فهرست مطالب

پژوهشهای زراعی ایران - سال سیزدهم شماره 3 (پیاپی 49، 1394)
  • سال سیزدهم شماره 3 (پیاپی 49، 1394)
  • بهای روی جلد: 5,000ريال
  • تاریخ انتشار: 1394/09/06
  • تعداد عناوین: 16
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  • پرویز رضوانی مقدم، محمد بهزاد امیری، علی نوروزیان، حمیدرضا احیایی صفحات 435-447
    در سال های اخیر همواره استفاده از نهاده های بیولوژیک به عنوان یکی از راهکارهای اساسی در جهت توسعه پایدار محصولات زراعی و به ویژه گیاهان دارویی مطرح بوده اند. به منظور بررسی اثر گونه های مختلف میکوریزا و کود زیستی نیتروکسین بر عملکرد و اجزای عملکرد سیر آزمایشی در سال زراعی 89-1388 در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد، به صورت فاکتوریل در قالب طرح پایه بلوک های کامل تصادفی و با سه تکرار انجام شد. عوامل مورد بررسی شامل گونه های مختلف میکوریزا (Glomus mosseae، Glomus intraradices و شاهد بدون میکوریزا) و کود زیستی (کاربرد و عدم کاربرد نیتروکسین (دارای باکتری های Azotobacter sp. و Azospirillum sp.)) بودند. نتایج آزمایش نشان داد که تلقیح با دو گونه میکوریزا صفات مورد مطالعه را نسبت به شاهد افزایش دادند. وزن سوخ در بوته به طور معنی داری تحت تاثیر گونه های مختلف میکوریزا قرار گرفت، به طوری که گونه های Glomus mosseae و Glomus intraradices وزن سوخ در بوته را به ترتیب 48 و 29 درصد نسبت به شاهد افزایش دادند. تلقیح با نیتروکسین به طور معنی داری بر طول و قطر سوخک تاثیر داشت، به طوری که به ترتیب باعث افزایش 13 و 8 درصدی طول و قطر سوخک نسبت به شاهد شد. با توجه به نتایج آزمایش، تلقیح با Glomus mosseae در تلقیح و عدم تلقیح با نیتروکسین، در اکثر صفات مورد مطالعه نسبت به سایر تیمارها برتر بود. اثر متقابل تلقیح نیتروکسین و گونه های مختلف میکوریزا بر تمامی صفات مورد مطالعه معنی دار بود. نیتروکسین اثر تمامی گونه های میکوریزای مورد مطالعه را در مقایسه با شرایطی که این میکوریزاها به تنهایی به کار رفتند تشدید کرد. بیشترین (4306 کیلوگرم در هکتار) و کمترین (1665 کیلوگرم در هکتار) عملکرد اقتصادی به ترتیب در تیمارهای تلقیح Glomus mosseae توام با تلقیح نیتروکسین و عدم میکوریزا + عدم تلقیح نیتروکسین به دست آمد. به طور کلی با توجه به یافته های این پژوهش، به نظر می رسد می توان با استفاده از نهاده های بیولوژیک ضمن کاهش مصرف کودهای شیمیایی و مخاطرات زیست محیطی ناشی از آنها، پایداری تولید را در درازمدت حفظ نمود.
    کلیدواژگان: حجم سوخ، عملکرد زیستی، عملکرد سوخ، کود بیولوژیک
  • علیرضا کوچکی، سارا بخشائی، سرور خرم دل، ویدا مختاری، شهربانو طاهرآبادی صفحات 448-460
    به منظور بررسی تاثیر تلقیح با دو گونه قارچ میکوریزا بر عملکرد، اجزای عملکرد و کارایی مصرف آب گیاه دانه کنجد (Sesamum indicum L.)، آزمایشی در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد در دو سال زراعی 89-1388 و 90-1389 به صورت اسپلیت پلات در قالب طرح بلوک های کامل تصادفی با سه تکرار انجام شد. کرت اصلی سه سطح آبیاری شامل 2000، 3000 و 4000 متر مکعب آبیاری در هکتار و کرت های فرعی تلقیح با دو گونه قارچ میکوریزا شامل Glomus mosseae و G. intraradices و شاهد بود. نتایج نشان داد که اثر سطوح آبیاری بر تمام اجزای عملکرد به جز وزن هزار دانه، عملکرد بیولوژیک و دانه، شاخص برداشت و کارایی مصرف آب براساس عملکرد بیولوژیک و دانه معنی دار (p≤0.05) بود. با افزایش مقدار آبیاری از 2000 به 4000 متر مکعب در هکتار عملکرد بیولوژیک و دانه به ترتیب برابر با 52 و 118 درصد بهبود یافت. افزایش مقدار آبیاری از 2000 به 4000 متر مکعب در هکتار بهبود 22 درصدی کارایی مصرف آب کنجد براساس عملکرد دانه را موجب شد. تلقیح با گونه های میکوریزا اجزای عملکرد، عملکرد بیولوژیک و دانه، شاخص برداشت و کارایی مصرف آب کنجد براساس عملکرد بیولوژیک و دانه را به طور معنی داری تحت تاثیر قرار داد (p≤0.05). تلقیح باG. mosseae عملکرد دانه را به ترتیب برابر با 7 و 12 درصد در مقایسه با G. intraradices و شاهد بهبود بخشید. میزان این بهبود برای کارایی مصرف آب براساس عملکرد دانه به ترتیب برابر با 7 و 24 درصد بود. تلقیح با میکوریزا با بهبود توسعه سیستم ریشه ای و در نتیجه افزایش فراهمی رطوبت و دسترسی به عناصر غذایی موجب بهبود کارایی مصرف آب گردیده است که این تاثیر برای گونه G. mosseae بالاتر از گونه G. intraradices بود.
    کلیدواژگان: توسعه سیستم ریشه ای، دانه روغنی، کشاورزی پایدار، همزیستی میکوریزایی
  • حمید وحیدی، غلامرضا خواجویی نژاد، عباس رضایی استخروئیه صفحات 461-470
    برای مقابله با کمبود آب آبیاری، دستیابی به ارقام متحمل به کم آبی گیاهان ضروری است. به منظور بررسی تاثیر کم آبیاری بر عملکرد و اجزاء عملکرد پنج رقم سورگوم، در بهار 1390 تحقیقی انجام شد. این تحقیق در مزرعه دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، به صورت کرت های خرد شده در قالب طرح بلوک های کامل تصادفی و در سه تکرار اجرا گردید. کرت های اصلی شامل سه رژیم آبیاری، I1، I2 و I3 به ترتیب آبیاری پس از تبخیر 50، 80 و 110 میلی متر از تشت کلاس A و کرت های فرعی شامل پنج رقم سورگوم به نام های اسپیدفید، پگاه، پیام، سپیده و کیمیا بودند. جهت تعیین نیاز آبی گیاه از لایسیمتر زهکش دار استفاده گردید. نتایج نشان داد رژیم های مختلف آبیاری بر عملکرد دانه ارقام سورگوم تاثیر معنی داری نداشتند. عملکرد دانه، در رقم سپیده بالاترین مقدار (7806 کیلوگرم در هکتار) و در رقم پیام کمترین مقدار (4721/9 کیلوگرم در هکتار) را دارا بود. رقم پگاه با 30365 کیلوگرم در هکتار بیشترین عملکرد بیولوژیک و رقم پیام با 12865 کیلوگرم در هکتار کمترین عملکرد بیولوژیک را به خود اختصاص دادند. بالاترین کارآیی مصرف آب عملکرد دانه و بیولوژیک به ترتیب 1/12 و 4/34 کیلوگرم بر متر مکعب آب، در رقم های سپیده و پگاه به دست آمد. حداقل نیاز آبی عملکرد دانه و بیولوژیک به ترتیب برابر با 0/91 و 0/29 متر مکعب آب بر کیلوگرم برای ارقام سپیده و اسپیدفید به دست آمد. در مجموع رقم سپیده مناسب ترین رقم برای تولید دانه در منطقه کرمان شناخته شد.
    کلیدواژگان: تبخیر، تعرق، تنش خشکی، شاخص برداشت، کم آبیاری، نیازآبی گیاه
  • سمانه حبیبی، موسی مسکر باشی، معصومه فرزانه صفحات 471-484
    باتوجه به کاهش کیفیت آب به دلیل شور شدن منابع آبی در اثر خشک سالی به عنوان یک عامل محدودکننده در تولید، مقابله با آثار مخرب آن به روش های مختلف مانند کاربرد قارچ های میکوریزا حائز اهمیت است. به منظور بررسی تاثیر قارچ های میکوریزا بر عملکرد و اجزای عملکرد گیاه گندم یک آزمایش گلدانی در گلخانه تحقیقاتی دانشگاه شهید چمران اهواز به صورت اسپلیت فاکتوریل در قالب طرح بلوک های کامل تصادفی در سه تکرار انجام شد. فاکتورهای آزمایش شده عبارت بودند از فاکتور اصلی شامل شوری آب (کیفیت آب) در چهار سطح آب تصفیه (EC ≥ 1 dS m-1)، آب شهری (EC = 1/7-3 ds m-1)، آب شهری همراه نمک و آب تصفیه همراه نمک (EC = 8 ds m-1) و دو فاکتور استریلیزاسیون خاک شامل خاک استریل و خاک غیر استریل و فاکتور تلقیح با قارچ های میکوریزا با سه گونه e Glomusmossea، G. intraradices، G. geosporum، مخلوط سه گونه قارچ و شاهد (عاری از قارچ) به صورت فاکتوریل در کرت های فرعی اعمال شد. از اجزای عملکرد و عملکرد در مرحله رسیدگی و از درصد کلونیزاسیون ریشه در مرحله گل دهی اندازه گیری به عمل آمد. نتایج نشان داد که اعمال شوری درصد کلونیزاسیون ریشه و تعداد دانه در سنبله را کاهش داد ولی بر عملکرد و دیگر اجزای عملکرد اثر معنی داری نداشت. تیمار خاک غیر استریل که شامل دیگر میکروارگانیسم ها نظیر قارچ های بومی خاک نیز بود با وجود افزایش درصد کلونیزاسیون ریشه سبب تغییرات معنی داری در عملکرد و اجزای عملکرد نشد. تلقیح با سه گونه قارچ میکوریزا موفقیت آمیز بوده و در میان تیمارهای تلقیح قارچ، به طور میانگین 15 تا 32 درصد کلونیزاسیون و 7 تا 13 درصد وابستگی میکوریزایی مشاهده شد و سبب افزایش معنی دار عملکرد دانه، تعداد سنبله و تعداد دانه در بوته شد. علاوه بر درصد کلونیزاسیون در تمامی اجزای عملکرد به جز تعداد سنبله در بوته برهمکنش شوری و قارچ میکوریزا معنی دار شد. در میان اجزای عملکرد برهمکنش استریلیزاسیون خاک و قارچ میکوریزا تنها بر سنبله در بوته و تعداد دانه در سنبله و درصد کلونیزاسیون معنی دار شد. همبستگی مثبت و معنی داری بین درصد کلونیزاسیون با تعداد سنبله، تعداد دانه در بوته و عملکرد دانه وجود داشت.
    کلیدواژگان: درصد کلونیزاسیون ریشه، شوری، قارچ های بومی، وابستگی میکوریزایی
  • علی سپهری، مریم صمدی صفحات 485-495
    به منظور بررسی اثر تراکم های مختلف بوته و کاربرد توام کودهای شیمیایی و زیستی بر شاخص های رشدی و عملکرد موسیلاژ در گیاه دارویی اسفرزه، آزمایشی مزرعه ای در سال زراعی 91- 1390 در شرایط آب و هوایی همدان به صورت فاکتوریل، در قالب طرح بلوک های کامل تصادفی در سه تکرار اجرا گردید. از سه تراکم 70، 100 و 130 بوته در متر مربع و سطوح کودی 100 درصد کود شیمیایی (شاهد)، 50 درصد کود شیمیایی + کود زیستی نیتروکسین و بیوفسفر، 25 درصد کود شیمیایی + کود زیستی نیتروکسین و بیو فسفر استفاده شد. نتایج تجزیه داده ها نشان داد که برهمکنش سطوح مختلف تیمارهای مختلف تراکم و کود بر صفات ارتفاع بوته، تعداد ساقه فرعی، حداکثر شاخص سطح برگ، حداکثر سرعت رشد محصول، حداکثر تجمع ماده خشک و عملکرد موسیلاژ معنی دار بود. بیشترین عملکرد موسیلاژ و حداکثر تجمع ماده خشک به ترتیب معادل 17/39 گرم در مترمربع و 497/56 گرم در مترمربع در تراکم 130 بوته در متر مربع با مصرف توام 50 درصد کود شیمیایی + کود زیستی به دست آمد. در تراکم 130 بوته در متر مربع بین تیمار 100 درصد کود شیمیایی و کود تلفیقی 50 درصد شیمیایی + کود زیستی در صفات مورد بررسی تفاوتی وجود نداشت. کمترین مقدار عملکرد موسیلاژ در تراکم 70 بوته در متر مربع به همراه مصرف 25 درصد کود شیمیایی + زیستی حاصل شد. بنابراین تیمار کود تلفیقی 50 درصد شیمیایی + کود زیستی نیتروکسین و بیوفسفر و تراکم 130 بوته در مترمربع برای شرایط آب و هوایی همدان قابل توصیه است.
    کلیدواژگان: بیوفسفر، حداکثر سرعت رشد محصول، حداکثر شاخص سطح برگ، نیتروکسین
  • سید یوسف موسوی طغانی، پرویز رضوانی مقدم، مهدی نصیری محلاتی، محمدرضا دماوندیان صفحات 496-512
    به منظور ارزیابی تنوع گونه ای، ساختاری و کارکردی علف های هرز بوم نظام های برنج استان مازندران، مطالعه ای طی سال زراعی91-1390 در شهرستان های بابل و بابلسر اجرا گردید. نمونه های تصادفی از 9 کوآدرات 1متر×1متر مزارع دو بوم نظام برنج تحت مدیریت ارگانیک و رایج، طی چهار مرحله (پنجه زنی، ساقه روی، پرشدن دانه و پس از برداشت) به دست آمد. میزان تنوع، یکنواختی، فراوانی و تشابه علف های هرز، به تفکیک جنس و گونه تعیین گردید. تجزیه داده ها با استفاده از آزمون t و گروه بندی از طریق تجزیه خوشه ایبه روش سلسله مراتبی انجام گردید. میانگین شاخص های تنوع در نظام رایج، طی دو مرحله پنجه زنی و ساقه روی، بیشتر از نظام ارگانیک و طی مراحل پرشدن دانه و پس از برداشت، کمتر از آن بود. براساس هر دو شاخص تنوع سیمپسون و شانون-واینر، در سطح تشابه 76 درصد، دو خوشه تشکیل گردید. مبتنی بر شاخص های یکنواختی کامارگو و اسمیت-ویلسون، به ترتیب در سطح تشابه 83 و 82 درصد، دو خوشه ایجاد شد. دامنه شاخص تشابه از 1/89 تا 83/96 درصد متغیر بود. در مجموع گروه بندی علف های هرز، براساس فراوانی نسبی، طی مراحل مختلف نمونه برداری، حاکی از وجود دو خوشه در سطح 78 درصد و چهار خوشه در سطح تشابه حدود 85 درصد بود. در گروه بندی مراحل نمونه برداری براساس تراکم کلیه علف های هرز، دو خوشه در سطح تشابه 39 درصد به دست آمد. مبتنی بر نتایج حاصل از این تحقیق، تعداد کل علف های هرز نمونه گیری شده در مزارع دو بوم نظام رایج و ارگانیک برنج، شامل 10 گونه از 8 جنس 4 خانواده بود. در این میان به تناسب شکل رویش، 75 درصد خانواده ها تک لپه و 25 درصد آن ها دولپه بودند. خانواده گندمیان با سه گونه متنوع ترین خانواده علف های هرز تک لپه و C4 بودند، همچنین دو علف هرز سمج از چهار گونه دارای خصوصیت مربوط، متعلق به خانواده گندمیان بودند. خانواده جگن ها، دو گونه از چهار گونه چند ساله را به خود اختصاص دادند. علف های هرز خانواده گندمیان و جگن ها، حدود 70 درصد علف های هرز موجود در دو بوم نظام را شامل شدند. این مطالعه نشان داد که ساختار و کارکرد علف های هرز، تحت تاثیر نظام های مدیریتی متفاوت بود.
    کلیدواژگان: تراکم، خوشه بندی، شاخص سیمپسون، شاخص کامارگو، فراوانی
  • رضا اعظمی، محمدرضا اردکانی، مسعود گماریان صفحات 513-523
    به منظور بررسی اثرات تلقیح دو اکوتیپ شبدر ایرانی با سویه های مختلف باکتری Rhizobium leguminosarum biovar trifoli توام با باکتری افزایش دهنده رشد PGPR) Pseudomonas putida) بر روی برخی از خصوصیات کمی و کیفی دو اکوتیپ شبدر ایرانی، آزمایشی به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در ایستگاه تحقیقات کشاورزی و دامپروری شهرستان گلپایگان در سال زراعی90- 1389 انجام شد. عوامل اصلی این آزمایش عبارت بودند از دو اکوتیپ محلی شبدر ایرانی به نام هفت چین اصفهان (V2) و هفت چین مرکزی (V1) و عوامل فرعی شامل دو سویه باکتری ریزوبیوم Rb-13) و(Rb-3، و یک سویه باکتری سودوموناس پوتیدا (PS-168) و در کل چهار چین برداشت شد. نتایج حاصل از این تحقیق نشان داد که تلقیح با باکتری های ریزوبیوم و سودوموناس تاثیر معنی داری بر روی شاخص های کمی رشد داشت و باعث افزایش عملکرد علوفه تر و خشک، افزایش ارتفاع ساقه، افزایش میزان نسبت برگ به ساقه و تعداد غدد تشکیل شده بر روی ریشه شدند، اما تاثیری بر روی صفات کیفی و صفت کمی عمق نفوذ ریشه نداشت. باکتری افزایش دهنده رشد (PGPR) منجر به افزایش صفات کمی رشد شد. همچنین در غالب موارد تلقیح توام به وسیله ریزوبیوم و سودموناس پوتیدا بیشترین شاخص های رشد و تیمارهای بدون تلقیح (شاهد) کمترین شاخص های رشد را به همراه داشته است.
    کلیدواژگان: باکتری های افزاینده رشد گیاه، علوفه، عملکرد علوفه، کود بیولوژیک
  • ماندانا محسنی، سیدمحمدمهدی مرتضویان، حسینعلی رامشینی، بهروز فوقی صفحات 524-542
    عملکرد دانه گندم در اکثر مناطق ایران به علت بروز تنش رطوبتی آخر فصل کاهش می یابد. به منظور بررسی اثر تنش رطوبتی بر عملکرد دانه 39 ژنوتیپ گندم بهاره، آزمایشی در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه پژوهشی پردیس ابوریحان- دانشگاه تهران در سال زراعی 90-1389 اجرا شد. اعمال تنش رطوبتی در مرحله ظهور سنبله به صورت کم آبیاری صورت گرفت. نتایج نشان داد در شرایط بدون تنش ژنوتیپ های پیشتاز و آزادی (8/27 و 7/72 تن در هکتار) و در شرایط تنش رطوبتی ژنوتیپ های مغان1 و سیستان (48/5 و 84/4 تن در هکتار) از بیشترین عملکرد دانه برخوردار بودند. براساس نتایج تجزیه رگرسیون در شرایط آبیاری معمولی و تنش رطوبتی سه متغیر وارد مدل شدند که در شرایط نرمال 70/8 و در شرایط تنش 64/03 درصد تغییرات عملکرد را توجیه نمودند. براساس میزان عملکرد ژنوتیپ ها در دو شرایط، 15 شاخص تحمل و حساسیت به تنش برآورد شد. نتایج تجزیه همبستگی، مولفه های اصلی و ترسیم بای پلات نشان داد که از بین شاخص های محاسبه شده MP، GMP، STI، HARM، YI، DI، MSTI و SNPI برای انتخاب ژنوتیپ های با پتانسیل و پایداری عملکرد بالا در شرایط تنش رطوبتی جزو مناسب ترین شاخص ها بودند. تجزیه خوشه ایبراساس شاخص های تحمل به خشکی، ژنوتیپ ها را در چهار گروه جداگانه قرار داد به طوری که ژنوتیپ های متحمل به خشکی در گروه مشترکی قرار گرفتند. توزیع ژنوتیپ ها در فضای بای پلات، وجود تنوع ژنتیکی بین ژنوتیپ ها را نسبت به تنش رطوبتی نشان داد. بر این اساس ژنوتیپ های مغان 1، سیستان، اکبری، بیات، دز، بک کراس روشن بهاره، مهدوی و طبسی جزو متحمل ترین و ژنوتیپ های تجن، نوید، شیرودی، زاگرس، کرخه و ویری ناک به عنوان حساس ترین ژنوتیپ ها به تنش رطوبتی آخر فصل شناسایی شدند.
    کلیدواژگان: تجزیه مولفه های اصلی، تحمل به خشکی، رگرسیون، شاخص های تحمل
  • حامد اکبری، ابوالفضل درخشان، بهنام کامکار، سیدعلی محمد مدرس ثانوی صفحات 543-552
    دما و پتانسیل آب دو عامل محیطی اولیه تنظیم کننده جوانه زنی بذر می باشند. جوانه زنی یک جمعیت بذری در پاسخ به دما و پتانسیل آب با استفاده از مدل هیدروترمال تایم توصیف می شود. هدف از این مطالعه، برازش و مقایسه دو مدل هیدروترمال تایم نرمال و ویبول به داده های جوانه زنی یک توده بذری کرچک (Ricinus communis L.) بود. جوانه زنی بذور کرچک در محدوده ای از پتانسیل های آب (صفر، 0/3-، 0/6- و 0/9- مگاپاسکال) در دامنه دمایی کمتر از مطلوب (از 10 تا 35 با فواصل 5 درجه سانتی گراد) مورد آزمون قرار گرفت. نتایج نشان داد که مدل هیدروترمال تایم ویبول، برازش (RMSE=8.07%) و دقت (AIC=-5801) بیشتری در مقایسه با مدل هیدروترمال تایم نرمال به داده های جوانه زنی بذرهای کرچک داشت. براساس مدل هیدروترمال تایم ویبول، دمای پایه برای جوانه زنی بذرهای کرچک معادل 86/8 درجه سانتی گراد و ثابت هیدروترمال تایم معادل 833/10 مگاپاسکال درجه سانتی گراد ساعت برآورد شد. همچنین، پتانسیل آب پایه برای شروع جوانه زنی معادل 1/71- مگاپاسکال به دست آمد. پارامتر شکل در مدل هیدروترمال تایم ویبول حاکی از نامتقارن بودن داده های پتانسیل آب پایه و چولگی توزیع به راست بود. این نتایج برخلاف فرض نرمال بودن توزیع پتانسیل آب پایه در یک جمعیت بذری است. بنابراین، پیش از استفاده از مدل هیدروترمال تایم، توزیع پتانسیل آب پایه در یک نمونه بذری باید مورد بررسی قرار گیرد و یک معادله مناسب انتخاب شود.
    کلیدواژگان: پتانسیل آب پایه، توزیع نرمال، مدل هیدروتایم
  • رضا نصری، علی کاشانی، فرزاد پاک نژاد، سعید وزان، مهرشاد براری صفحات 553-569
    به منظور تعیین مناسب ترین تناوب دوگانه و میزان نیتروژن از نظر کارآیی زراعی، فیزیولوژیک، بازیافت و شاخص برداشت نیتروژن آزمایشی در سال زراعی 92-1391 در ایلام به صورت کرت های خرد شده بر پایه بلوک های کامل تصادفی در چهار تکرار اجرا شد. فاکتور اصلی در شش سطح شامل (آیش، گیاهان پرکو، بوکو، شبدر برسیم، تربچه روغنی و ترکیب سه گیاه رامتیل، فاسیلیا، شبدر برسیم) و فاکتور فرعی کود نیتروژن در چهار سطح (صفر، توصیه کودی، 50% کمتر و 50% بیشتر از توصیه کودی) در نظر گرفته شد. میان سطوح فاکتور اصلی از نظر عملکرد دانه اختلاف معنی داری وجود داشت. تناوب بوکو: گندم با میانگین 8345 کیلوگرم بالاترین و تناوب آیش: گندم با 4491 کیلوگرم کمترین دانه را تولید نمود. بیشترین جذب نیتروژن در تناوب بوکو: گندم و کمترین در تناوب شبدر: گندم مشاهده شد. اختلاف میان تناوب های مختلف از نظر کارآیی زراعی نیتروژن معنی دار بود و در تناوب تربچه روغنی: گندم به ازای هر کیلوگرم نیتروژن مصرفی عملکرد اقتصادی 20/36 کیلوگرم در هکتار افزایش یافت. با افزایش مصرف نیتروژن به جز تناوب آیش: گندم کارآیی زراعی سایر تناوب ها کاهش یافت. کارآیی فیزیولوژیک نیتروژن در تناوب آیش: گندم بیش از سایر تناوب ها بود و به ازای هر کیلوگرم نیتروژن جذب شده حدود 39 کیلوگرم عملکرد تناوب افزایش یافت. بیشترین کارآیی بازیافت نیتروژن در تناوب تربچه روغنی: گندم حدود 45% و پرکو: گندم حدود 36% مشاهده شد. بیشترین شاخص برداشت نیتروژن در تناوب بوکو: گندم (86/5%)، و پرکو: گندم (85%) و کمترین شاخص در تناوب آیش: گندم (79/28%) مشاهده گردید. در نهایت تناوب پرکو: گندم و بوکو: گندم به دلیل بالا بودن عملکرد اقتصادی تناوب مناسب و قابل توصیه در منطقه می باشند.
    کلیدواژگان: تناوب، شاخص برداشت نیتروژن، کارآیی بازیافت نیتروژن، کارآیی مصرف نیتروژن
  • هادی خزاعی، احمد زارع فیض آبادی صفحات 570-582
    این پژوهش در اردیبهشت 1389به مدت دو سال در مزرعه نمونه آستان قدس رضوی و با استفاده از یک آزمایش فاکتوریل بر پایه طرح بلوک های کامل تصادفی با چهار تکرار انجام شد. عامل اول فاصله بوته ها در سه سطح 20، 30 و 40 سانتی متر روی ردیف و عامل دوم روش برداشت یک و چند مرحله ای گوجه فرنگی رقم های پیل 347 بود. صفات مورد بررسی تعداد میوه در گیاه، وزن میوه در بوته، عملکرد کل، مواد جامد محلول، pH و نیروی انسانی مورد نیاز به ازاء هر تن وزن میوه بودند. نتایج تجزیه واریانس نشان داد اثر فاصله کاشت بر صفات تعداد و وزن میوه در بوته، عملکرد و تعداد کارگر برداشت، دارای اختلاف معنی دار بود. فاصله کاشت 40 سانتی متری بیشترین و فاصله 20 سانتی متری کمترین تعداد و وزن میوه در بوته را دارا بودند و 51 و 102 درصد اختلاف بین این دو فاصله کاشت به ترتیب برای صفات تعداد و وزن میوه در بوته مشاهده شد. حداکثر عملکرد میوه در فاصله 30 سانتی متری با 16/2 درصد و حداکثر تعداد کارگر برداشت در فاصله 20 سانتی متری با 10/5 درصد اختلاف در مقایسه با فاصله کاشت 40 سانتی متری که کمترین عملکرد و نیاز کارگر برداشت را دارا بود، مشاهده شد. اثر روش برداشت بر صفات وزن میوه در بوته، عملکرد و تعداد کارگر برداشت، دارای اختلاف معنی دار بود. با وجود اینکه روش برداشت چند مرحله ای به ترتیب از 9/9 و 9/6 درصد وزن میوه در بوته و عملکرد بیشتر برخوردار بود، ولی نیازمند 127/1 درصد تعداد کارگر برداشت بیشتر در مقایسه با روش یک مرحله ای بود.
    کلیدواژگان: اجزاء عملکرد، تراکم، مواد جامد محلول
  • احد جمشیدی زیناب، طاهره حسنلو، امیر محمد ناجی صفحات 583-597
    به منظور بررسی اثر تنش خشکی در مرحله گل دهی بر عملکرد و صفات فیزیولوژیک، مورفولوژیک و بیوشیمیایی گیاه کلزا، آزمایشی، در مزرعه پژوهشی مرکز تحقیقات کشاورزی و منابع طبیعی یزد طی سال زراعی 91-1390 انجام شد. آزمایش به صورت کرت های خرد شده در قالب طرح پایه بلوک های کامل تصادفی با سه تکرار انجام شد. نمونه برداری از گیاهان 7، 12 و 26 روز پس از اعمال تنش انجام شد. آبیاری به عنوان عامل اصلی در دو سطح به صورت آبیاری معمولی یا شاهد (آبیاری پس از 80 میلی متر تبخیر از تشتک کلاس A) و تنش در مرحله گل دهی (آبیاری پس از 160 میلی متر تبخیر از تشتک کلاس A) و ارقام (Oise، Triangle، Karun و SLM046) در چهار سطح به عنوان عامل فرعی در نظر گرفته شدند. نتایج نشان داد که تنش خشکی موجب کاهش معنی دار محتوای نسبی آب برگ و هدایت روزنه ای در کلیه ارقام مورد مطالعه کلزا گردید، در حالی که محتوای قندهای محلول، پرولین و عدد کلروفیل در اثر تنش خشکی افزایش یافت. در بین ارقام مورد بررسی ژنوتیپ SLM046 از نظر صفات عملکرد، وزن هزار دانه، تعداد غلاف در بوته، محتوای نسبی آب برگ و هدایت روزنه ای به سایر ارقام برتری داشت و در مقایسه با سایر ارقام نسبت به تنش خشکی متحمل تر بود. رقم SLM046 بالاترین و رقم Karun کم ترین عملکرد (به ترتیب با 2553 و 2178 کیلوگرم در هکتار) را در شرایط تنش به خود اختصاص دادند.
    کلیدواژگان: پرولین، عملکرد، قندهای محلول، مالون دی آلدهید، محتوای نسبی آب برگ
  • داود امیدی نسب، محمدحسین قرینه، عبدالمهدی بخشنده، مهران شرفی زاده، علیرضا شافعی نیا، عزیزه سقلی صفحات 598-610
    به منظور بررسی کاشت گندم در بقایای گیاهی ذرت (بی خاک ورزی) و تاثیر آن بر میزان بذر و کود نیتروژن مصرفی در راستای کشاورزی پایدار، آزمایشی به صورت اسپلیت فاکتوریل در قالب طرح پایه بلوک های کامل تصادفی با چهار تکرار و با سه عامل رقم، در دو سطح (بهرنگ (V1) و چمران (V2)، تراکم بذر در پنج سطح (50 (D1)، 100 (D2)، 150 (D3)، 200 (D4) و 250 (D5) کیلوگرم در هکتار) و کود نیتروژن از منبع اوره در 6 سطح (0 (N1)، 50 (N2)، 100 (N3)، 150 (N4)، 200 (N5) و 250 (N6) کیلوگرم در هکتار) در پاییز سال 1391 – 1390 در مزرعه کشاورزی واقع در جنوب دزفول به اجرا در آمد. نتایج تجزیه واریانس صفات مورد مطالعه نشان داد که اثرات رقم، کود نیتروژن و بذر مصرفی بر روی عملکرد و اجزای عملکرد دانه در سطح احتمال یک درصد معنی دار بود. مصرف بذر بیش از 100 کیلوگرم در هکتار عملکرد دانه را کاهش و افزایش مصرف نیتروژن تا سطح 150 کیلوگرم در هکتار موجب افزایش معنی دار در عملکرد دانه گردید. رقم چمران با میانگین عملکرد دانه 413/70 کیلوگرم در هکتار نسبت به رقم بهرنگ برتری داشت و همچنین بهترین عملکرد دانه در تراکم 100 کیلوگرم بذر در هکتار با میانگین 5 تن در هکتار به دست آمد.
    کلیدواژگان: رقم بهرنگ، رقم چمران، عملکرد دانه
  • مرتضی گرزین، فرشید قادری فر، ابراهیم زینلی، سید اسماعیل رضوی صفحات 611-622
    به منظور ارزیابی جوانه زنی و قدرت بذر سویا حاصل از تاریخ کاشت های مختلف، آزمایش مزرعه ای به صورت کرت های خرد شده در قالب طرح بلوک های کامل تصادفی در سه تکرار در دانشگاه علوم کشاورزی و منابع طبیعی گرگان در سال زراعی 1390 انجام شد. عامل اصلی شامل پنج تاریخ کاشت 31 فروردین، 23 اردیبهشت، 13 خرداد، 8 تیر و 31 تیر و عامل فرعی شامل سه رقم سویا ویلیامز، سحر و دی پی ایکس بود. برای ارزیابی کیفیت بذر از آزمون های جوانه زنی و قدرت بذر شامل آزمون پیری تسریع شده، سرعت رشد گیاهچه و هدایت الکتریکی استفاده شد. تاریخ کاشت اثر معنی داری بر جوانه زنی و قدرت بذر داشت. درصد جوانه زنی دو رقم ویلیامز و سحر در چهار تاریخ کاشت ثابت و بیش از 90 درصد بود، اما در تاریخ های کاشت 31 فروردین در رقم ویلیامز و 31 تیر در رقم سحر کاهش یافت. تاریخ کاشت اثر معنی داری بر درصد جوانه زنی در رقم دی پی ایکس نداشت. کشت های زود هنگام در بهار باعث کاهش قدرت بذر در هر سه رقم به دلیل وقوع دماهای بالا طی دوره پر شدن بذر شد. با تاخیر در کاشت قدرت بذر در هر سه رقم افزایش یافت، اما در دو رقم سحر و دی پی ایکس وقوع دماهای بسیار پایین و بارندگی زیاد طی مراحل نمو بذر در تاریخ کاشت 31 تیر باعث کاهش مجدد قدرت بذر شد. بنابراین توصیه می شود که برای تولید بذرهایی با کیفیت بالا از کشت های زودهنگام و نیز دیرهنگام پرهیز شود.
    کلیدواژگان: آزمون پیری تسریع شده، آزمون هدایت الکتریکی، کیفیت بذر
  • فهیمه مردانی، حمیدرضا بلوچی، علیرضا یدوی، امین صالحی صفحات 623-636
    به منظور بررسی عملکرد، اجزای عملکرد و پتانسیل کنترل علف های هرز در الگوهای مختلف کشت مخلوط ردیفی شنبلیله (Trigonella foenum-greacum L.) با انیسون (Pimpinella anisum L.)، آزمایشی در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی کشاورزی دانشگاه یاسوج در سال زراعی 91-1390 اجرا شد. تیمارها شامل کشت خالص شنبلیله و انیسون، کشت مخلوط تک ردیفی، دو ردیفی و سه ردیفی شنبلیله و انیسون بدون کنترل علف هرز و همان تیمارها با کنترل علف هرز بود. صفات مورد بررسی شامل عملکرد، اجزای عملکرد، ارتفاع و شاخص برداشت هرکدام از گیاهان در کشت خالص و مخلوط، شاخص های سودمندی و وزن خشک علف های هرز بود. نتایج نشان داد که تیمارهای مختلف از نظر تعداد غلاف در بوته، وزن هزار دانه، عملکرد دانه و عملکرد زیستی شنبلیله با یکدیگر اختلاف معنی داری داشتند و ارتفاع بوته، تعداد شاخه در بوته، تعداد دانه در غلاف و شاخص برداشت تحت تاثیر تیمارها قرار نگرفتند. در گیاه انیسون نیز بین تیمارهای مختلف از نظر تعداد شاخه فرعی در بوته، تعداد چتر در بوته، تعداد دانه در بوته، عملکرد زیستی و عملکرد دانه اختلاف معنی دار وجود داشت. ولی اختلاف معنی دار در ارتفاع بوته، تعداد چترک در بوته، وزن هزار دانه و شاخص برداشت مشاهده نشد. پایین ترین وزن خشک علف های هرز با 35/10 گرم در مترمربع در کشت مخلوط دو ردیفی مشاهده شد و بیشترین وزن خشک علف های هرز با 72/43 گرم در مترمربع در کشت خالص شنبلیله به دست آمد. ارزیابی نسبت برابری زمین نشان داد که کشت مخلوط شنبلیله و انیسون بر کشت خالص آنها برتری دارد و کشت مخلوط تک ردیفی بیشترین نسبت برابری زمین (1/39) را به خود اختصاص داد. همچنین کلیه مقادیر شاخص کاهش عملکرد واقعی مثبت بودند که نشان دهنده سودمندی کشت مخلوط نسبت به تک کشتی هریک از گیاهان است. در کل پیشنهاد می گردد در مناطقی که مشکل رشد زیاد علف هرز را دارند کشت مخلوط تک ردیفی انیسون با شنبلیله مناسب تر است.
    کلیدواژگان: اسانس، چند کشتی، علف هرز، کاهش واقعی عملکرد، نسبت برابری زمین
  • خسرو پرویزی، علی قدمی فیروز آبادی صفحات 637-650
    به منظور بررسی تاثیر روش های کم آبیاری بر رقم جدید ساوالان آزمایشی در قالب طرح کرت های خرد شده با سه تکرار در مرکز تحقیقات کشاورزی و منابع طبیعی همدان از سال 1387 به مدت دو سال زراعی انجام شد. فاکتور اصلی شامل تیمارهای آبیاری در سطح50، 60، 70، 80، 90 و 100 درصد نیاز آبی گیاه و فاکتور فرعی کلون ها و ارقام مورد بررسی شامل سه کلون جدید سیب زمینی و رقم جدید ساوالان به همراه سانته به عنوان شاهد بود. سیستم آبیاری مورد استفاده روش آبیاری قطره ای بود. صفات مورد اندازه گیری شامل صفات مورفولوژیکی و فنولوژیکی رشد، میزان قند احیاء غده، غده ریز و بدشکل و عملکرد کل بود. نتایج تجزیه مرکب واریانس داده های حاصل از دو سال آزمایش نشان داد که تنش آبی و نوع کلون در صفات تعداد ساقه اصلی، زمان پوشش کامل، زمان گلدهی، طول مدت گلدهی، زمان رسیدن، وزن تر و خشک ریشه و عملکرد کل معنی دار شد. در میزان قند احیاء هرچند تیمار آبیاری تفاوت معنی دار در سطح 1% ایجاد کرد اما اثر رقم معنی دار نشد. اثر متقابل رقم و تیمار آبیاری در وزن تر و خشک ریشه، زمان رسیدن، وزن غده ریز و عملکرد کل معنی دار شد. درمجموع کاهش آب آبیاری تا حد 80 درصد نیاز آبی اثر منفی بر صفات رشد و عملکرد کل نداشت هرچند واکنش کلون ها و دو رقم ساوالان و سانته متفاوت بود. با تامین نیاز آبی 80 درصد، رقم ساوالان با متوسط تولید 4/5 کیلوگرم در متر مربع به همراه دو کلون 13-3970015 و 2-397008 بیشترین میزان غده را تولید کردند.
    کلیدواژگان: تنش آبی، تیمار آبیاری، عمکرد، واکنش رشد
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  • Kh. Parvizi*, A. Ghadami-Firooz Abadi Pages 435-447
    Introduction
    Water deficiency is the main factor that limits crop production in arid and semiarid regions. Due to limitation in water resources، low efficiency of water in surface irrigation method and irregular rainfall application of sprinkle and triple irrigation methods is inevitable in more regions of Iran. In this respect، it is crucial to employ methods that can improve water use efficiency and do not damage the sustainable production of potato in these regions. Introduction of some potato cultivars that have good capability of yield in deficit irrigation is anopportunity in this case. In previous study new released potato cultivar (Savalan) and three other promising clones had more yield and growing potential compared with Agriacultivar. Therefore، it was necessary to evaluate new cultivar (Savalan) and promising clones in water deficit irrigation. In this respect، as is expected، if cultivars or clones have more tolerance to water deficit they canbe suitable cultivar candidate and germplasms in water critical water conditions in many regions of Iran.
    Material And Methods
    This experiment has been conducted in Agricultural and Natural Resources Research Center of Hamedanin split plot design based on Randomized Complete Block in three replications with two factors، including: 1. Water deficit irrigation treatment، 50، 60، 70، 80، 90 and 100% of regular potato irrigation requirement. 2. Three clones accompanied with Savalan and Sante Cultivars. Irrigation system was tape method. Irrigation treatments were established immediately after cultivation of tubers. Water requirement was calculated through corrected vapotranspiration (ETo) determined by Penman-Monteith equation considering 90% water use efficiency. During the growing season، fewgrowing indices including، flowering longevity and harvesting time were recorded along with measurement of dry and fresh root weights. Total yield was measured by selecting randomly of 2 m2in every plot. Harvested tubers were separated as marketable and non marketable. Reducing sugars of tuber were calculated by titration and volume accuracy method. Tow-way analysis of variance (ANOVA) of the data was carried out using SAS software and the means were compared through the Duncan’s Multiple Range Test.
    Results And Discussion
    multiple analysis of variance of two years demonstrated that water treatment and clone effects were significant at 1% α level on number of stem، time and longevity of flowering، overlapping time، senescing time،fresh and dry root weight، unmarketable yield and total yield. Water regimes had significant effect on reducing sugars but cultivar had not the same effect. Means comparison of main stem showed that providing 80% water requirement had uppermost effect (No average of 6. 16 per plant)، since it didn’t significant difference with 90% and 100% of water requirement. Canopy overlapping time delayed as water supplement decreased. Three clones and Savalan showed similar reaction، but differences were significant as compared with other cultivar (Sante). It seems that supplementing of water requirement as 70% and upper than that have intensified the effect of cultivar on time of flowering and its longevity. Mean comparison of fresh and root dry weight showed significant effect of interaction between cultivar and irrigation levels. 397008-2 clone had more fresh and dry root weight in all irrigation levels as compared to other clones and cultivar. Mean comparison showed that 50 and 60 percent of water requirement increased in tuber. Three higher levels of irrigation regimes (80، 90 and 100 percentage of water requirement) showed the same effect on reducing sugar of tubers and didn’t show significant difference with each other. Supplying water requirement (100%) produced highest yield (6. 25 kg m-2) and didn’t show significant with 80 and 90 percent of water supplement. In this research، there were different reaction between clone/cultivar in main stem and overlapping time for different irrigation regimes. The differences of flowering dateand its longevity between clones in different water treatments demonstrated that although flower longevity of potato is a qualitative trait related to cultivar inherit but it can be affected by environment condition like temperature، light intensity and soil moisture. In this research there have been remarkable changes in reducing sugar of tubers under different irrigation levels. Therefore we can conclude that by determining good strategy for water use management in potato، both water stresses and higher reduction of sugar can be avoided. This result was consistent with previous studies (12، 14 and 18) that evaluated the effect of water stress and water deficiency on qualitative characters of potato. Decreasing 20 percent water requirement of potato، resulted only 0. 7 kg decrease of total yield per square meter. As a result، it can be save more than 40 million cubic meter of water only in Hamedan state every year. Moreover، if we apply some suitable cultivars same as Savalan and other promising clones that have more tolerance to water deficit، it can be more efficient.
    Conclusions
    Totally، the result of the this research showed that decreasing water requirement of potato until 20% not only did not impair the growth and performance of potato but also did not show adverse effects on qualify of harvested tuber. It is also found that Savalan and two clone had more advantage in comparison with others.
    Keywords: Water stress, Irrigation treatment, Potato, Yield, growth reaction
  • A. Koocheki, S. Bakhshaie, S. Khorramdel, V. Mokhtari, Sh Taherabadi Pages 448-460
    Introduction
    Plant association with mycorrhiza has been considered as one of the options to improve input efficiency particularly for water and nutrient - (Allen and Musik, 1993; Bolan, 1991). This has been due to kncreasing the absorbing area of the root and therefore better contact with water and nutrients. Inoculation with mycorrhiza enhances nutrient uptake with low immobility such as phosphorus and solphur-, improve association and could be an option to drought and other environmental abnormalities such as salinity (Rice et al., 2002). Moreover, higher water use efficiency (WUE) for crops -has been reported in the literatures (Sekhara and Reddy, 1993).The sustainable use of scarce water resources in Iran is a priority for agricultural development. The pressure of using water in agriculture sector is increasing, so creating ways to improve water-use efficiency and taking a full advantage of available water are crucial. Water stress reduce crop yield by impairing the growth of crop canopy and biomass. Scheduling water application is very crucial for efficient use of drip irrigation system, as excessive irrigation reduces yield, while inadequate irrigation causes water stress and reduces production. The aim of present study was to evaluate the symbiotic effect of mycorrhiza on yield, yield components and water use efficiency of sesame under different irrigation regimes in Mashhad.
    Material And Methods
    In order to investigate the impact of inoculation with two species of Arbuscular mycorrhiza fungi on yield, yield components and water use efficiency (WUE) of sesame (Sesamum indicum L.) under different irrigation regimes, an experiment was conducted as split plot based on a randomized complete block design with three replications during two growing seasons 2009-2010 and 2010-2011 at the Agricultural Research Station, College of Agriculture, Ferdowsi University of Mashhad.. The experimental factors were three irrigation regimes include 2000, 3000 and 4000 m3 ha-1, inoculation with two species of mycorrhiza fungi (Glomus mosseae and G. intraradices) and control allocated to the main and sub plots, respectively.
    Results And Discussion
    Results showed that the effect of irrigation regimes were significant (p≤0.05) on yield components except 1000-seed weight, biological yield, seed yield, harvest index (HI) and WUE based on biological yield and seed yield. By increasing the irrigation level from 2000 to 4000 m3 ha-1 biological and seed yield enhanced up to 52% and 118%, respectively. Increasing the irrigation level from 2000 to 4000 m3 ha-1 also improved WUE based on seed yield up to 22%. Inoculation with mycorrhiza species had significant effect on yield components, biological yield, seed yield, HI and WUE based on biological yield and seed yield P ≤ 0.05). Inoculation with G. mosseae improved seed yield compared to G. intraradices and control with 7 and 12%, respectively. These improvement of WUE based on seed yield were 7% and 24%, respectively. In general, mycorrhiza inoculation enhanced WUE through root system development and nutrient availability as this effect for G. mosseae was higher than G. intraradices.
    Conclusions
    Yield and yield components of sesame were generally more responsive to irrigation level under mycorhiza inoculation. Sesame yield and its components were significantly affected by irrigation treatments. Increase the irrigation level enhanced biological and seed yield- and also improved WUE. The water was used more efficiently in the deficit irrigation treatments where WUE increased with lower amounts of water. Inoculation with G. mosseae improved seed yield compared to G. intraradices and control. Mycorrhiza inoculation enhanced WUE due to root system development and nutrient availability. These results highlight the importance of determining the interaction effects between water level and mycorrhiza inoculation on yield of sesame to formulate proper management practices for sustainable production.
    Keywords: Mycorrhiza symbiosis, Oil crop, Root system development, Sustainable agriculture
  • H. Vahidi, Gh. R. Khajoeinejad, A. Rezaei Estakhroeih Pages 461-470
    Introduction
    Reduction of the forage and grain yield of sorghum genotypes under different levels of deficit irrigation has been reported. The plants that have higher water use efficiency (WUE), have a better chance of survival in arid regions. On average, WUE of sorghum in clay, loamy soil has been reported equal to 1.46 kg m-3. Effects of drought stress and different levels of nitrogen on yield of two cultivars of sorghum were investigated and results showed significant effects on plant height, leaf area index, fresh and dry weight of leaf, dry weight of stem and forage yield. The purpose of this research is to investigate the effect of deficit irrigation on grain yield and WUE of sorghum cultivars in Kerman.
    Materials And Methods
    This study has been conducted in the research station of Shahid Bahonar University of Kerman with 56o 58' E longitude, 30o 15' N latitude and 1753.8 altitudes. According to the regional information from 1952 to 2005, the average temperature is 17.1 oC, the average rainfall is 154.1 mm, the average annual relative humidity is 32%. The climate of Kerman according to De Martonne method can be classified as semiarid. The experimental design was split-plot based on RCBD with three replications. Three levels of irrigation (after 50, 80 and 110 mm evaporation from class A pan) were assigned to the main plots and the five sub-plots of sorghum cultivars (Speedfeed, Pegah, Payam, Sepideh and Kimia). On the 20th of May all sorghum cultivars were planted at the distance of 10 cm from each other on ridges. On the 7th of October, with considering margins, four square meters of the two middle lines were selected to determine the grain and biological yield. The samples were weighed with a digital scale and heated for 48 hours in the degree of 75 oC-and then the dry weight of each samples were measured again. Finally, the data were analyzed by SAS software (v. 9.1). Comparision of the averages attributes was performed using, Duncan’s test at five percent level of significant.
    Results And Discussion
    The result of the analysis of variance (Table 3) has shown a non-significant effect of different irrigation regimes on the study attributes. Grain yields of different cultivars were shown to have a significant effect (P < 0.01) (Table 3). Among the cultivars, Sepideh with the production of 7806.7 kg ha-1 of grain had the highest and Payam with the production of 4721.9 kg ha-1 had the lowest yield (Table 4). The results of the analysis of variance (Table 3) showed that the biological yield of the cultivars were significantly different (P < 0.01). Pegah showed the maximum dry matter production with 30365 kg ha-1 and Payam showed the minimum dry matter production with 12865 kg.ha-1 (Table 4). Harvest index of different cultivars was significantly (P < 0.01) different too (Table 3). The highest harvest index belonged to Sepideh with 43% and the lowest belonged to Pegah with 18% (Table 4). The highest WUE was 1.12 kg m-3 in Sepideh and the lowest of WUE were equal to 0.85 and 0.86 kg m-3 for Speedfeed and Payam, respectively (Table 4). The water use efficiency (WUE) based on the biological yield, between the cultivars was statistically significant different (P < 0.01) (Table 1). The highest WUE belonged to Pegah with 4.34 kg m-3 and the lowest belonged to Payam with 2.33 kg m-3 (Table 2). The lowest crop water requirement was 0.91 m3 kg-1 for Sepideh and the highest was equal to 1.32 m3 kg-1 for Pegah (Table 2). Overall, the results showed that Sepideh is the most appropriate cultivar for the grain yield in arid regions.
    Conclusions
    The cultivar Sepideh with producing grain yield of 7806.7 kg ha-1 and the water use efficiency (WUE) of 1.12 kg.m-3 is the best choice for the region of Kerman. On the other hand, with the purpose of cultivating sorghum, biological yield, and achieving the minimum water requirement for biological yield of sorghum in this region, Pegah cultivar is the best suggestion.
    Keywords: Crop water requirement, Deficit irrigation, Drought stress, Evapotranspiration, Harvest index
  • S. Habibi, M. Meskarbashee, M. Farzaneh Pages 471-484
    Introduction
    Decrease in water quality affected by salinization of the water resources due to the drought is one of the limiting factors of plant production. Using mycorrhizal fungi is an important approach to deal with damaging effects during stress conditions. The symbiosis of arbuscular mycorrhiza (AM) with the host plant and hence, the production of a very extensive network of hypha, enhances nutrient acquisition and improves water uptake in the host plant. The specialized network of hypha raises the uptake and translocation of nutrients to the plant, whereas it inhibits high uptake of Na and Cl and their transport to plant shoots compared with plant roots. Hence, AM can alleviate the stress of salinity on plant growth and increases their tolerance to the stresses.
    Materials And Methods
    In order to evaluate the influence of mycorrhizal fungi on yield and yield components of wheat, a greenhouse experiment was conducted in research farm of Shahid Chamran Ahvaz University. Experimental design was a randomized complete block design arranged in split factorial with three replications. The factors were water salinity (water quality) including filtered water (EC ≥ 1 dS m-1), tap water (EC = 1/7-3 ds m-1), tap water plus NaCl and filtered water plus NaCl (EC = 8 ds m-1). Soil sterilization included sterilized and non-sterilized soil and mycorrhizal inoculation were in five levels (non-inoculated, inoculated with ‌Glomusmosseae, G. intraradices, G. geosporum and mixture of them). Yield and yield components were measured at crop maturity and colonization percentage of root was determined at flowering stage. Root colonization by AM was determined through preparing root samples at 1 g in each experimental unit, and roots were stained using the Gridline- Intersect Method. The harvest index and mycorrhizal dependency were also measured. Salinity levels determined approximate the threshold of wheat –tolerate- salinity before the results would rather reflect saline stress on mycorrhizal symbiosis than on wheat plants.
    Results And Discussion
    The results showed that salinity decreased colonization percentage and grain number per spike but it did not affect yield and yield components significantly. In non- inoculated soil, the formed mycorrhizal symbiosis by indigenous fungi improved colonization percentage, while it did not result in significant differences of the yield and its components. The inoculation with mycorrhiza fungi was successful. Mycorrhizal colonization rates of 15-32% and mycorrhizal dependency rates of 7-13% were observed in the inoculated treatments, and this effect led to significantly higher grain yield, spike number and grain number per plant in compare with control. Furthermore, there was a significant interaction on colonization percentage and whole yield components between AMF inoculation and salinity except for spike number. Spike per plant, grain number per spike and colonization percentage affected by mycorrhizal inoculation in interaction with soil sterilization. Colonization percentage was positively correlated with spike number, grain number per plant and grain yield (significant at α=1%).
    Conclusions
    Enhanced yield under all mycorrhizal treatments related to higher grain number per plant, whereas there was no significant difference between these treatments for grain weight. Although the colonization levels of individual mycorrhizal treatments were generally lower, the fostering of grain yield was even strongly more pronounced than with mixed mycorrhizal treat (significant at α=1%). Effects of salinity and soil sterilization varied depending on the species of fungi and water quality. In comparison with other mycorrhizal treatment, G. geosporum showed higher salt tolerant relatively on display of superior colonization percentage and grain number per plant in salinity with tap water; and the colonization percentage by G. mosseae was not affected by soil indigenous fungi. The results showed that salinity decreased colonization percentage of inoculated mycorrhiza besides indigenous fungi, whereas mycorrhizal dependency was not influenced by salinity levels. Mycorrhizal dependency would probably provide a more consistent basis for the relative benefit provided by mycorrhiza at the saline condition than the colonization percentage. Reductions of the mycorrhizal dependency to wheat plants caused by increasing soil water or nutrient availability however enhancement of plant growth have been indicated especially when mycorrhizal wheat plants exposed to saline stress.
    Keywords: Indigenous Fungi, Mycorrhizal Dependency, Root Colonization Percentage, Salinity
  • A. Sepehri, M. Samadi Pages 485-495
    Introduction
    Isabgol (plantagoovata Forssk) is an important annual medicinal plant which is under cultivation in Iran. Isabgol has been used in medicine since ancient times, however, it has only been cultivated as a medicinal plant in recent decades. It is a diuretic, alleviates kidney and bladder complaints, gonorrhea, arthritis and hemorrhoids. In general, plants known as medicinal are rich in secondary metabolites and have potential as drugs. The biosynthesis of the secondary metabolites is controlled genetically and affected strongly by environmental factors especially chemical fertilizers. The environmental and economic impacts of chemical fertilizer application such as water pollution, low quality of agricultural production and decreasing soil productivity have encouraged farmers to use alternative nutrient sources. Sustainable farming on the basis of natural fertilizer application with the aim of omitting or decreasing chemical elements is a desirable approach to prevent these problems. Biofertilizers are some non-symbiotic and symbiotic microbes in the soil that stimulate plant growth and contribute the improvement of ecosystem. Many genera of plant growth promoting rhizobacteria such as Azospirillum, Azotobacter, Bacillus and Pseudomonas are used as biofertilizers for economically important crops. Several studies have shown that beneficial microbes, such as Azotobacter and Azospirillum, not only affect nitrogen fixation but also exhibit other favorable properties such as production of growth hormones. Nitrogen and phosphate chemical fertilizers could be replaced by biofertilizers containing Azotobacter, Azospirilium, Bacillus and Pseudomonas. In this study, we evaluated the effects of integrated application of chemical fertilizers and bio-fertilizers under different plant densities on growth indices, grain and mucilage yield of Isabgol.
    Materials And Methods
    A field experiment was conducted based on randomized complete block design with three replications at the Agricultural Research Station of Bu-Ali Sina University in2011. The mean annual precipitation was 330 mm. The Soil of experimental field was loamy clay with pH 7.7, containing 8.2 mg kg-1P, 0.1 mg kg-1N, 220 mg kg-1K, and EC 0.409 dS m-1. Three levels of plant densities (70, 100, and 130 plant per m2) and three combinations of fertilizers including 100% chemical fertilizer (control), 50% chemical fertilizer+Nitroxin (Azotobacter sp., Azospirilium sp.) and Biophosphorus (Bacillus sp., Pseudomonas sp.), 25% chemical fertilizer+Nitroxin and Biophosphorus were applied. Two biofertilizers including Nitroxin (2 liters per hectare) and Biophosphor (100 gram per hectare) were used. The population of bacteria in Nitroxin was 108 cell ml-1 and in Biophosphorus was 107 cell gr-1.The plant height, number of branches in plant, maximum leaf arearindex (LAImax), maximum crop growth rate (CGRmax), total dry matter (TDM), and grain and mucilage yield was measured. All variables were submitted to analysis of variance using the statistical analysis system (SAS, 9.1) and significant differences among means were identified by Duncan test at the 0.05 level of significance.
    Results And Discussion
    The interaction between density and fertilizer treatments was significant forplant height, number of branches in plant, LAImax, CGRmaxTDM, grain and mucilage yield, whereas it was not significant for length of spike. Acrossall fertilizer treatments, increasing plant density decreased the number of branches per plant. The grain yield obtained from 130 plants per m2 was on average 15.49% and 41.44% higher than 100 and 70 plants per m2, respectively. Grain yield was mostly affected by the application of 50 % of chemical fertilizer + biofertilizersfor allthree plant densities. The highest mucilage yield and TDM (314.69 unit and 497.65 gr m-2, respectively) were obtained from 130 plants per m2 by using 50% of chemical fertilizer + biofertilizers. In density of 130 plant per m2, there was no significant differencebetween using 100% chemical fertilizer and 50 % of chemical fertilizer + biofertilizers. The lowest mucilage yield was obtained from 70 plants per m2 by using 25 % of chemical fertilizer + biofertilizers.Conclutions: The integrated application of chemical fertilizer and biofertilizer showed maximum effect on growth indices and the quality and quantity characteristics of Isabgol, therefore application of 50% chemical fertilizers+biofertilizers and 130 plants per m2 is recommended in similar conditions.
    Keywords: Biophosphorus, CGR max, LAI max, Nitroxin
  • S. Y. Mousawi Toghani, P. Rezvani Moghaddam, M. Nasiri Mahalti, M. R. Damavandian Pages 496-512
    Introduction
    Diversity reflects the complexity of a system and can maintain its sustainability. Higherdiversity, results in higher inherent complexity of agro-ecosystems and strengthen their processes. It is necessary to realize the spatial distribution and temporal properties of the biodiversity components in agro-ecosystems, for the conservation and optimal utilization. Since weeds as a complementary component of agro-ecosystems and are inseparable, so the study of species, their functional and structural diversity of them can play an important role in weed management and balance in ecological systems.
    Materials And Methods
    This study was performed to determine the effects of different management systems on structural, and functional diversity of paddy weeds in Mazandaran province. Three rice fields, ranged from 0.3 to 0.5 ha, were chosen for each management system. Samples were collected from three fields running under each selected management system (organic and conventional). Data (number of weed species and their density) were randomly gathered from 9 quadrates (1m×1m) per each field in four stages (tillering, stem elongation, grain filling and after harvest). The diversity, evenness, frequency and similarity indices for weeds were determined at genera and species level. Data analysis carried out through T-test and grouping performed via cluster analysis as hierarchy.
    Results And Discussion
    All monitored weeds can be classified into four plant family including cereals (Poaceae), sedges (Cyperaceae), plantain (Plantaginaceae) and chicory (Asteraceae).Under conventional systems the values of weed diversity indices were higher during tillering and stem elongation compared with organic ones, and were lower during grain filling and after harvest stages. However indices of weed evenness showed contrary tendency. Both Sympson and Shanon-Wiener diversity indices, consist of two clusters in 76% similarity. Evenness indices of Kamargo and Smith-Wilson included two clusters in 83% and 82%, respectively. Range of similarity index was between 1.89% and 83.96%. Weed grouping based on relative frequency during the sampling stages showed two clusters in 78% and four clusters in 85% similarity. Clustering weeds centered on relative frequency during sampling stages, according to the family, showed different results. It might be the reason that the relative abundance of weeds, sedge family (79%) were in two clusters. However, sampling stages grouping based on weed density, induced two clusters in 39% similarity. Both conventional and organic systems, are included 10 species of 8 genera of four families. The 75 percent of families based on the vegetative form were monocots and 25% of them were dicots, so monocots had more diversity. Perhaps the presence of Alismaplantagoin the conventional system could be as a unique species and its absence in the organic system, attributable to duck existence in it. Based on life-cycle, 6 species were annual and 4 were perennial. While, according to the photosynthetic pathway, 50 percent species were C3 and others had C4 pathway. Based on the characteristics of the interference, 4 species were noxious and 6 species were non-noxious. Poaceae were the most diversity of weeds in monocotyledon and C4 pathway (three species). Two species of noxious weeds and herbicide resistant belong to Poaceae too. The Cyperaceae consist of two species from four perennial ones. The weeds of Poaceae and Cyperaceae families include 70% of total weed. Generally, weeds in ecosystems usually change thehabitat conditions or impact on the resources availability for other species.
    Conclusions
    Due to repeated or severe disturbances, agro-ecosystems are limited to the early stages of succession. Thus, the widespread destruction of agro-ecosystems during consecutive years, by changing the succession, weed population dynamics was affected as well. It should be noted that the differences of weed distribution in the various stages of the sampling in both conventional and organic systems, can be related to dissimilarities in management practices. The presence of various species of grass and sedge family in paddies, could be related to the ecological niche differentiation, because of ecological divergence amongst the different photosynthetic pathways (such as C. rotundus, C4 and C. difformis, C3) or the variance between water requirements (such as Echinochloa crus-galli in wet conditions and flooding and Digittaria spp. in dry conditions). Sound management in these conditions can the switch a threat into an opportunity, so that with regard to interaction among weeds and other communities such as insects, in rice agro-ecosystems, the emerging phenomena at this level would be beneficial. It seems, realizing species, structural and functional diversity of weeds in rice agro-ecosystems, can be result in better management of farm production with the aim of provide ideal use of resources.
    Keywords: Clustering, Density, Frequency, Kamargo index, Sympson index
  • R. Azamei, M. R. Ardakani, M. Gomarian Pages 513-523
    Introduction
    Over the past decades, world attitude has changed towards the reduction of environmental pollutants. Harmful effects of synthetic fertilizers on environment have been identified. Bio-fertilizers are not harmful to the environment, but also they have favorable effects on plant growth processes. Soil biotechnology can be defined as the study of soil organisms and their metabolic processes which may have positive effects on plant yields. The main goal of this study is to asess the biotechnology fertilizers beneficial effects on soil organisms and their subsequently to maximize the yield. It is also our desire conside the soil quality, hygiene and environmental protection along this process. Among the strain of nitrogen-fixing bacteria, symbiotic bacteria such as rhizobium bacteria are important and essential in planning the sustainable farming systems. Several studies have shown that crop varieties which inoculated with rhizobium and pseudomonas were superior in yield production and performance.
    Material And Methods
    An experiment was designed as factorial performed in randomized complete block design (RCBD) with three replications in Agricultural Research Center of Golpayegan (Isfahan) during 2010 – 2011. the purpose of this study was to evaluate the effects of inoculation of two ecotypes of Persian clover by various strains of Rhizobium leguminosarum. Biovar trifoli bacteria accompanied with plant growth promoting rhizobacteria (PGPR) Pseudomonas putida was employed to find certain qualitative and quantitative characteristics of clover yield, The main plots included two local ecotypes of Persian clover; Arak Haft Chin (V1) and Isfahan Haft Chin (V2)), the subplots included inoculation by two strain of Rhizobium; Rb-3, Rb-13 and one strain of Pseudomonas; PS -168.4 cuts were performed during the experiment and 60 kg/ha seed was used for cultivation based on local knowledge. According to recommendations of the Institute of Soil and Water the powder used for inoculum was 5 gram from every bacterium seed (Containing 108 × 5 bacteria per gram) for 100 kg seed. For better adhesion of the bacteria on the surface of seed, water with 20% sugar solution was used. (2) Sampling performed by harvesting 2 meter of every plot and 2 kg of fresh yield was transferred to oven (48 hours) with (72 °C) to determine dry matter. The crude protein content was determined by multiplying nitrogen content by the correction factor (6.25). At the end of the season a few plants from each plot were selected, and the number of nodules formed on the roots were counted and secondary roots with the highest penetration depth were measured by ruler. Analysis of variance and the means of treatments were performed using SAS software. Average interaction MSTAT- C treatments were performed using the software and the treatments were compared based on Duncan method.
    Results And Discussion
    The results showed that the qualitative factors have not been affected by Rhizobium and Pseudomonas bacteria so that the differences between treated plots with control were not significant. The quantitative factors except for depth of root penetration were affected by inoculation with Rhizobium and Pseudomonas bacteria and a significant difference between treated plots and control was obtained. Roberts et al. (3) reported that delay in planting caused plant growth exposure to high temperatures and long days, thus cell walls were stimulated to increase fiber and protein content and consequently digestibility was extremely reduced. The results indicated that inoculation by both bacteria (Rhizobium and Pseudomonas) has affected quantitative indicators of growth significantly and increased fresh and dry yield, plant height, leaf/stem ratio and the number of nodes on roots. However the results showed that the qualitative characteristics and root infiltration did not change significantly by inoculation of both bacteria. Plant growth promoting rhizobacteria (PGPR) leaded to an increase in the growth of quantitative traits. Inoculation with Rhizobium and Pseudomonas putida in most of the cases combined with the highest growth and treatments without inoculation (control) had the lowest growth as well. Dilip Kumar et al. (1) demonstrated that the combined inoculation of pea seeds with Rhizobium and Pseudomonas leads to an increase in plant height, root length and dry weight compared to control treatments. However the present study has shown the positive impacts of biological fertilizers on some of the growth parameters, but the important thing is the proper use of biological fertilizers. It was also concluded that the date of planting in spring is very important and delayed planting can affect forage quality.
    Conclusions
    This study showed that biofertilizers can have positive effects on growth characters of clover, and requires more research.
    Keywords: Biological fertilizer, Forage yield, Plant growth promoting rhizobacteria
  • M. Mohseni, S. M. M. Mortazavian, H. A. Ramshini, B. Foghi Pages 524-542
    Introduction
    Wheat is a major crop among cereals and plays a vital role in the national economy of developing countries. Wheat (Triticum aestivum L.) is one of the most important crops in terms of acreage and production rates in the world. This crop has an important role in the food supply. According to the FAO (2010) statistics report, the average wheat yield in Iran was 2136 kg ha-1, while the worldwide average yield was 3009 kg ha-1. Iran, with an average annual rainfall of 250 mm, is located in the world desert belt. Yield loss due to drought stress is likely higher than other stresses. Therefore, introducing plants with high production under both drought stress and non-stress conditions is highly regarded. Stress tolerance indices are used for screening drought tolerant varieties. Tolerance (TOL), mean productivity (MP), stress susceptibility index (SSI), geometric mean productivity (GMP), stress tolerance index (STI) and modified STI (MSTI) have been employed under various conditions. Fischer and Maurer (1978) explained that cultivars with an SSI less than a unit are stress tolerant, since their yield reduction under stress conditions is smaller than the mean yield reduction of all cultivars (Bruckner and Frohberg, 1987). Mean productivity, GMP, harmonic mean (HM) and STI were reported as preferred criteria in selection of drought-tolerant barley genotypes by Baheri et al. (2003). Yield Index (YI) proposed by Gavuzzi et al. (1997), was significantly correlated with stress yield which ranks cultivars on the basis of their yield under stress. The genotypes with a high Yield Stability Index (YSI) are expected to have higher yield under both stress and non-stress conditions (Bouslama and Schapaugh, 1984). Mousavi et al (2008) introduced Stress Susceptibility Percentage Index (SSPI) as a powerful index to select extreme tolerant genotypes with yield stability. Fischer and Wood (1979) suggested that relative drought index (RDI) is a positive index for indicating stress tolerance. Lan (1998) defined a new drought resistance index (DI), which was commonly used to identify genotypes producing higher yield under both stress and non-stress conditions The objectives of this study were to evaluate the performance of different wheat cultivars under normal irrigation and drought stress conditions and to identify the most promising wheat genotypes for drought prone areas.
    Materials And Methods
    Thirty-nine spring bread wheat genotypes were evaluated under two irrigation regimes, normal and moisture stress at grain filling period for a year. Under normal conditions soil was irrigated up to field capacity, while under stress conditions after the onset of flowering, irrigation was delayed until wilting point took place. The study was conducted at College of Aburaihan, University of Tehran, Iran, in Pakdasht. The experimental design was a randomized complete block design with three replications. Standard cultural practices were applied for all experiments. At harvest, grain yield (t ha-1) was calculated on the basis of plot area.
    Results And Discussion
    Under normal irrigation, Pishtaz and Azadi (with 8.27 and 7.72 ton ha-1, respectively) and under stress conditions Moghan1 and Sistan (with 5.48 and 4.84 ton ha-1, respectively) had the highest grain yield. Based on regression analysis under normal and stress conditions, three variables entered the model and in normal conditions 70.8 percent and in stress conditions 64 percent of yield changes were explained. Based on grain yield, 15 susceptibility and stress tolerance indices were calculated. Results of correlation, principal component analysis and biplot display showed that GMP, STI, HARM, MP, YI, DI, MSTI and SNPI indices were the best criteria for genotype selection with high yield and stability in stress conditions. Cluster analysis (Ward method) was also used based on indices and grain yield in both normal and stress conditions to classify genotypes in similar classes. Dispersion of genotypes in the biplot, revealed genetic diversity among the genotypes under drought stress.
    Conclusions
    Results showed that Moghan1, Sistan, Akbari, Bayat, Dez, Spring Roshan-BC, Mahdavi and Tabasi genotypes were identified as tolerant and Tajan, Navid, Shirodi, Zagros, Vee/Nak and Kohdasht genotypes as susceptible genotypes to terminal drought stress. These genotypes can be used for further cross and genetic analysis for drought tolerance through diallel or generation mean analysis designs.
    Keywords: Drought tolerance, Principal component analysis, Regression, Tolerance indices
  • H. Akbari, A. Derakhshan, B. Kamkar, S. A. M. Modares Sanavi Pages 543-552
    Introduction
    Temperature and water potential are two of the most important environmental factors regulating the seed germination. The germination response of a population of seeds to temperature and water potential can be described on the basis of hydrothermal time (HTT) model. Regardless of the wide use of HTT models to simulate germination, little research has critically examined the assumption that the base water potential within these models is normally distributed. An alternative to the normal distribution that can fit a range of distribution types is the Weibull distribution. Using germination data of Castor bean (Ricinus communis L.) over a range of water potential and sub-optimal temperature, we compared the utility of the normal and Weibull distribution in estimating base water potential (b). The accuracy of their respective HTT models in predicting germination percentage across the sub-optimal temperature range was also examined.
    Materials And Methods
    Castor bean seed germination was tested across a range of water potential (0, -0.3, -0.6 and -0.9 MPa) at the sub-optimal range of temperature (ranging from 10 to 35 ˚C, with 5 ˚C intervals). Osmotic solutions were prepared by dissolving polyethylene glycol 8000 in distilled water according to the Michel (1983) equation for a given temperature. Seed germination was tested on 4 replicates of 50 seeds in moist paper towels in the incubator. The HTT models, based on the normal and Weibull distributions were fitted to data from all combinations of temperatures and water potentials using the PROC NLMIXED procedure in SAS.
    Results And Discussion
    Based on both normal and Weibull distribution functions, hydrotime constant and base water potential for castor bean seed germination were declined by increasing the temperature. Reducing the values of base water potential showed the greater need to water uptake for germination at lower temperatures and reducing hydrotime constant indicated an increase in germination rate by increasing the temperature. Compared with hydrothermal time model based on the normal distribution, Weibull hydrothermal time model gave a better fit (RMSE=8.07%) and more accurate (AIC=-5801) to seed germination data of castor bean. Based on Weibull hydrothermal time model, base temperature and hydrothermal time constant were estimated to be 8.86 ˚C and 833/10 MPa h, respectively. The osmotic potential from which the germination begins was (μ) -1.71 MPa. The shape parameter (λ) of the Weibull hydrothermal time model implied asymmetry of base water potential data and skewness of distribution to the right. A right-skewed distribution of b(g) has important ecological implications, as it means that the seed population have a greater reserve of seeds with very high values of b(g) and are therefore slow in germination, even under optimal conditions. The HTT model assumes that the timing, rate and percentage of seed germination for a constant temperature to be controlled by the difference between water potential of the seedbed and the b for a given percentile (b(g)). Most previous studies have assumed that b(g) is normally distributed. Our results suggested that the Weibull distribution may be more suitable than the normal distribution for seed germination modeling of castor bean. Similar to the normal distribution model the parameters of the Weibull HTT model can be readily interpreted to yield information about the frequency distribution of population for b(g), enabling comparison of the germination behaviors in different seed populations. The location parameter of Weibull HTT model (μ) specifies the lowest b(g) possible value in the population ((b(0)) that cannot be derived from normal HTT model. The median (M) and mode (Mo) can be readily determined by equations of and, respectively, from the μ, scale (σ) and λ parameters. The median specifies the value of b(50) for the population and the mode will specify the location of the peak of the probability distribution function for b(g). Another advantage of the Weibull distribution in this application is that it can approximate a range of b(g) distributions through changing the shape parameter.
    Conclusions
    Results of this research were in contrast with the assumption of a normal distribution of base water potential of a seed population. Hence, before using a hydrothermal time model for predictions the distribution of base water potential within a seed sample should be examined and an appropriate equation be selected.. Due to the flexibility of the Weibull distribution, this model provides a useful method for predicting germination and determining the distribution of base water potential.
    Keywords: Base water potential, Hydrotime model, Normal distribution
  • R. Nasri, A. Kashani, F. Paknejad, S. Vazan, M. Barary Pages 553-569
    Introduction
    There are about 160 species in Brassica genus, which are mostly annuals and biennials. The plants in this genus have potential for fodder uses. The progress in plant breeding science has produced new crop varieties for oil and forage usages. Perko varieties are derived from crosses between tetraploid plants of winter rapeseed (Brassica napus L.Var. napus) and Chinese cabbage (Brassica campestris L. var. sensulato). The new plants are superior to their parents from various aspects. Buko varieties are new amphiploid plants obtained by crossing between tetraploid winter rapeseed, Chinese cabbage and turnips (Brassica campestris L. var. Rapa). Oilseed radish with scientific name (Raphanus sativus L.) is a genus of the Brassica and consumption, oil, green manure, feed and fodder (24). This plant in many countries, including Canada, is cultivated in gardens as cover crop. Oilseed radish grows fast in the cool seasons. Ramtil (Guizotia abyssinica) belongs to the Compositae family, Phasilia (Phaceli atanacetifolia L.) belongs to Boraginaceae family and clover is from Fabaceae family that is grown for feeding purposes.
    Materials And Methods
    A field experiment was conducted from 2011 to 2012 in the Karezan region of Ilam, Iran (42º33′N, 33º46′E) on a silty-clay with low organic carbon (1.26%) and slightly alkaline soil (pH=7.9). This site is characterized as temperate climate with 370 mm annual precipitation. The experiment was arranged in a split plot based on randomized complete block design with four replications. The main plots consisted of 6 pre-sowing plant treatments (control, Perko PVH, Buko, Clover and Oilseed radish and combination of three plants Ramtil, Phaselia andclover), and sub plots covered four N fertilizer rates including no fertilizer N (Control), 50% lower than recommended N rate, recommended N rate and 50% more than recommended N rate. Winter wheat (cv. Pishtaz) was sown on mid-November with the row spacing of 15 cm and a seeding rate of 200 kg ha-1. Soil samples were collected after harvest of each crop from 0 to 30 cm and 31 to 60 cm soil depths using a soil auger. Wheat grain yield (according to 14% moisture) obtained by harvesting the central area of 3 in 10 m in each plot. Yield components were determined from two randomly selected areas (2m2) within each plot. Plant samples collected at harvest were separated into grain and straw and oven-dried at 60˚C for 72hr. Biomass and grain sub samples analyzed for total N content using a micro-Kjeldahl digestion with sulfuric acid. The terminology of N efficiency parameters was considered according to Delogu et al, (11) and Lopez-Bellido & Lopez-Bellido, (22), Rahimizadeh et al. (30), Limon-Ortega et al. (20) methods.
    Results And Discussion
    The results showed that there were highly significant differences (P ≤ 0.01) in forage yield. There were also significant differences (P ≤ 0.05) in total dry weight, protein content and protein yield between treatments. Perko varieties produced higher fresh and dry matter yield with 69,586 (kg ha-1) and 7147 (kg ha-1), respectively compared to other varieties. Buko varieties showed greater protein percentage with 23.36 compared to the rest of the varieties. The highest and lowest grain yield, with 8345, and 4491 (kg ha-1) were obtained for Buko; wheat rotation and fallow, wheat rotation, respectively. The highest and lowest nitrogen uptake was obtained for Buko; wheat and clover, wheat rotation, respectively. The differences between the rotations were significant for various agronomic nitrogen efficiency. The rotation of oilseed radish and wheat showed greater nitrogen economic performance with 36.20 kg ha-1. By increasing nitrogen rate agronomic performance decreased with the exception in fallow- wheat. Physiological efficiency of nitrogen in fallow-wheat rotation was more than 39 (kg kg-1) of nitrogen. The maximum efficiency of nitrogen recovery was obtained for oilseed radish: wheat and Perko PVH; wheat rotations with 45% and 36%, respectively. The highest nitrogen harvest index was observed in Buko; wheat rotation: (86.5%), and Perko: wheat (85%) and the lowest nitrogen harvest index was in fallow; wheat (79.28%).
    Conclusions
    The results showed that Perko; wheat and Buko; wheat rotations due to the higher economic performance in the region were appropriate rotations and were recommended for the study area.
    Keywords: Harvest index nitrogen, Nitrogen recovery efficiency, Nitrogen uptake efficiency, Pre, sowing
  • H. Khazaei, A. Zarea Feizabadi Pages 570-582
    Introduction
    One time tomato harvesting, in addition to labor saving, provides a possibility of increasing the cultivated area which lead to increase the total output (1). Varieties of tomato that has multiple harvest usually have a lower density in farm compared to one time harvest (2). In the late 1940s, the processing tomato industry in California was concerned that expected shortage of labor would prevent harvest of its increasing tomato production. Commercial use of the new variety and the new harvesting method, began in early 1960s. New harvesting method had a labor requirement of 2.9 hours per ton, compared with 5.3 hours per ton for hand-harvest in several times. Total labor use for the crop dropped from 13.5 million hours in the hand-harvest years to about 3.8 million hours per year in 1997, while fruit yield increased 4-fold (3).
    Materials And Methods
    This study was carried out in two years (2010-2011) at Mazrae Nemone Astan Ghods Razavi using a factorial experiment based on randomized complete block design with 4 replications. The first factor was planting space within row at three levels including 20, 30 and 40 cm and the second factor was harvesting method at two levels including multiple and one time on tomato variety hypeel 347. Measured traits included fruit number per plant, fruit weight per plant, yield, as quantitative also pH, brix as qualitative and labor consumption per each ton of harvested fruit were investigated. Each plot consisted of 5 rows with a length of 6 meters, the plant in the row bilaterally (a total of 10 lines per plot) were planted. Drip irrigation method was performed using the T-tape with 1.6 liters per hour. Harvesting started in mid-September and ended in late October. Fully ripe and healthy fruits were harvested and rotten fruits were not collected.
    Results And Discussion
    Quantitative traits Analysis of variance showed that the effect of year and planting space on all quantitative traits was significant while harvesting method significantly affected fruit weight per plant and fruit yield. Interaction between year and planting space had significant effect on the fruit number and weight per plant. Moreover, interaction of year and harvesting method had a significant effect only on fruit number per plant. Means comparison indicated that fruit number, fruit weight per plant and fruit yield in first year were 31.1, 21.3 and 20.1 percent higher than second year, respectively. The highest and the lowest fruit number and fruit weight per plant obtained on 40 cm and 20 cm, respectively. The maximum yield with 16.2 percent was observed in 30 cm space treatment compared to 40 cm which had the lowest rate on those traits. The maximum fruit number and fruit weight per plant obtained in the first year and 40 cm planting space while the minimum number obtained in the second year and 20 cm planting space,. The fruit harvested at several times had 9.9 and 9.6 percent higher than fruit weight per plant and yield respectively, compared to harvested method at once. The maximum and minimum of fruit number per plant achieved in the first year and several time harvesting also in the second year and harvested method at once, respectively with 45.5 percent difference. Qualitative traits Analysis of variance revealed that only year had significant effect on brix and pH. Means comparison showed that pH had 9.3 percent superiority in the first year compared to the second year while brix was 25.2 percent lower in the first year compare to the second year. Labor working time Analysis of variance showed that planting space, harvesting method and their interaction had significant effect on this labor time. Means comparison illustrated that the maximum labor time with 10.5 percent difference were observed in 20 cm planting space treatment compared to 40 cm which had the lowest rate on this trait. The fruit harvested multiple times method needed 127.1 percent more labor compared to harvested method at once. The highest and the lowest labor consumption with 151.6 percent difference, were observed in 30 cm and 20 cm respectively.
    Conclusions
    In tomato production increasing and decreasing of harvest’s expenses, increasing within row space from 20 to 30 cm and one-time harvesting method, had a very important role.
    Keywords: Brix, Density, Yield component
  • A. Jamshidi Zinab, T. Hasanloo, A. M. Naji Pages 583-597
    Introduction
    Rapeseed (Brassica napus L.) is one of the major crops cultivated mainly for oil, human consumption and renewable fuel all over the world. Drought stress is one of the most important abiotic factors which adversely affect growth, metabolism and yield of crops in semiarid and arid area. Drought stress during any particular growth stage of crops causes yield reduction. In order to evaluate the effect of drought stress on yield, physiological, morphological and biochemical characteristics of rapeseed in flowering stage, this field experiment was carried out in Yazd agricultural research institute during 2011-2012.
    Materials And Methods
    The experiment was conducted in split-plot design based on randomized complete blocks with three replications imposed. Irrigation was considered as the main plot at two levels including control (irrigation after 80 mm evaporation from class A pan) and stress in the anthesis stage (irrigation after 160 mm evaporation from class A pan) and cultivars (Oise, Triangle, Karun and SLM046) were considered as sub plots. Sampling was carried out 7, 12 and 26 days after drought stress imposed. In each plot, 7, 12 and 26 days after stop irrigation from flowering stage (drought stress treatment), 4-5 expanded leaves from above of canopy were harvested. Relative water content of leaves and stomatal conductance were recorded. Soluble carbohydrate and proline content were measured. The lipid peroxidation level of the leaves was determined by measuring the content of malondealdehyde. Yield and yield components (number of grains per pod, number of pod per plant and weight of 1000 grains) were recorded at maturity.
    Results And Discussion
    The results showed that drought and cultivar interaction on SPAD value was not significant after stress. The interaction of the drought on leaf relative water content was significant at 26 days after the stress. The results revealed that, drought stress led to a significant decrease in relative water content of leaves and stomata conductance in all cultivars. However, soluble carbohydrates and proline were increased after stress application. The interaction of drought on soluble carbohydrate was significant at 26 days after the stress. Interaction of treatments on leaf proline content in each sampling period was significant. The highest content of proline was observed in SLM046 (11.76 mM g-1 fresh weight) and the lowest proline content was observed in Oise cultivar (6.01 mM g-1 fresh weight). MDA content was increased in stress conditions. The highest MDA content was observed in Oise cultivar (1.15 µM g-1 fresh weight) 26 days after the stress and the lowest MDA observed in SLM046 cultivar (0.695 µM g-1 fresh weight) 7days after the stress. Analysis of variance for yield and yield components under irrigation regimes showed that, interaction of treatments on grain yield and weight of 1000 grains was significant. Triangle and SLM046 cultivars had higher grain yield in compare to the other cultivars. SLM046 exhibited the highest stress tolerance and also contained the highest yield, grain weight, number of pod per plant, relative water content and stomata conductance among all the cultivars. In addition, the highest and the lowest yield were observed in cultivars SLM046 and Karun (2553and 2178 kg ha-1, respectively), following stress application. Water deficit stress on canola decreased the number of pods per plant and the number of grains per pod.
    Conclusions
    Occurrence of drought stress during flowering reduced the number of grains per pod and canola yield. The results showed that, there was significant difference between cultivars for crop yield, weight of thousands grains, relative water content, stomata conductance, proline and carbohydrate content. Increased carbohydrate and proline content as osmolites caused lower cell water potential. The cultivars had different response to drought stress and the the highest yield and RWC were observed in SLM046 cultivar. Sugar and proline in the cell, the cell water potential decreased. The drought tolerance of SLM046 was better than other cultivars and had the highest yield and Relative water content.
    Keywords: MDA, Proline, RWC, Soluble carbohydrate, Yield
  • D. Omidi Nasab, M. H. Gharineh, A. Bakhshande, M. Sharafizade, A. Shafeinia, A. Saghali Pages 598-610
    Introduction
    Lots of studies have been conducted for increasing the wheat yield per unit area through sustainable agriculture, which is included low tillage and no tillage farming systems. Furthermore, nitrogen is the important element which is used to increase crop yield. On the other hand, if all the required conditions especially cultivar and fertilizer are at optimum level, but density is not appropriate, the maximum yield per unit area will not be achieved. Therefore, this study was conducted to evaluate the effect of seeding rates and nitrogen fertilizer on yield and yield components of wheat cultivars in corn residue.
    Materials And Methods
    An split factorial experiment in a randomized complete block design with four replications and three factors including cultivar at 2 levels, (Chamran (V1) and Behrang (V2)), seed density at 5 levels (50 (D1), 100 (D2), 150 (D3), 200 (D4), 250 (D5) kg ha-1) and nitrogen fertilizers from urea source at 6 levels (0 (N1), 50 (N2), 100 (N3), 150 (N4), 200 (N5), 250 (N6)) carried out in fall of 2011 – 2012 at Agricultural Farm located south of Dezful.
    Results And Discussion
    The results indicated that with increasing plant density, the number of spike and biological yield increased, however the number of grain in each spike and thousand seed weight decreased. Moreover, increasing nitrogen application resulted in increasing the number of spike, the number of grain in each cluster, thousand seed weight, biological yield and grain yield. seed consumption over than 100 (kg ha-1) decreased grain yield. In addition, applied nitrogen to 150 (kg ha-1) significantly increased grain yield. The effects of plant density on grain yield illustrated that the highest grain yield was obtained using 100 kg seeds per hectare. Furthermore, there were not any significant differences among 150, 200 and 250 kg seeds per hectare and they were at a lower level of grain yield. In addition, Chamran cultivar, with 413.70 (kg ha-1) average grain yield, was higher in comparison to Behrang cultivar and also the best grain yield was obtained in 100 kg ha-1 of seed density with the average of 5 ton ha-1. In the present experiment, increasing seed rate to 100 kg per hectare, increased grain yield. Grain yield had decreasing trend in higher plant density, probably due to high competition, adverse growing conditions and leaf area index reduction. According to the results of this study, increasing nitrogen to optimal values, which is depending on the climatic conditions in each region, increases grain yield. However higher application of nitrogen fertilizer, will not increase the yield proportionally. Nitrogen application with increasing the number of mature leaves causes increasing the ratio of photosynthesis to respiration, and finally it increases assimilate materials and yield. When nitrogen is higher than optimum level, shoots will over grow, the number of leaves which are in shade will be increased. Furthermore, photosynthesis to respiration ratio will decrease and most of the assimilates will be used by leaves in shadow, thus, the lower assimilates transferred to grain.
    Conclusions
    In general, plant density and nitrogen fertilizer can be used as important factors to increase wheat yield. According to the results of this study, Chamran cultivar had higher grain yield compared with Behrang cultivar. The highest grain yield was obtained in 100 kg per hectare seed density with 250 kg of nitrogen fertilizer per hectare. Since there were no significant differences between 150 and 250 kg of nitrogen fertilizer per hectare, 100 kg seed per hectare and 150 kg nitrogen per hectare can be introduced as the most appropriate treatment to increase the grain yield in this experiment. In this study it was observed that by reducing application of seeds and fertilizer, the grain yield per hectare was not reduced. Therefore, it seems that to produce enough grain yield of wheat, as the main crop in Iran, increasing the consumption of seed and fertilizer per hectare is not necessary. Higher application of fertilizer may increase the costs and environmental risks.
    Keywords: Behrang cultivar, Chamran cultivar, Grain yield
  • M. Gorzin, F. Ghaderi, Far, E. Zeinali, S. E. Razavi Pages 611-622
    Introduction
    Soybean seed germination and seed vigor potential is lower compared with other crops, and it often greatly reduces at the planting time. The occurrence of unfavorable conditions during seed formation in field causes severe deterioration of seeds and reduces the seed quality. Planting date is one of the most important influencing factors on seed quality of soybean in field conditions. Since planting date affect seed quality by changing the environmental conditions including temperature, relative humidity and rainfall during seed development and maturation.
    Materials And Methods
    To evaluate the seed germination and seed vigor of soybean seeds wshich were obtained from various planting dates, a field experiment was conducted with a split plot arrangement in a randomized complete block design in three replications in Gorgan University of Agricultural Sciences and Natural Resources in 2011. Main plot included five planting dates April 20, May 13, June 3, June 29 and July 22, and sub plot consisted of three cultivars (Williams, Sahar and DPX). About 50 plants were selected and harvested during R7 (physiological maturity stage) from each plot, and their pods were removed by hand. Then, pods were dried in shade. To avoid mechanical damage, the seeds were removed by hand from the pods. Ultimately, seed quality was assessed by seed germination and seed vigor including accelerated aging, seedling growth rate (SGR) and electrical conductivity tests.
    Results And Discussion
    According to obtained results, the use of different planting dates caused the change at the beginning and ending time of seed filling period (R5-R7) of all three cultivars. This event in turn leads to creation different conditions in terms of temperature, rainfall and relative humidity during seed filling period in all three cultivars. Therefore Williams cultivar coincided with high temperatures more than two other cultivars, especially in the early planting dates. While DPX that was serotinous, encountered with lower temperatures and higher relative humidity. Sahar cultivar that in terms of the maturity group is between these two cultivars, in early planting dates encountered with lower temperatures compared to Williams and encountered with higher temperatures compared to DPX. Generally, the air temperature during seed filling period was lower by delay in planting. Planting date had a significant effect on seed germination and seed vigor, too. Seed Germination of two cultivars including Williams and Sahar fixed above 90 percent in four planting dates, but it significantly decreased in the planting date April 20 in Williams and July 22 in Sahar. Planting date affected seed germination of DPX. Accelerated aging and electrical conductivity tests similarly showed that the early spring planting dates reduced seed vigor of three cultivars, because it occurred when the high temperatures during seed filling period. Seed vigor of three cultivars increased with delays in planting, but due to occurrence of very low temperature and high rainfall during seed development in planting date of July 22, seed vigor of Sahar and DPX were reduced. In this study air temperature decreased and relative humidity increased during seed filling period of three cultivars with delay in planting. This issue led to lower seeds vigor in early spring planting dates compared to late planting dates due to collision of seed filling period with high temperatures. Of course germination and vigor of seeds produced in early planting dates in Sahar and DPX has always been higher than the seed germination and vigor of Williams. This was due to the absence of very high temperatures during seed filling period in these two cultivars. Because the seed filling period and maturity in Sahar and DPX occurred later than seed filling period and maturity of Williams. So that the mean maximum temperature during seed filling period of two cultivars Sahar and DPX in all planting dates was always less than Williams. On the other hand, since Williams was precocious, when that long delay occurred in planting date (July 22), matured before the occurrence of cold, wet and high rain conditions in autumn, and escaped from unfavorable conditions at the end of growing season. But Sahar and DPX were forced to deal with such conditions, and therefore their seeds produced in last planting date had a lower quality.
    Conclusions
    In summary, this study revealed that planting date with changes in environmental conditions during seed filling period (R5-R7) has a significant impact on soybean seed germination and seed vigor, and it is not considered in soybean fields in Golestan province. It was also noted that the choice of suitable planting date for the production of seeds with high quality, must be implemented according to the cultivar maturity group. Therefore, it is recommended that to produce high-quality seeds in precocious cv. Williams, planting operations must be carried out in July and avoided the early spring planting dates. In the case of serotinous cultivars like Sahar and DPX, it is better that planting operations performed in June, or at the beginning of July, and avoid any the excessive delay in theirs planting.
    Keywords: Accelerated aging test, Electrical conductivity test, Seed quality
  • F. Mardani, H. Balouchi, A. Yadavi, A. Salehi Pages 623-636
    Introduction
    Due to population growth and food shortage agricultural production is on increasing demand. In this order increasing cultivation area and yield per unit area are two ways of obtaining higheragricultural production (20). There is another important way that without incurring additional costs and use of water and fertilizer could result in higher production. This approach is increasing agricultural production per unit area by growing more than one crop in a year. Intercropping will be successful when competition for sources issless than competition within a species. Plants in the mixture can be chosen in a way that a species benefits from environmental changes caused by other species in mixed cultures directly (7, 15). Intercropping inhibits the growth and development of weeds and leads to increased production. Since the system will reduce the pesticide use, environmental pollution will be also less proportionally (37).
    Materials And Methods
    In order to evaluate the yield, yield components and potential weeds control under intercropping fenugreek and anise, an experiment was carried out based on a randomized complete block design with three replicationsat the Agricultural Research Field of Yasouj University during growing season of 2012-2013. Treatments included pure cultures of fenugreek and anise, single-row, double-row and three-tier intercropping of fenugreek and anise at no weed control and weed control conditions.
    Results And Discussion
    The results showed that different intercropping treatments had significant effects on pod number per plant, grain weight and grain and biological yield of fenugreek and also, on number of lateral branches, number of grains per plant and grain and biological yield of anise. There were nosignificant effects on plant height, number of lateral branches, number of grain per pod, harvest index of fenugreek, as well as plant height, number of umbel let per plant, seed weight and harvest index of anise. The lowest weed dry weight was observed in two rows intercropping and the maximum dry weight of weeds in fenugreek monoculture, respectively. Evaluation of land equivalent ratio showed that intercropping of fenugreek and anise is superior to pure culture and single-row intercropping had highest land equivalent ratio (1.39). Index values of the actual yield loss were also positive, which indicates the usefulness of mixed culture compared to monoculture of each plant. Among the different treatments tested AYL's highest were allocated by single-row intercropping treatments in the absence of weed. AYL minimum belonged to two rows intercropping treatments and without weed. All positive values of AYL indicated the utility of intercropping. Therefore it can be concluded that intercropping in all proportions, combined with the principle of protection, is benefiial. The effect of weed control on grain yield in the absence of fenugreek was observed in single-row, double and triple rows cultivation without weed control, respectively. This resulted in a decrease of 3%, 21% and 18% yield, and indicates a greater impact of single row cultivation on the weed control. It speculated that the higher nitrogen fixation under the triple rows may help higher weed growth.
    Conclusions
    Results showed that higher yield in treatments of intercropping compared to pure culture. Other indicators also showed the utility of intercropping, mixed farming profitability. In this study for all treatments, intercropping, and land equivalent ratio was greater than single cultivation. Thus achieving higher LER than one indicates that mixed cultures compared with pure cultures of environmental resources, such as light and nutrients more effectively used as components of mixed cultures were complementary. This advantage is due to physiological and morphological differences between the components that are in mixed cultures. It seems to increase the diversity of crop species and increases the competition between crops and weed species, more efficient allocation of resources and their distribution among crop species occurs, resulting in reduced weed infestation. Absorption of light by a dense canopy of intercropping, reduces the amount of light loss by the canopy and thus reduces weed growth and seed germination. Fenugreek and anise single-row intercropping is better than pure cropping.
    Keywords: Actual yield loss, Essential oil, Land equivalent ratio, Mix crop, Weed
  • Kh Parvizi, Ali Ghadami, Firooz Abadi Pages 637-650
    Introduction
    Water deficiency is the main factor that limits crop production in arid and semiarid regions. Due to limitation in water resources, low efficiency of water in surface irrigation method and irregular rainfall application of sprinkle and triple irrigation methods is inevitable in more regions of Iran. In this respect, it is crucial to employ methods that can improve water use efficiency and do not damage the sustainable production of potato in these regions. Introduction of some potato cultivars that have good capability of yield in deficit irrigation is anopportunity in this case. In previous study new released potato cultivar (Savalan) and three other promising clones had more yield and growing potential compared with Agriacultivar. Therefore, it was necessary to evaluate new cultivar (Savalan) and promising clones in water deficit irrigation. In this respect, as is expected, if cultivars or clones have more tolerance to water deficit they canbe suitable cultivar candidate and germplasms in water critical water conditions in many regions of Iran.
    Material And Methods
    This experiment has been conducted in Agricultural and Natural Resources Research Center of Hamedanin split plot design based on Randomized Complete Block in three replications with two factors, including: 1. Water deficit irrigation treatment, 50, 60, 70, 80, 90 and 100% of regular potato irrigation requirement. 2. Three clones accompanied with Savalan and Sante Cultivars. Irrigation system was tape method. Irrigation treatments were established immediately after cultivation of tubers. Water requirement was calculated through corrected vapotranspiration (ETo) determined by Penman-Monteith equation considering 90% water use efficiency. During the growing season, fewgrowing indices including, flowering longevity and harvesting time were recorded along with measurement of dry and fresh root weights. Total yield was measured by selecting randomly of 2 m2in every plot. Harvested tubers were separated as marketable and non-marketable. Reducing sugars of tuber were calculated by titration and volume accuracy method. Tow-way analysis of variance (ANOVA) of the data was carried out using SAS software and the means were compared through the Duncan’s Multiple Range Test.
    Results And Discussion
    multiple analysis of variance of two years demonstrated that water treatment and clone effects were significant at 1% α level on number of stem, time and longevity of flowering, overlapping time, senescing time, fresh and dry root weight, unmarketable yield and total yield. Water regimes had significant effect on reducing sugars but cultivar had not the same effect. Means comparison of main stem showed that providing 80% water requirement had uppermost effect (No average of 6.16 per plant), since it didn’t significant difference with 90% and 100% of water requirement. Canopy overlapping time delayed as water supplement decreased. Three clones and Savalan showed similar reaction, but differences were significant as compared with other cultivar (Sante).It seems that supplementing of water requirement as 70% and upper than that have intensified the effect of cultivar on time of flowering and its longevity. Mean comparison of fresh and root dry weight showed significant effect of interaction between cultivar and irrigation levels. 397008-2 clone had more fresh and dry root weight in all irrigation levels as compared to other clones and cultivar. Mean comparison showed that 50 and 60 percent of water requirement increased in tuber. Three higher levels of irrigation regimes (80, 90 and 100 percentage of water requirement) showed the same effect on reducing sugar of tubers and didn’t show significant difference with each other. Supplying water requirement (100%) produced highest yield (6.25 kg m-2) and didn’t show significant with 80 and 90 percent of water supplement. In this research, there were different reaction between clone/cultivar in main stem and overlapping time for different irrigation regimes. The differences of flowering dateand its longevity between clones in different water treatments demonstrated that although flower longevity of potato is a qualitative trait related to cultivar inherit but it can be affected by environment condition like temperature, light intensity and soil moisture. In this research there have been remarkable changes in reducing sugar of tubers under different irrigation levels. Therefore we can conclude that by determining good strategy for water use management in potato, both water stresses and higher reduction of sugar can be avoided. This result was consistent with previous studies (12, 14 and 18) that evaluated the effect of water stress and water deficiency on qualitative characters of potato. Decreasing 20 percent water requirement of potato, resulted only 0.7 kg decrease of total yield per square meter. As a result, it can be save more than 40 million cubic meter of water only in Hamedan state every year. Moreover, if we apply some suitable cultivars same as Savalan and other promising clones that have more tolerance to water deficit, it can be more efficient.
    Conclusions
    Totally, the result of the this research showed that decreasing water requirement of potato until 20% not only did not impair the growth and performance of potato but also did not show adverse effects on qualify of harvested tuber. It is also found that Savalan and two clone had more advantage in comparison with others.
    Keywords: Water stress, Irrigation treatment, Potato, Yield, growth reaction