West Azerbaijan province has 2677.06 hectares of unpolluted levels and 1911.20 hectares of fertilized surfaces dedicated to nuclear products, of which 105575.26 tons of nuclear fruit production were produced from these lands. Therefore, due to the importance of nematodes from different aspects such as their high diversity, economic damage to plants in high populations, the intensification of damage to other pathogens in plants, and with regard to the few studies carried out, in particular in the field of plant-parasitic nematodes of the rhizosphere of nucleated fruit trees in West Azerbaijan Province. The aim of this research was to investigate the plant parasitic nematodes associated with stone fruit trees in the Urmia county.
    Material and
    Methods
    In order to identify plant-parasitic nematodes of stone fruits in Urmia, 85 soil samples were collected during 2013 and 2014. Soil samples were washed and then extracted by centrifugal flotation technique, killed, fixed and transferred to Glycerin by using the method of De Grisse 1969 and Jenkins 1969. The permanent slides were prepared and nematodes were studied by light microscopy, based on morphological and morphometric characters.
    Result and
    Discussion
    In this research, 11 species of seven different genera of Tylenchidae family were identified as follows: Basiria duplexa, B. macrostriata, Boleodorus thylactus, Coslenchus costatus, C. gracilis, Discotylenchus longicauda, Filenchus cylindricaudus, F. vulgaris, Irantylenchus clavidorus, Psilenchus aestuarius and P. iranicus.In this research, the categorization of the Daily and Blacksters, which is provided up to the family level, is considered, and for lower levels, other sources are used as needed, as stated in the text. Among these identified species, Basiria macrostriata from Nazlou and Coslenchus gracilis and Discotylenchus longicauda from Somaybradoust were reported as a new record for Iran. Basiria macrostriata was identified by these characters: cuticle coarsely striated being 1.8-2 (µm) apart on mid-body region. Lateral field with four crenate incisures. Head almost continuous and rounded. A Slender stylet with the flanged knob. Basal bulb more or less pyriform. Excretory pore situated at 89 (µm) from anterior end. Spermatheca sac-like and elongate. Slender filiform tail with a pointed terminus. Coslenchus gracilis was identified by cuticular annuli flattened indistinct. Stylet knobs small, 7-8(µm), rounded or slightly elongated. Median bulb spherical, Vagina strongly swollen, slightly anteriorly directed. Spermathecabilobed and containing minute sperm. Annulation on tail indistinct. Discotylenchus longicauda was identified by body straight, maximum width 9-11(µm). cuticular annuli indistinct. The Lateral field comprising a single ridge formed by two smooth incisures. Stylet thin, cone 1/3 of its length. Median bulb spindle-shaped. Vulva transverse, open. Tail straight, elongated, filiform, gradually tapering to the rounded tip.
    Conclusion
    Among these species in this research, from 11 species of seven different genera of plant parasitic nematodes, Basiria macrostriata, Coslenchus gracilis, and Discotylenchus longicauda were identified for the first time from Iran.
    Keywords: Plant, parasitic nematodes, Stone fruit trees, Urmia county
  • Tayebh Solimani, Majid Olia, Fariba Heydari, Mahmoudreza Tadayon Pages 173-183
    Introduction
    Using nematode-resistant cultivars is the most economical and environmentally friendly management strategy for the management of the pathogens like nematodes known for causing great yield losses. Root knot nematode (Meloidogyne javanica) is distributed in all soybeans - producing regions of the world and can result in yield losses in almost all soybean-growing areas. The most important species in Iran is M. javanica, which has the widest host ranges of any of the root-knot nematodes. Control of M. javanica is accomplished through the use of pesticides, crop rotation and resistant cultivars. Resistance to nematodes is usually defined as a plant’s ability to inhibit nematode reproduction. Soybean, Glycine max (L.) Merrill, which had economic and nutritional significance, is currently the most important oil - seed crop cultivated in the world. The relationship between crop yield response and initial nematode densities is an important property of a crop resistance. The purpose of the current study was to determine damage functions of M. javanica for some soybean cultivars.
    Materials And Methods
    The experiments were conducted under greenhouse conditions and temperature maintained at 25±3°C. Pots (2500 grams) were fumigated with methyl bromide to eliminate existing biotic factors prior to planting and then were filled with a sterile soil composed of sand 60%, clay 14%, silt 26%, at pH 7. For evaluating the reaction of some soybean cultivars to the target nematode, infected roots collected from Isfahan province, identified using morphological methods, perineal pattern of adult females as well as molecular markers, amplification of 670 bp band of extracted DNA from egg and larvae using single egg mass culture. Then the nematode mass was cultured around the roots of 2-4 leaf stage tomato cultivar Ps using completely randomized design with five replications. Soybean plants inoculated with 8000 eggs of M. javanica per 2.5 kg of soil. After 80 days, the growth and physiologic factors of host plant such as root length, root fresh and dried weight, shoot length, shoot fresh and dried weight, pod number in plant, seed per pod, 100- seed weight, chlorophyll concentration, leaf area index (LAI) and leaf area ratio (LAR) as well as gall index, egg mass and reproductive factors of nematode was measured.
    Results And Discussion
    The purpose of this study was to determine damage function of M. javanica for some resistant and susceptible soybean cultivars. Similar to M. javanica, the other nematode species was identified using morphological as well as molecular markers as. In greenhouse condition, results showed that the root weight of the infected soybean cultivars increased in comparison to that of healthy roots and the reason is the hormonal imbalance and the gall formation in the roots by the target nematode. The shoot length and shoot fresh weight in infected plants decreased due to the absorption of nutrients and internodes distance reduction. Seed per pod is dependent characteristics on the genotype, and largely is independent of environmental factors and specific environmental stresses may affect grain formation period. The number of seeds per pod was completely genetic trait, indicating significant differences among cultivars, but the cultivars were not affected by nematode infection. The JK cultivar has the most final population of nematodes and Sahar cultivar has the least one. The JK cultivar was sensitive to 2.65 gall index and Williams and Elit cultivars were tolerant and showed less gall index and Sahar, L- 17, 033 along with DPX were recognized as resistant soybean cultivar, among which Sahar cultivar with 0 reproductive factor and 0.6 gall index was most resistant one. The use of resistant soybean cultivars is the most efficient and control methods for root- knot nematode.
    Conclusions
    The different soybean cultivars have varying degrees of sensitivity, tolerance and resistance to root-knot nematode infection. The present research indicates that using breeding methods as well as biotechnological techniques, tolerant and resistant cultivars can be produced and the farmers can choose the resistant ones to reduce application of hazardous chemicals. On the other hand it is necessary that by a thorough examination of nematode resistant genes in soybean plants and their incorporation in the sensitive plant, the nematode damage would get reduced. The use of resistant soybean cultivars is the most efficient and adequate control measure.
    Keywords: Glycine max, Meloidogyne javanica, Resistant cultivar
  • Sara Gharouni Kardani, Elham Jamshidi Pages 185-193
    Introduction
    Phytoplasmas were first discovered in 1967 and named mycoplasma-like organisms or MLOs. They are wall-less prokaryotes of the class Mollicutes causing diseases in many economically important plant species. Phytoplasmas are transmitted by phloem-feeding leafhoppers and planthoppers. Plants infected by phytoplasmas exhibit a variety of symptoms suggesting profound disturbances to the normal plant physiology. Restriction fragment length polymorphism (RFLP) and sequence analyses of rDNA have been used for the taxonomic characterization and phylogenetic analysis of phytoplasmas. Because of the high economic losses, in particular those of cultivated crops, annuals and high-value vegetables, detection of phytoplasmas is very important. Cowpea (Vigna unguiculata) is an important vegetable crop cultivated in Iran. Progressive growth abnormalities and phyllody symptoms with high economic loss have been observed in cowpea fields of East Azarbaijan province. Causal agent of the disease is, however, unclear. This study was, therefore, carried out to identify pathogen associated with cowpea phyllody in East Azarbaijan province of Iran.
    Materials And Methods
    Infected cowpea plants were collected from fields in East Azarbaijan province of Iran in summer of 2016. The disease agent was transmitted by dodder to periwinkle plants under controlled greenhouse conditions. Leaf midribs from healthy control and naturally-infected hosts were used for DNA extraction. Total DNA was extracted from midrib of six symptomatic cowpeas, inoculated periwinkle plants using CTAB buffer as previously described by Zhang et al., 1998. The universal primer pair P1/P7 was employed in first round PCR to amplify an 1830 bp fragment of 16S rDNA. A 30-fold dilution of the first round PCR product was then used as template for nested PCR using primer pair R16F2n/R16R2 which amplified an internal fragment of 1245 bp from the 16S rDNA. PCR products were ligated into pTZ57R/T using InsT/AcloneTM PCR Product Cloning Kit and transformed to Escherichia coli DH5a cells. The recombinant plasmids were sequenced. The sequences were assembled using DNA baser V. 3 program. About 100 ng of DNA from R16F2n/R16R2 primed PCR product from each province was separately digested with 2.5 μL of AluI, HaeIII, HpaII, HinfI, RsaI and TaqI restriction enzymes according to the manufacturer’s instructions. Restricted DNA fragments were analyzed by electrophoresis through a 2% agarose gel. Phylogenetic tree was generated using neighbour-joining method with MEGA7 software. Acholeplasma laidlawii, a culturable mollicute that is phylogenetically related to the phytoplasmas, was designated as the out-group to root the tree. The reliability of the tree was assessed by bootstrap analysis with 1000 times replication. Further, the sequences of the 16S rRNA gene were subjected to virtual restriction fragment length polymorphism (RFLP) using iPhyClassifier software (http:// plantpathology. ba. ars. usda. gov/ cgi- bin/ resource/ iphyclassifier. cgi) to determine ribosomal group affiliation.
    Results And Discussion
    Cowpea plants collected from East Azarbaijan province showed disease symptoms similar to those caused by phytoplasmas. In infected cowpea plants, symptoms of little and thickened leaves, phyllody, proliferation of shoot, wrinkled and malformed leaves, stem fasciation and stunting were observed. Inoculated periwinkles showed little leaf, internode shortening, yellowing, virescence, phyllody, stem and floral proliferation and witches’ broom. Amplification of 1830 and 1245 bp fragments in PCR and nested-PCR, respectively, and Blast analysis of the fragment sequences confirmed phytoplasma infection of cowpea plant associated with phyllody symptoms. No band was found at healthy control. Consensus sequences of 1,830 bp of three isolates (Tabriz, Nazarlou, Shabestar) were submitted in the NCBI GenBank under accession numbers KC633092 to KC633094. Phylogenetic analyses and restriction fragment length polymorphism (RFLP) of 1245 bp fragment with 17 restriction endonucleases using iPhyClassifier software indicated that phytoplasma associated with cowpea phyllody belong to Clover proliferation group or 16SrVI A subgroup (similarity coefficient 1.00).
    Conclusions
    Tomato (Solanum lycopersicum), potato (Solanum tuberosum), cucumber (Cucumis sativus), cabbage (Brassica oleracea) and periwinkle (Catharanthus roseous) were reported as hosts for 16SrVI phytoplasma group in Iran. Recently, maize (Zea mays) has also been reported as a natural host of the 16SrVI group. In addition, different phytoplasma groups and subgroups were reported infecting cowpea crops from different countries over the globe. A 16SrXII-B strain of 'Ca. Phytoplasma australiense' associated with witches’ broom and small leaves of V. unguiculata var. sesquipedalis in Australia. A Vigna little leaf phytoplasma belonging to group 16SrV has also been reported from Australia. In India, different phytoplasmas associated with cowpea from 16S rDNA groups 16SrI-B, 16SrXIV-A and 16SrII-D, have been characterized. Identification of the causal agent of phyllody of cowpea in Iran should facilitate studies concerned with epidemic aspects of the disease, and could contribute to knowledge of the genetic diversity of phytoplasmas in Iran. To the best of the present study authors’ knowledge, it is the first report of the Vigna unguiculata infection with phytoplasmas related to the “Clover Proliferation Group” from East Azarbaijan province of Iran.
    Keywords: Cowpea (Vigna unguiculata), Phylogenetic analyses, Phytoplasma, RFLP
  • Mohammad Ahmadzadeh, Ahmad Rouhibakhsh, Mina Rastgou Pages 201-203
    Introduction
    Cucurbit plays an important role in human nutrition because of an ingredient of vitamin and other dietary substances. Cucurbit crops are very sensitive to viral infection. Over 35 viruses from Cucurbitaceae family have been reported. Plant viral diseases are major limiting factors for successful cultivation causing major yield losses in agricultural crops worldwide. Zucchini yellow mosaic virus (ZYMV) is a member of the genus Potyvirus, in the family Potyviridae has flexuous filamentous particles of about 750 nm in length and consists of a single-stranded RNA about 9.5kb. It was first reported in Italy in 1981. ZYMV is transmitted by certain species of aphids, by plant sap containing the virus and through infected seeds. ZYMV is one of the major pathogens of the family Cucurbitaceae. The common symptoms of ZYMV infection are local lesions, chlorotic mosaic, vein banding, yellowing, and stunting. Thrips-transmitted tospoviruses are economically important viruses affecting a wide range of field and horticultural crops worldwide. Tomato spotted wilt virus (TSWV) is the type member of the Orthospovirus genus in the family Tospoviridae with a broad host range of more than 900 plant species. TSWV has tripartite, ambisense, and single-stranded (ss) RNA genome transmitted by thrips in propagative and persistent manner and is ranked second among the top ten economically important viruses in the world. The aim of this research was to serological and molecular detection of ZYMV and TSWV on cucurbits of Guilan province and Urmia county and concerning their phylogenetic relationship with other isolates of the world.
    Materials And Methods
    In order to detect ZYMV and TSWV during the growing season of 2014, a total of 457 leaf samples of squash, watermelon, cucumber, melon and cantaloupe showing virus symptoms were collected from different fields of Guilan province and Urmia vicinity. DAS-ELISA was carried out on all samples using specific polyclonal antisera and samples with values at least twice the value of the negative control value according to the absorbance at 405 nm was accepted as positive. The samples which showed positive result in ELISA test were inoculated to Chenopodium amaranticolor Coste et Reyn, C. quinoa Wild., Cucumis melo L., Cucurbita pepo L., Lycopersicon esculentum L., Nicotiana rustica, N. tabacum var. Samsun and Gomphrena globosa L. Total RNA were extracted from positive samples in ELISA (for ZYMV) using RNXTM (-Plus) kit and RT-PCR was performed using ZYMV and TSWV specific primers corresponding to the CP and L-gene of these viruses, respectively. PCR positive products were sent for sequencing from both sides. Sequences were compared to data available in GenBank and multiple alignments of the nucleotide sequences and a phylogenetic tree were constructed by MEGA6 using the neighbor-joining method with a 1000 replicate bootstrap search.
    Results And Discussion
    Among 457 symptomatic samples collected from cucurbit fields of Guilan province and Urmia vicinity showing viral symptoms, 39 squash samples were infected by ZYMV but none of them by TSWV in ELISA test. Almost all inoculated plants showed symptoms of infection by ZYMV described in literature them. But this was different symptoms. An amplicon of the expected size (458 bp) was generated from ELISA positive samples during RT-PCR using specific primers but not from the healthy sample and no positive result for TSWV. Two PCR-positive samples of Guilan province and one Urmia isolate were sequenced and submitted to BLASTn. The results revealed that the PCR-amplified fragments of all samples belonged to ZYMV. The Kiashahr and Astaneh isolates showed maximum similarity (98%) with Czech Republic and Iran (Fars) isolates, and Urmia isolates showed the highest homology (99%) with Slovakia isolate in group A.
    Conclusions
    Viruses are known to greatly reduce cucurbitaceous yield. ZYMV is one of the most destructive and widespread plant pathogens. In this study, for the first time, molecular detection of ZYMV in squash fields of Guilan province and Urmia vicinity has been reported concerning its phylogenetic relationship with other isolates of the virus available in the GenBank. Phylogenetic analyses based on CP gene indicated that the Iranian ZYMV isolates are closer to European isolates plus one Iranian isolate and clustered in group a clade. The data obtained in this study will be beneficial to improve control strategies for this virus in Iran and are the base for further work on ecology, epidemiology, and diversity of these viruses in these two regions. Further studies on ZYMV isolates from different geographic regions and hosts of these two regions and genetic diversity evaluation of the virus will be useful for breeders to make more efficient and durable resistant cultivars. TSWV was not detected in cucurbits of these two regions during this study. It has been reported only in Malaysia on cucurbits.
    Keywords: DAS, ELISA, RT, PCR, Sequencing, TSWV, ZYMV
  • Behnam Amiri-Besheli, Mahdi Kabiri-Res Abad Pages 205-213
    Introduction
    The two-spotted spider mite is a cosmopolitan species that exist in wide areas of the world and fed from different varieties of plants. The control of this pest was done by chemical pesticides and acaricides. Due to the high cost of chemical compound and problems such as durability and environmental pollution, alternative control means are necessary. Plants may provide potential alternatives to currently used insect control agents. Plant materials have several advantages over traditional pest control agents; such as specificity, biodegradability and low mammalian toxicity. Sirinol is a natural compound based on garlic extract. Spirodiclofen with a trade name of Envidor® is a broad spectrum acaricide acting via lipid biosynthesis inhibition (LBI) with no cross-resistance to currently available acaricides and with additional insecticidal properties. Envidor is positive IPM listed but in the frame of resistance, management limited to one application per season. In pear growing Envidor constitutes an important tool in pear sucker control in a tandem strategy with abamectin. In this research, the effect of this compound was investigated on the egg and adult of T. uricae under laboratory and field condition.
    Materials and Methods Rearing of T. urticae: An initial mite colony was collected from infected fields in Sari and was transferred to the laboratory in Sari Agricultural Science and Natural Resource University, plant protection department. The adult mites were released on the bean leaves (3 weeks after leaves germination) and removed 24 h after treatment. Infected plants to mite eggs were placed in a growth incubator at 25±2˚C, 65±5% RH and 16:8 photoperiods. 12 days after treatment and emerging of adults, they were used for the bioassay.
    Bioassay: First of all, primary experiments were performed to determine the minimum and maximum concentrations. Then, seven concentrations and also control were considered. The concentrations used for sirinol were 250, 381, 593, 922, 1434, 2230 and 3500 ppm and for spirodiclofen were100, 134, 180, 242, 326, 438 and 600 ppm. The original bean leaf discs (30 mm diameter) were cut and 15 adults of T. urticae were released on each leaf. Then, 500 microliters of each concentration was sprayed on the leaves using spray potter tower and the leaves were put on the petri plates containing moist cotton. The treatments were placed in a growth incubator at 25±2˚C, 65±5% RH and 16:8 photoperiods. The number of dead mites was counted at 24, 48 and 72 hours post-treatment. To evaluate the effect of three concentrations 1000, 2000 and 4000 ppm of sirinol and 300, 600 and 1200 ppm of spirodiclofen an experiment with seven treatment and four replications was conducted in a randomized complete design under field condition. The numbers of T. urticae and P. persimilis (egg and adult) on leaf samples were counted one day before treatment and 3, 7, 14 and 21 days after treatment.
    Statistical analyses: The mortality results were analyzed statistically using SPSS data processing software. Significant differences among the groups were determined using the unpaired Duncan-test. A value of P
    Keywords: Bioassay, Sirinol, Spirodiclofen, Two, spotted spider mite
  • Amir Mohseni Amin Pages 215-220
    Introduction
    Plant resistance to insect pests as a method of pest control in the context of IPM has a greater potential than any other method of pest suppression. Development of crop varieties resistant to insect pests and diseases has been the major research thrust at ICRISAT (International Crops Research Institute for the Semi-Arid Tropics) for sustainable crop production. The most attractive feature of host plant resistance (HPR) is the simplest seed-based technology for which farmers do not need any extra skills concerning the application, and any additional cash investments. Sugar beet root aphid Pemphigus fuscicornis Koch (Hem.: Aphididae) is one of the most important pests of sugar beet, Beta vulgaris L. in many countries. Variability in response to root aphids by commercial varieties is demonstrated by Campbell and Hutchison (1995). Sugar beet variety trials in the western plains region have shown that sugar beet varieties vary greatly in the level of resistance to sugar beet root aphid feeding. Correlative data from these trials in Nebraska, Wyoming and Colorado indicate that varieties being susceptible to root aphids had the yield reductions as much as 30% compared to those varieties with a high level of resistance. Cultivars resistant to root aphid, Pemphigus spp. have been highly successful and the resistance has been stable for more than 30 years in Texas or other areas. Several seed companies have had trouble developing resistant cultivars and even those companies with resistant parental lines required an evaluation of new hybrids.
    Materials And Methods
    In this research that was carried out during 2010- 2011, the responses of Pemphigus fuscicornis to 12 sugar beet genotypes (19610, OtypeA37.1, Simin2, 19584, Jit13, Polyrave, OtypeA1, Shirin, Zarghan, OtypeC2, Chinock, Branco) were examined under the laboratory conditions. The sugar beet seeds were planted in the field, and plants were grown to 6 true leaf stages, then were transplanted into a peat-vermiculite mix (50:50) in pots. Four young adult aphids were placed in the root mass before placement into the pot. The plants were irrigated weekly and the incubator was set at 20±2ºC and 16 h in the artificial light. Sixty days after root infestation, the aphid populations were evaluated by floating aphids out of the root mass in 20-cm diameter bowls and they were classified as adults and nymphs based on the presence of the sub-genital plate as an indicator of maturity. Therefore, all count data were transformed by log (x) before the analysis. Statistical analyses were performed using SAS statistical software (SAS Institute Inc, Version 9.1) and means comparison of treatments were done by Tukey's tests.
    Results And Discussion
    Sugar beet variety trials in the laboratory conditions have shown that sugar beet varieties vary significantly in the level of resistance to P. fuscicornis feeding. There was a significant difference among aphid population densities with regard to different host plant varieties (F=10.56, df=11, 43., P=0.0001). Out of 12 genotypes, line 19610 was highly susceptible, OtypeA37.1 and Simin2 were susceptible, 19584, Jit13, Polyrave and OtypeA1 were moderately susceptible, Zarghan, Shirin and OtypeC2 were moderately resistance and Chincko and Branco were resistance to P. fuscicornis at laboratory condition. Also, the effect of root aphid infestation on the sugar content of plant showed that, P. fuscicornis significantly decreased the sugar content (F=42.05, df=3, P=0.0001) in Doreti variety at field conditions. So, more than 15 percent of infestation to root aphid at harvest time significantly decreased the sugar content.
    Conclusions
    Based of the present results, it is concluded that planting of resistant varieties (Chincko and Branco) or moderately resistant varieties (Zarghan, Shirin and OtypeC2) will have a significant effect on reducing the aphid damage in this area. However, it is recommended that these varieties to be examined under greenhouse or field conditions. In this research, screening for resistance has been carried out under laboratory conditions. Laboratory tests are useful to confirm the resistance observed under field conditions. Procedures for infestation and evaluation of resistance under field, greenhouse or laboratory conditions using artificial infestation need to be standardized to breed for plant resistance to this pest. Insecticides have been unsuccessful for controlling root aphid, P. fuscicornis and for chemical control to be effective, a soil drench or systemic action through the sugarbeet plant may be necessary.
    Keywords: Genotypes, Pemphigus fuscicornis, Resistance, Sugar beet
  • Akram Najmi, Hossein Sadeghi Namaghi, Lida Fekrat Pages 221-229
    Introduction
    Poplar trees in Iran are hosts to a number of aphid species, some of which cause excrescences on leaves and other growing parts. These abnormal growths are classified as either galls or pseudogalls but innumerable gradations between the apparently normal and abnormal plant structures have made differentiation difficult. Galls are vegetable excrescences resulting from insect activities and usually sheltering the immature stages of the producers. The aphid genus Pemphigus Hartig, 1839 (Hemiptera: Sternorrhyncha) contains over 70 species widely distributed in the Holarctic, of which, 46 are known to form galls on leaves or twigs of Populus L. Aphids of the genus Pemphigus are usually holocyclic and heteroecious between a primary host, and several herbaceous secondary hosts. The majority of the family representatives are dioecious or heteroecious. Such species migrate from primary hosts (tree species) where they form galls characteristic in their size and shape to roots of secondary hosts (herbs or tree species). Only few species are monoecious, i.e. with life cycle occurring on one host species. Reviewing taxonomic related literature showed that the knowledge of Iranian galling aphids is still limited. So far 7 species e.g. P. borealis Tullgren, 1909, P. bursarius Linnaeus, 1758, P. immunis Buckton, 1896, P. populi Courchet, 1879, P. protospirae Lichtenstein, 1884, P. spyrothecae Passerini, 1856 and P. vesicarius Passerini, 1861 have been reported from Iran.
    Materials And Methods
    This study was conducted during the growing season of 2017. The study area, Razavi Khorasan province (35.1020° N, 59.1042° E) is located in the North eastern Iran, where no study has previously been carried out. The galls were collected from the leaves, petioles and branches of poplars, according to their location, and taken from them. Also some galls with aphids were put into vials filled with 75% alcohol for morphological studies. Sampling, preparation and identification of specimens were done according to the Blackman and Eastop (2000)). Specimens was approved by Dr. Roman Hałaj in Entomological Laboratory of the Upper Silesian Nature Society of Poland. Systematic knowledge, host plants, and synonyms of determined species were taken from Blackman and Eastop (2000) and Rezvani (2001).
    Results And Discussion
    Nine gall-inducing aphid species belonging to genus Pemphigus, Tribe Pemphigini and subfamily Eriosomatinae were found on four host plants. The occurrence of Pemphigus passeki (Börner), 1952 (Hem.: Aphididae) and Pemphigus populinigrae (Schrank), 1801 (Hem.: Aphididae) on Populus nigra in Iran are reported for the first time. The other recorded gall aphids are: 1-Pemphigus borealis which its galls are more or less oval in shape with a rather smooth surface galls, often merged into groups of 4-6 at the base (even up to 10). 2-Pemphigus bursarius with galls of more or less spherical, pear-shaped or pouch-like, green, yellow-green, sometimes red-brown in color. 3- Pemphigus immunis which its galls are walnut shape (c.a 4 cm in diameter), with think walls and uneven, wrinkled and often cracked surface, usually occurring individually, less often in small groups but always separated from one another. 4- Pemphigus passeki with galls at the base of the lamina, this gall was collected only from Neyshabour city. 5- Pemphigus populi with gall of more or less spherical or oval, more or less irregularly blobbed, almost always narrower at the base than at the top, pear-shaped or even slenderer, placed on the upper side of the lamina on the main nerve usually close to its base, size of a hazelnut, most often green in color. 6- Pemphigus populinigrae Schrank, 1801 with elongated galls and running along the main nerve, rather smooth, in their majority bright reddish and rather without yellowish tint, only partly open from the bottom side of the lamina. 7- Pemphigus protospirae with flattened and strongly spirally twisted galls, the twists are smaller and more numerous (more than 5) than those formed by P.spyrothecae. Galls very often on all the petiole and the base of lamina, shiny, green or green with red spot. 8- Pemphigus spirothecae with galls in the form of flattened and spirally twisted petiole, with the number of twists not exceeding 5 (usually 3-5). Galls are green, yellow-green to red-brown. 9- Pemphigus vesicarius with galls of combe-like, crown like or club-shaped, always with very distinct processes.
    Conclusions
    This preliminary research on gall-inducing aphids and their host plants in NE Iran added two new records of species to Iranian aphid fauna and 5 new records to Razavi Khorasan province. Previously about 485 aphid species were known for Iran. By the present study, the Iranian aphid fauna has at least 487 species. However, the number of insects especially aphids recorded from Iran is far from complete. Most probably due to the fact that the Iranian fauna has been poorly investigated and many areas have been sampled only sporadically
    Keywords: Aphid fauna, Gall maker aphids, Iran, Poplar trees
  • Seyed Karim Mousavi, Ali Ghanbari, Reza Ghorbani, Mohhamad Ali Baghestani Pages 231-243
    Introduction
    Distribution characteristics of weed species are key variables for weed management. Abundance and frequency show the number of individuals of a population in a given area. Distribution is a measure of the geographical domain of weeds. Identification of environmentally suitable areas for invasive of weed species is a great opportunity for management of weed invasion.
    Materials And Methods
    In order to specify the infection hotspots of wild wheat (Triticum boeoticum Boiss) and wild barley (Hordeum spontaneum K.Koch) weeds in rainfed wheat fields of Lorestan province, Iran, an indicator of the presence severity was defined. Presence Severity Index (PSI) indicates the portion of each field of the total contamination for a weed species in a given area. Data on grass weed species occurrence in rainfed wheat were collected in spring 2014 and 2015 from the 397 rainfed wheat fields throughout Lorestan province. Equations were fitted by Sigmaplot 12.3 and the ArcMap 10.1 software was used to drawing geographic weed maps. In drawing geographic weed maps, data grouped according to Jencks natural classification algorithm with minimal variance within groups and maximize variance between classes.
    Results And Discussion
    The optimum altitude for the presence of wild wheat and wild barley were estimated 1856 and 1703 m above sea level, respectively. The average altitude of wild wheat-infested wheat fields was significantly higher than the average altitude of wheat fields contaminated with wild barley. The range of altitude for the wild wheat presence in the wheat fields was form 1564 to 2169 m with an average of 1839 m above sea level. The range fo the wild barley presence in the wheat fields was from 885 to1982 m with an average of 1587 m above sea level. However, the range of altitude of all sampled wheat fields was form 697 to 2239 m above sea level. Generally wild wheat was not observed in all wheat fields of Poldokhtar, Kuhdasht and Doreh Chegeni. Among the 397 studied rainfed wheat fields in Lorestan, the highest level of presence severity index of wild wheat belonged to a wheat field in Vazlh village in the east of Khorramabad. The average wild wheat spike density of infected wheat fields was 42.1 spikes per square meter. Among the wild wheat-infected wheat fields, the highest spike density were belonged to the wheat fields in Khorramabad, Aligoudarz and Delfan, with a density of 54.7, 51.4 and 45.1 spikes per square meter, respectively. The north-east areas of Khorramabad and the east of Aligudarz and Delfan, with infested fields by presence severity index of more than 3%, were identified as the most important spots of this grass weed infestation in Lorestan province. Among the wild wheat-contaminated areas, the highest relative importance mean (44%) belonged to the Delfan, which showed the higher importance of wild wheat infestation compared to the other grass weeds in this area. The relative importance mean for wild wheat in Aligudarz, Selseleh, and Khorramabad were 34.6%, 34.2% and 20.6%, respectively. Wild barley was not found at all visited wheat fields in Azna and Aligoudarz. Based on the presence severity index, the contamination of wild barley in the wheat fields of Poldokhtar, Borujerd, Delfan and Doreh Chegeni also was not significant (the average of presence severity index of less than 1.0%). The highest level of presence severity index for wild barley (6.1) was observed for a wheat field in the Chaghalvandy area of Khorramabad. The average spike density of wild barley in wheat fields of Lorestan was 42 spikes per square meter. If we consider the average of 11 seeds per spike for wild barley, weed seed rain on the infected wheat fields of this province was estimated to 404 seeds per square meter. The presence severity index of wild barley for Khorramabad, Dorood, Kuhdasht, and Selseleh were 0.45%, 0.44%, 0.34%, and 0.28%, respectively. The highest level of wild barley relative importance index (50.7%) was belonged to Kuhdasht, which show the higher importance of wild barley compared to other grass weeds in this area. Wheat fields located in the northern of Khorramabad, the eastern areas of Kuhdasht, the central area of the Selseleh and Chegeni and the northeast areas of Delfan were identified as the main spots of wild barley infestation in the Lorestan province.
    Conclusions
    The Presence altitude domain for wild barley in rainfed wheat fields of Lorestan was 81.3% more than wild wheat that demonstrate the more possibility of wild barley invasion in a broader altitude scope.
    Keywords: Grass weeds, Infestation hotspots, Weed distribution
  • Hashem Aminpanah, Bijan Yaghoubi Pages 245-255
    Introduction
    Weeds are the major constraint on rice production. It has been reported that weeds cause rice yield losses by 30-40% in Bangladesh, 36 to 56% in the Philippines, 40 to 100% in South Korea and up to 90% in Iran. Extensive application of graminicides, flooding, and continuous hand weeding have increased the population of more problematic weed species like bulrush (Bolboschoenus maritimus (L.) Palla in rice fields of northern Iran. Bulrush is a perennial weed belongs to cyperaceae family and resistant to most paddy herbicides, flooding and also hand weeding. Yield reduction of rice was estimated up to 100% due to bulrush competition. Despite environmental concerns, theeffect of herbicides on non-target organisms, and the increase of herbicide-resistance weeds, chemical control is still the most commonly used and reliable method for weeds control in paddy rice production in Iran.
    Materials And Methods
    Field experiments were conducted at Rice Research Institute of Iran during 2013 and 2014, Rasht, (36° 54' N, 40° 50' E, -21 masl) to assess the efficacy of paddy herbicides for bulrush control. In the first experiment (2013), commonly used paddy herbicides in Iran including bensulfuron-methyl, butachlor, oxadiargyl, pretilachlor, and thiobencarb were evaluated for bulrush control. Two control treatments (hand weeded and weedy check) were also included for comparison. Based on the result of the first experiment, second experiment (2014) was designed to evaluate the efficacy of some new herbicides including flucetosulfuron, penoxulam, metsulforun-methyl, pyrazolate and also bensulfuron-methyl for bulrush control. Both experiments were conducted as randomized complete block design with three replications. Individual plots were 3m wide by 3m long and rice seedlings (cv. Hashemi) manually were transplanted on 23 May 2013 and 2014, with planting distance of 20cm × 25cm. Visual injury evaluation for rice (chlorosis, and growth stunting) and visual weed control (chlorosis, necrosis, and plant stand reduction) was conducted at 2, 4 and 6-WAT (a week after transplanting) in each plot. Visual ratings of rice toxicity and weed control were based on a scale of 0 to 100%, where 0 means no injury or no weed control and 100 means complete death or complete weed control. Also, bulrush biomass was determined at 2, 4 and 6- WAT in the first experiment and 4 and at 12-WAT in the second experiment from a randomly selected 1m2 quadrate in each plot. Weed samples were oven dried at 70 °C for 72 h and weighted. At the maturity stage, rice grain yield (based on 14% humidity), and rice biomass was determined from 5 and 1 m2 per plot, respectively. Rice biomass from each plot was dried at 75°C for 96 h and weighted. Harvest index was calculated by dividing the dry weight of the grain by the dry weight of aboveground (biological yield). Data were subjected to analysis of variance (ANOVA), and means were compared using Fisher's protected LSD test at the 0.05 probability level. All statistical analyses were conducted using SAS (ver. 9.1) software program.
    Results And Discussion
    Results of the first experiment showed excellent control of bulrush by bensulfuron-methyl (≥98) followed by pretilachlor (≥85%) at 6-WAT, at the end of critical weed control period in transplanting rice. The efficacy of other herbicides was ≤60%. The lowest biomass of bulrush was recorded for plots treated with bensulfuron-methyl (1.5 g m-2) and pretilachlor (10.6 g m-2). Results also showed that the highest grain yields were observed in plots treated with bensulfuron-methyl (4000 kg ha-1) or pretilachlor (4231 kg ha-1). This was mainly due to optimum weed control in these plots. Grain yield in weedy plots reduced by 76% compared to hand weeded plots, indicating the severe infestation of the plots to bulrush and the ability of this weed to cause rice yield loss. The reduction in grain yield in weedy plots could be mainly due to severe competition for nutrient, especially nitrogen, and light. Because of adequate moisture in paddy fields, reduction in rice growth due to weed-crop competition for water is negligible. The highest harvest indices were observed in plots treated with pretilachlor (52.4%) and butachlor (50%) and weed-free plots (48.8%), while the lowest one was recorded for weedy plots. This result indicates that assimilate partitioning to grain or photosynthesis is reduced under weedy condition. The result of the second experiment also confirmed the result of the first one and indicated that bensulfuron-methyl had good efficacy (≥85%) on bulrush control. The result also indicated that bulrush was controlled very well by flucetosulfuron (88%) and pyrazolate (85%). In contrast, penoxulam and metsulforun-methyl had fair efficacy (≤ 49%) on bulrush control. Moreover, flucetosulfuron, and pyrazolate showed good compatibility with rice, and grain yield in these treatments did not statistically differ with gain yield in plots treated with thiobencarb bensulfuron-methyl. Grain yield was significantly lower in weed-free plot compared to plots treated with bensulfuron-methyl, flucetosulfuron, and pyrazolate. This may be due to that manual weeding can be performed only when weeds have reached a sufficient size to be pulled out easily by hand. By that time, yield losses may have already occurred. At the same time, it seems that weed control by 2- or 3-times hand weeding induced severe stress on rice plant, resulted in a decrease in grain yield. Grain yield in a weedy plot was reduced by 51 and 62% compared with weed-free plots and with plots treated with thiobencarb bensulfuron-methyl, respectively. These results indicate the importance of bulrush control in paddy fields.
    Conclusion
    Of the current paddy registered herbicides in Iran, bensulfuron-methyl was the most effective herbicide for bulrush control followed by pretilachlor with partial efficacy on bulrush. Newly investigated herbicides, flucetosulfuron, and pyrazolate, could be registered as good options for bulrush control in paddy rice. In respect to the different mechanism of action of new herbicides and their compatibility with rice, the alternative application of new and current herbicide is recommended for controlling bulrush and delaying weed resistance to the herbicide.
    Keywords: Chemical control, Rice, Weed, Yield loss
  • Nosrat Allah Karimi Arpanahi, Seyed Vahid Eslami, Rahmat Allah Dehghan Khalili, Mohammad Javad Babaie Zarch Pages 257-267
    Introduction
    Salinity is one of the most important abiotic stresses that cause severe effects on crop production around the world. Estimates indicate that more than 800 million hectares of arable lands in the world are affected by salinity. Salinity impacts on various aspects of growth from germination to seed production in plants. Plants′ responses to salinity, however, are different and depend on the toxicity, osmotic potential, as well as the stress duration. Purple nutsedge (Cyperus rotundus L.) is one of the noxious weeds. This weed belongs to sedge family, and is a C4 perennial plant which reproduce by sexual (seeds) and asexual (tubers and rhizomes) means. It can cause tremendous damage on summer crop fields such as onion, potato, maize, sunflower, and so on. Evaluation of weed growth responses to saline condition came about by water and soil can provide for us very important information by which we choose appropriate weed control strategies. Since a few experiments have been evaluated growth characteristics of purple nutsedge under salinity stress, this study was conducted to evaluate the salinity effects on growth characteristics of purple nutsedge.
    Material and
    Methods
    To evaluate the effect of irrigation water and soil salinity on growth characteristics of purple nutsedge, two separate experiments were conducted in a randomized complete block design with three replications in the greenhouse of Faculty of Agriculture at University of Birjand in 2013. The first experiment contained five salinity levels of water including 0, 3, 5, 7 and 9 dS.m-1 and in the second experiment, there were five salinity levels of soil including 1, 3, 5, 7 and 9 dS.m-1. The salinity levels of water were prepared through solving a certain amount of NaCl in water based on this equation: NaCl (mg. L-1) =EC (dS.m-1)×640.. Following determination of soil electrical conductivity, soil salinity levels were prepared by adding NaCl to the soil based on saturation moisture percent and field capacity. A tuber of purple nutsedge was planted at 2.5 cm depth in each pot. Experiments were terminated at the end of the vegetative growth stage of purple nutsedge (105 days after emergence). Measured traits were plant height, stem number per pot, leaf area, and tuber number per pot, shoot and underground dry weight. After collecting the data, ANOVA was performed using Genstat Ver. 9 and mean comparisons were performed using Fisher's least significant difference test at 5% significant level. In order to evaluate purple nutsedge growth response to salinity stress, an exponential decay model was used; Y=a*exp(-b*x), thta in this model, a and b represents the maximum amount of studied traits and the slope of curve according to the model estimation, respectively.
    Results And Discussion
    The results of both experiments showed that the growth characteristics of purple nutsedge (plant height, stem number per pot, leaf area, tubers number per pot, shoot and underground dry weight) were significantly affected under soil (P
    Keywords: Sexual, asexual reproduction, Soil electrical conductivity, Vegetative growth
  • Ali Shayanfar, Farshid Ghaderifar, Rahmatollah Behmaram, Afshin Soltani, Hamidreza Sadeghipour Pages 269-278
    Introduction
    Rapeseeds are susceptible to shuttering during harvest increasing soil seed bank. Secondary dormancy is induced in shuttered seeds due to dryness and darkness conditions of soil in summer season and its level is different based on the seed types. Germination may be observed in seeds with low level of secondary dormancy. Before initiation of the next growing season and under undesirable environmental conditions seedlings will die. In contrast, high level of secondary dormancy in the other seeds is not eliminated and then they will emerge in the next growing season along with the crops as rapeseed volunteers. Rapeseed volunteers are considered as weeds in the next growing season and transfer target genes from crops to relative plants and weeds during pollination causing a decrease in quality, yield, and eventually purity of produced seeds.
    Materials And Methods
    Six rapeseeds cultivars and lines were selected with different secondary dormancy levels of low (Gor-o-16 and Gor-H-4), medium (Zarfam and RGS003), and high (Gor-o-4 and Gor-o-6) among 46 lines and/or cultivars of the previous study. Three replications of different seeds were placed in incubator at 20°C in darkness before induction of secondary dormancy (primarily secondary dormancy was determined). In fact, three replications of seeds with different levels of secondary dormancy were first exposed to inducing condition of secondary dormancy (-15 bar potential for 14 days) and then exposed to different treatments of temperature and light i.e. 20°C (darkness), 20°C (light), 25°C (darkness), 25°C (light), 30°C (darkness), 30°C (light), 3-30°C (darkness,12/12hours), 3-30°C (darkness/light (12/12 hours)), 20-30°C (darkness, 12/12 hours) and 20-30°C (darkness/light (12/12 hours)). Finally, secondary dormancy responses were analyzed.
    Result and
    Discussion
    Average primary germination in all seeds including cultivars and lines of rapeseeds before secondary dormancy induction was higher than 98% implying the absence of primary dormancy. After secondary dormancy induction, the highest germination was shown in the seeds with low level of seeds secondary dormancy at constant temperature in darkness and light. It was decreased in those with medium level of secondary dormancy by increasing temperature from 20 to 30°C in darkness, even though decreasing process was higher in light treatment. But it was the same in the seeds with secondary dormancy in comparison with medium levels of secondary dormancy in darkness and light. High level of secondary dormancy in G-O-6 and G-O-4 can be attributed to their responses to increased temperature and the light, respectively. Secondary dormancy was eliminated in seeds with high level of secondary dormancy by being exposed to 3-30°C treatment in darkness that implied replacement of alternative temperature with light requirement. Secondary dormancy was not completely eliminated for 20-30°C and 30°C treatments as some parts of seed population need alternative temperature and the others require light for complete elimination. Some studies suggested that light is required for complete elimination of secondary dormancy as it influences hormonal balance indirectly through phytochromic pathways. Moreover, the other studies reported that secondary dormancy can be partially eliminated by impacting heat shock proteins and light requirement. Rapeseeds appear to be photoblastic after inducing secondary dormancy. Further studies are required on the roles of phytochromes and hormonal balance pathways of ABA and GA in eliminating secondary dormancy of rapeseeds.
    Conclusion
    Different rapeseed responses with different levels of secondary dormancy after being placed in soil seed bank were simulated by laboratory conditions with emphasis on two environmental factors of temperature and light. The same response was shown by increasing constant temperature in rapeseed with different levels of secondary dormancy. Decrease in secondary dormancy was obvious in them and a greater increase was found for mentioned treatment in light. Secondary dormancy in all seeds was entirely eliminated after being exposed to alternative temperature and light. Complete elimination of secondary dormancy was observed in response to 3-30°C alternative temperature whether in darkness or darkness/light conditions. It was found that light requirement can be removed after induction of secondary dormancy by 3-30°C alternative temperature in darkness. However, secondary dormancy was only eliminated in some parts of seed population by 20-30°C and 30°C. In addition, light was observed as a critical factor for breaking for the others. It can be thus concluded that light was required for eliminating secondary dormancy in rapeseeds and seeds became photoblastic after the induction. Therefore, secondary dormancy can be removed before next growing season by being exposed to mentioned temperature and light.
    Keywords: Phytochrome, Soil seed bank, Weed
  • Adel Modhej, A. Kaihani Pages 279-287
    Introduction
    Maize is among the world's three most important cereal crops. Weeds are one of the most important factors that reduce maize production. They cause important yield losses worldwide with an average of 12.8% despite weed control applications and 29.2% in the case of no weed control. Weeds compete with crops when they remove a portion of a resource from a shared resource pool, leaving the crop with less of the resource than is needed for optimum growth. Competition may occur for water, creating or exacerbating water stress. It may occur for nutrients such as nitrogen, leading to chlorosis, leaf senescence and yield loss. Increasing the ability of a crop to compete with weeds has been considered an approach to improving weed management in recent years. The importance of weed competition in maize depends on the maize genotype, weed species, crop growth stage, the weed density, the level of water, and nutrient stress. Some crops can significantly suppress weeds by their ability to grow faster than weeds or to endure greater sowing densities. The plant competitive ability can be expressed in the following two modes: First, the crop weed suppressive ability (WSA) that results in the reduction of weed biomass and second, the crop tolerance ability (CTA) to tolerate weed effects and to have high yields at the same time. Crop tolerance to weed interference aims to improve stability of yield and quality in weedy fields, whereas weed-suppressive ability targets the long-term management of weed populations by reducing seedbank size. Several traits, including the growth intensity in the initial developmental stages, rapid development of a high leaf structure, the plant height, maximum LAI, rate of canopy closure, height of LAI, and leaf architecture, may improve weed-suppressive ability and dent maize tolerance to weed interference. Therefore, the objective of this experiment was to evaluating the competitive ability of maize (Zea mays L.) genotypes against weeds under different nitrogen rates.
    Materials And Methods
    Experiments were carried out on clay loam soil with low organic matter content (less than 1%) and a pH of 2.9 at south west Iran in 2011-2012 growing season. The experiment site had a hot climate with a moderate winter and dry and hot summer. Treatments consisted of a split-plot with randomized complete blocks design and three replicates. Nitrogen rates (0, 90, 180 and 260 kgNha-1) were the main plots and four dent maize hybrids Sc.704, DKC6589, Mobeen and Sc.640 were planted in sub-plots. DKC6589, Mobeen and Sc.640 are an early-season hybrids, whereas Sc.704 is relatively late-season hybrid. Plots consisted of 6 maize rows (distance between and within the rows 75 and 18 cm, respectively) and 6 m long. Maize hybrids were sown on 1st Jun. Fields received 100 kgPha-1 and 150 kg K ha-1. The P and K were supplied in the form of single superphosphate and potassium sulfate, respectively. Nitrogen treatments were applied in two equal splits as urea (46% N) at two and six weeks after planting by side placement. Each plot was divided into two parts hypothetical. One part was maintained weed-free and another weedy for the all maize duration growth stages. In weed-free parts, weed removal was started immediately after crop emergence and the plots were kept weed-free for different growth stage durations until physiological maturity of maize. The experiment was properly monitored and irrigated whenever water was needed. Weed plants were harvested at the R1 (silking) growth stage of maize using 0.5×0.5m quadrate, and weed biomass obtained by drying tissues at 68 C to constant mass. Weed density and species also, determined. Interference of maize and weed was quantified by calculating weed index (WI), weed interference tolerance index (WITI) and competition index (CI(. Statistical analysis was made using the SAS statistical software. Differences between traits means were assessed using Duncan's Multiple Range Test.
    Results And Discussion
    The percent loss of grain yield, 100 grain weight, biological yield and grain number per rows under weed interference conditions were 21.7, 5.3, 24 and 10%, respectively. Grain yield reduction in weedy plots was resulted from decreasing grain number per rows and biological yield. Negative impact of weeds on maize yield was enhanced under higher rates of nitrogen. When maize competed with weeds, the reduction of grain yield at 260 kg N ha-1 treatment was more compared to 180 kg N ha-1maize. Maize genotypes were different in response to weed competition. The highest weed tolerance interference index was obtained in DKC6589 line due to higher grain yield in both weedy and weed-free plots. Competition index was higher in Sc. 704 and DKC6589 than other genotypes. Although Mobeen and Sc.640 hybrids had lower grain yield reduction trend under weed competition conditions, but DKC6589 and Sc.704 showed a high grain yield potential and high ability to withstand weed competition.
    Keywords: Competition indices, Genotypes, Weed interference
  • Seadeh Maryam Mozafari, Hamidreza Mohamadduost, Hamid Reza Nikkheh Pages 289-297
    Introduction
    Weeds are an important challenge to crop production, particularly in sustainable agriculture. Today, identification of highly competitive cultivars is an easy and inexpensive method for weed management in sustainable agriculture systems. Watson et al. in their study of 29 barley varieties found that yield loss due to weed competition varied from 6 to 79 percent, which is related to their ability to compete. In the case of wheat, for more than four decades, the difference of the weed competitive ability between wheat cultivars has been investigated. Two aspects of cultivar competitiveness can be defined, competitive index (CI) and weed interference tolerance index (WITI). CI is the ability of a cultivar to reduce weed growth and WITI is the ability of a cultivar to achieve high yield despite weed competition. These traits differ based on genetical and agronomical aspects. CI is often associated with traits including vigorous growth, allelopathic potential, crop cover, and height and leaf area. Although for environmental stresses high tolerance indexes are important, the competitive index is more important in the long-term management of weed management. Trusting the tolerance index alone can lead to a sharp increase in the weed seed bank, which may not tolerate high-tolerance cultivars. So, the present study was carried out to classify Iranian wheat cultivars based on traits related to competition and tolerance indices and to determine the correlation between indices with yield and yield components.
    Material and
    Methods
    This experiment was conducted to classify Iranian wheat cultivars based on traits related to competition and tolerance indices and to determine the correlation between indices with yield and yield components in the agricultural research farm of the faculty of agriculture and natural resources, University of Mohaghegh Ardabili at 2015-2016 growing season. For this purpose, 25 wheat cultivars were tilled in November 2015 under with or without weed competition. In each plot, 10 wheat lines were cultivated at a distance of 20 cm and a length of 5 m. The experiment was conducted in a randomized complete block design with three replications. At the beginning of spring, from each plot, a sample of wheat plants was harvested at a surface area of 0.25 m2, dried at 75 ° C for 48 hours in order to measure the initial dry weight of the cultivars. Sampling from weeds was conducted before the end of growing season. Wheat plants harvested at maturity stage from 1 m2 and seed yield was reordered. To determine the yield loss, CI and WITI was used appropriate formulas.
    Results And Discussion
    The results showed that there was no significant correlation between weed density with growth traits of wheat cultivars, while there was a significant negative correlation between weed dry weight and these traits. The highest correlation was found between the primary cover with dry weeds weight (R2= -0.70; P
    Keywords: Competitive index, Cultivars, Health produce, Integrated weed management
  • Akbar Aliverdi Pages 299-306
    Introduction
    Although “the pesticides are a global human rights concern” (24), they can secure global food security provided that the rational herbicide application technique is taken into consideration (7). The principal elements of rational herbicide application technique include the selectivity of herbicide, the application of appropriately timed herbicide and the accuracy of application equipment (4). The hydraulic spray nozzle atomizes the spray solution into droplets (9). Thus, it is a key component to influence on the accuracy of spraying (17). The nozzle technology is always improving, resulting in the introduction of more than 60 nozzle types that all are available to apply in different situations. High nozzle diversity can cause some difficult to select a proper nozzle, particularly when wind speed at time of application is authorized or unauthorized for spraying. The present study aims to compare 14 nozzle types in relation to the efficacy of sethoxydim to control winter wild oat at two wind speeds.
    Materials And Methods
    The seeds of winter wild oat (Avena sterilis ssp. ludoviciana) were treated to germinate (2). Then, the 9 seedlings were planted within each pot and grown in the Research Greenhouse of Bu-Ali Sina University, Hamedan, Iran and thinned to 6 plant pot-1 at the one-leaf stage. At the five-leaf stage, they were treated with 0, 23.5, 47, 94, 187.5, and 375 g sethoxydim ha-1 using 14 nozzle types at two wind speeds of 0.5 and 9.5 m s-1 in outdoor conditions. A standard 210 L ha-1 carrier volume was sprayed at a pressure of 3 bar with the 11002 yellow nozzles of Twin Fan Standard (TFS), Fan Low Drift (FLD), Standard Flat Fan (SFF), Turbo Wide Angle Flat (TWAF), Low Pressure Air Induction Twin Flat (LPAITF), Low Pressure Air Induction Flat (LPAIF), Compact Fan Air (CFA), Compact Fan Air-Tilt (CFA-T), Turbo Twin Flat (TTF), Air Induction Twin Fan 3070 (AITF3070), Twin Fan Low Drift (TFLD), Air Induction Turbo Twin Flat (AITTF), Twin Fan Air (TFA), Turbo Air Induction Flat (TAIF). Four weeks after spraying, the dry weight of plants were obtained and the date were fitted to analyze using a four-parameter log-logistic model to estimate the Effective Doses (ED) (19).
    Results And Discussion
    The ED10, 50 and 90 values of sethoxydim on the control of winter wild oat were affected significantly by nozzle type or wind speed. When spraying was done at 0.5 m s-1 wind speed, the lowest and the highest ED50 values were obtained with the TFS and TAIF nozzles, requiring 12.81 and 62.72 g sethoxydim ha-1 to give a 50% reduction in dry weight of winter wild oat, respectively. In such a situation of wind speed, the ranking of the nozzle types based on the sethoxydim dose required to give a 50% reduction in dry weight of winter wild oat was TAIF > TFA > LPAIF > TFLD > LPAITF > AITTF > CFA > CFA-T > FLD > TTF > TWAF > AITF3070 > SFF > TFS (Table 1). It can be concluded that the endo-drift by TFS nozzle at low wind speed is lower than other nozzles. When spraying was done at 9.5 m s-1 wind speed, the lowest and the highest ED50 values were obtained with the AITF3070 and TFS nozzles, requiring 45.13 and 87.35 g sethoxydim ha-1 to give a 50% reduction in dry weight of winter wild oat, respectively. In such a situation of wind speed, the ranking of the nozzle types based on the sethoxydim dose required to give a 50% reduction in dry weight of winter wild oat was TFS > FLD > TAIF > TFA > SFF > CFA-T > TWAF > LPAIF > TFLD > AITTF > CFA > TTF > LPAITF > AITF3070. It can be concluded that the exo-drift by TFS nozzle at high wind speed is higher than other nozzles. It seems that a limiting factor for the performance of nozzles categorized as VC to UC at high wind speed can be the spray carrier volume.
    Conclusions
    As a proper nozzle to spray sethoxydim with 210 L carrier volume ha-1 at a pressure of 3 bar to control winter wild oat at low and high wind speed, the TFS and AITF3070 nozzles can be applied to obtain an optimal herbicide efficacy, respectively.
    Keywords: Drift, Dose, response, Dual flat, Herbicide, Single flat