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تنشهای محیطی در علوم زراعی - سال دهم شماره 4 (زمستان 1396)

مجله تنشهای محیطی در علوم زراعی
سال دهم شماره 4 (زمستان 1396)

  • تاریخ انتشار: 1396/11/14
  • تعداد عناوین: 14
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  • سعید نواب پور *، ابراهیم هزارجریبی، ابوالفضل مازندرانی صفحات 491-503
    به منظور ارزیابی مقدار روغن و پروتئین دانه ده ژنوتیپ سویا در شرایط تنش خشکی در استان گلستان، آزمایشی به صورت کرت های خردشده در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه آزمایشی مرکز تحقیقات گرگان اجرا شد. فاکتور اصلی شامل زمان آبیاری با سه سطح مشتمل بر تیمار شاهد بر اساس تبخیر به میزان 50 میلی لیتر از تشتک تبخیر کلاس A، آبیاری در شرایط تنش متوسط و شدید به ترتیب بر اساس 100 و 150 میلی لیتر تبخیر از تشتک تبخیر بود. اعمال تنش آبی در زمان استقرار کامل گیاه آغاز گردید. فاکتور فرعی ژنوتیپ، شامل ده رقم و لاین سویا (DPX، ساری، Williams، Sahar، WE6،L17، HT2، Ds2، PE10 و DW1) بود. صفات مورد ارزیابی (مقدار روغن، مقدار پروتئین، عملکرد و اجزاء) در پایان دوره رشد اندازه گیری شدند. همچنین اجزای عملکرد شامل تعداد شاخه فرعی، تعداد غلاف، تعداد دانه در غلاف و وزن صد دانه نیز تعیین گردیدند. میزان وزن خشک بوته و عملکرد بر اساس تک بوته نیز اندازه گیری شدند. نتایج نشان داد که میزان عملکرد دانه با اجزای عملکرد همبستگی مثبت و معنی داری داشته و مقدار آن تحت تنش خشکی کاهش یافت. در این میان میزان کاهش صفات درصد وزن خشک بوته، وزن هزار دانه و ارتفاع بوته بیشتر از سایر صفات بود. وقوع تنش خشکی با تاثیر منفی بر اجزای عملکرد نهایتا سبب کاهش عملکرد دانه گردید. با توجه به وجود همبستگی مثبت و معنی دار بین میزان عملکرد دانه و وزن هزار دانه و کاهش قابل توجه میانگین وزن دانه در هر دو سطح تنش (تیمار 100 و 150)، می توان گفت که مقدار زیادی از کاهش عملکرد دانه ناشی از کاهش وزن هزار دانه بوده است. درصد پروتئین دانه با عملکرد رابطه منفی داشت و تحت تنش خشکی افزایش یافت. این مقدار افزایش در ژنوتیپ های مختلف متفاوت بود. درصد روغن در سطوح کم تنش خشکی افزایش یافت اما مقدار این افزایش معنی دار نگردید، ولی تنش شدید باعث کاهش درصد روغن شد. به طورکلی رابطه بین درصد روغن و پروتئین دانه منفی بود و ارقامی که درصد روغن بالایی داشتند مقدار درصد پروتئین آن ها پایین بود. در این میان تنها لاین HT2 عکس این مسئله را نشان داد و مقدار روغن و پروتئین دانه آن تحت تنش افزایش بیشتری یافت. لاین های PE10 و Ds2 بیشترین میانگین عملکرد دانه و رقم ساری کمترین عملکرد دانه را در بین ژنوتیپ های موردمطالعه نشان دادند.
    کلیدواژگان: پروتئین دانه، تنش خشکی، سویا، عملکرد، محتوای روغن
  • علی سلیمانی* صفحات 505-519
    به منظور بررسی اثر تنش خشکی بر برخی از شاخص های فیزیولوژیک رشد ارقام آفتابگردان مطالعه ای به صورت کرت های خردشده در قالب طرح پایه بلوک های کامل تصادفی با سه تکرار در منطقه مهیار شهرضای استان اصفهان اجرا شد. تنش خشکی در سه سطح آبیاری پس از تبخیر 80، 150 و 180 میلی متر از تشت تبخیر کلاس A به ترتیب به عنوان عدم تنش، تنش ملایم و شدید، در کرت های اصلی و چهار رقم آفتابگردان آذر گل، یوروفلور، قاسم و فرخ در کرت های فرعی قرار گرفتند.در این بررسی وزن خشک کل، شاخص سطح برگ، سرعت اسیمیلاسیون خالص و سرعت رشد گیاه مورد ارزیابی قرار گرفتند و نتایج نشان داد ماده خشک کل و شاخص سطح برگ با افزایش شدت تنش خشکی از 80 به 180 میلی متر تبخیر از تشت تبخیر کلاس A به طور معنی داری کاهش یافتند. بیشترین ماده خشک کل توسط تیمار 80 میلی متر تبخیر از تشت تبخیر حاصل شد که اختلاف آن با تیمار 150 میلی متر معنی دار نبود. در طی فصل رشد بیشترین میزان ماده خشک کل، شاخص سطح برگ و سرعت رشد محصول توسط تیمار 80 میلی متر تبخیر از تشت تبخیر حاصل شد. رقم آذر گل وزن خشک کل، سرعت رشد محصول و سرعت رشد نسبی بیشتری نسبت به سایر ارقام تولید نمود و به دلیل سطح برگ مناسب تر، سرعت اسیمیلاسیون خالص بالایی داشت. لذا تحت شرایط مشابه با مطالعه حاضر در شرایط عدم تنش خشکی تیمار آبیاری 80 میلی متر و در صورت بروز تنش خشکی ملایم تیمار آبیاری 150 میلی متر تبخیر از تشت تبخیر کلاس A و رقم آذر گل مناسب به نظر می رسد.
    کلیدواژگان: سرعت اسیملاسیون خالص، سرعت رشد محصول، شاخص سطح برگ، وزن خشک کل
  • ژاله زارعی، حسن حیدری* صفحات 521-530
    خشکی مهم ترین عامل محدودکننده تولید گیاهان زراعی در مناطق خشک و نیمه خشک است. به دلیل کاهش بارندگی، گرم شدن سطح کره زمین و هدر رفتن مقدار قابل توجهی از آب های سطحی در اثر تبخیر، این پژوهش به منظور تعیین میزان مصرف آب در سامانه آبیاری فتیله ای در مقایسه با سامانه آبیاری متداول (آبیاری سطحی) و طراحی و عملیاتی کردن سامانه آبیاری فتیله ای در مزرعه انجام شد. این آزمایش در قالب طرح بلوک های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی دانشکده علوم و مهندسی کشاورزی دانشگاه رازی در سال 1394 اجرا شد.تیمارهای آزمایشی شامل، آبیاری معمولی به عنوان تیمار شاهد و آبیاری فتیله ای بود. نتایج نشان داد که آبیاری فتیله ای نسبت به آبیاری سطحی محتوای نسبی آب برگ، سطح برگ، ارتفاع بوته و ساقه اصلی بیشتری را دارا بود. ازنظر وزن مخصوص برگ تفاوتی بین سامانه های آبیاری وجود نداشت. همچنین آبیاری فتیله ای نسبت به آبیاری سطحی ازنظر مصرف آب کاراتر و ماده خشک بیشتری تولید کرد. علت احتمالا این است که سله خاک و خیس شدن سطح خاک در آبیاری فتیله ای کمتر است. دسترسی دائمی به آب و عدم شرایط غرقابی هم می تواند رشد گیاه را بهبود ببخشد و کارایی مصرف آب و تولید ماده خشک را افزایش دهد.
    کلیدواژگان: آبیاری زیر سطحی، بهره وری آب، زیست توده، محتوای رطوبت نسبی برگ
  • سعید رضا حسین زاده، حمزه امیری *، احمد اسماعیلی صفحات 531-545
    کود آلی ورمی کمپوست می تواند نقش مهمی در رشد و تغذیه گیاهان ایفا کند. استفاده از آن می تواند اثرات منفی ناشی از تنش های محیطی را کاهش دهد. در این راستا، به منظور بررسی اثر کود ورمی کمپوست برخصوصیات مورفولوژیکی و غلظت عناصر برگ و ریشه گیاه نخود (رقم پیروز) در شرایط تنش کم آبی آزمایشی به صورت فاکتوریل در قالب طرح کاملا تصادفی با سه تکرار در دانشگاه صنعتی خاتم الانبیاء بهبهان به اجراء درآمد. دو فاکتور مورد آزمایش عبارت بودند: کود آلی ورمی کمپوست با 4 سطحشامل شاهد (بدون کاربرد ورمی کمپوست)، 10، 20 و 30 درصد و عامل کم آبی شامل بدون تنش کم آبی (100 درصد ظرفیت زراعی)، تنش کم آبی ملایم (75 درصد ظرفیت زراعی) و تنش کم آبی شدید (25 درصد ظرفیت زراعی) اعمال شد. نتایج نشان داد که در شرایط بدون تنش، کود ورمی کمپوست منجر به افزایش معنی دار تمامی صفات مورد بررسی شد. در شرایط تنش ملایم، کاربرد ورمی کمپوست به صورت معنی داری ارتفاع بوته، تعداد برگ و غلاف در گیاه، وزن خشک ریشه، طول، سطح و حجم ریشه، غلظت پتاسیم و کلسیم در برگ و ریشه را افزایش داد. در شرایط تنش شدید، افزودن ورمی کمپوست به خاک منجر به افزایش معنی دار تعداد برگ و غلاف در گیاه، قطر ریشه، غلظت پتاسیم و کلسیم در برگ و ریشه شد. بر طبق نتایج این مطالعه، استفاده از مخلوط کود ورمی کمپوست و خاک به منظور بهبود شرایط تنش کم آبی توصیه می شود.
    کلیدواژگان: تنش خشکی، خصوصیات رشدی، عناصر مغذی، کودهای آلی
  • حسین سرتیپ *، علیرضا سیروس مهر صفحات 547-558
    استفاده از اسید سالیسیلیک برای کاهش صدمات ناشی از تنش خشکی و بهبود شاخص های فیزیولوژیکی گیاه در مناطق خشک و نیمه خشک از مدیریت های مفید جهت کشت گیاهان دارویی ازجمله زیره سبز است. ازاین رو آزمایشی به صورت کرت های خردشده بر پایه طرح بلوک های کامل تصادفی شامل سه سطح فراهمی آب، 50 (شاهد)، 100 و 150 (تنش خشکی) میلی متر تبخیر از تشتک تبخیر کلاس A به عنوان عامل اصلی ومحلول پاشی اسید سالیسیلیک (صفر به عنوان شاهد، 1 و 3 میلی مولار) به عنوان عامل فرعی در سه تکرار انجام گردید. نتایج نشان داد که سطوح مختلف فراهمی آب، اسید سالیسیلیک و اثر متقابل آن ها بر رشد و نمو گیاه زیره سبز موثر بودند.تنش خشکی سبب کاهش میزان رنگیزه کلروفیل a گردید، درحالی که میزان پرولین و کربوهیدرات را افزایش داد. کاربرداسید سالیسیلیک باعث افزایش صفاتی مانند رنگ دانه های فتوسنتزی و هیدرات های کربن گردید. اثر متقابل فراهمی آب و اسید سالیسیلیک بر تمامی صفات به جز هیدرات کربن و کلروفیل a معنی دار شد و بیشترین عملکرد دانه (98.9 گرم در مترمربع) در تیمار انجام آبیاری پس از 50 میلی متر تبخیر از تشتک و محلول پاشی 1 میلی مولار اسید سالیسیلیک به دست آمد. با توجه به مشاهدات این تحقیق می توان نتیجه گرفت که استفاده از اسید سالیسیلیک راهکاری مناسب به منظور افزایش مقاومت گیاه زیره سبز در برابر تنش خشکی است.
    کلیدواژگان: پرولین، تشتک تبخیر، رنگیزه فتوسنتزی، عملکرد دانه، کلروفیل a
  • مرضیه فارسی، فرزین عبدالهی*، امین صالحی، شیوا قاسمی صفحات 559-570
    به منظور بررسی واکنش فیزیولوژیکی گیاه دارویی مرزنجوش (Origanum majorana) به عنصر روی در شرایط تنش خشکی، آزمایشی به صورت فاکتوریل در قالب طرح کاملا تصادفی با 3 تکرار در سال 1393 در گلخانه تحقیقاتی دانشگاه هرمزگان اجرا گردید. فاکتورهای آزمایش شامل سطوح مختلف تنش خشکی (رطوبت خاک معادل 50، 75 و 100% ظرفیت زراعی) محلول پاشی کود روی (غلظت های 0، 1 و 3 در هزار) بودند. نتایج تجزیه واریانس نشان داد که تنش خشکی اثر معنی داری بر تمام صفات به غیراز درصد اسانس داشته و تیمار کود روی در تمام صفات اندازه گیری شده به غیراز کلروفیل a و آنزیم کاتالاز اثر معنی داری داشته است. اثر متقابل روی و تنش خشکی بر میزان کلروفیل a، b، کل، میزان آنتوسیانین و درصد اسانس معنی دار بود. اعمال تنش معادل 75% ظرفیت زراعی موجب افزایش کلروفیل a، b و کل گردید درحالی که تنش 50% ظرفیت زراعی موجب افزایش میزان کاروتنوئید، قند محلول، آنتوسیانین و آنزیم کاتالاز گردید. محلول پاشی غلظت سه در هزار روی موجب افزایش میزان کلروفیل b و کل و محلول پاشی غلظت یک در هزار روی نیز موجب افزایش میزان قند محلول و درصد اسانس گردید. در شرایط تنش 75 و 100% ظرفیت زراعی، محلول پاشی یک در هزار روی موجب افزایش میزان کلروفیل a، b، میزان آنتوسیانین و درصد اسانس شد. هرچند در این آزمایش آنزیم کاتالاز تحت تاثیر تیمارهای روی قرار نگرفت اما محلول پاشی با غلظت پایین روی از طریق افزایش بیوسنتز کلروفیل، کارتنوئید، آنتوسیانین و قند محلول باعث افزایش تحمل گیاه مرزنجوش و درنتیجه بهبود شرایط رشدی این گیاه در شرایط تنش خشکی شد.
    کلیدواژگان: اسانس، ظرفیت زراعی، گیاهان دارویی، محلول پاشی کود
  • حمیدرضا فلاحی*، مرتضی قربانی، مهسا اقحوانی شجری، علیرضا صمدزاده، مهدی خیاط، زهرا مرکی، امیرحسن اسعدیان صفحات 571-582
    در این تحقیق تاثیر فراهمی آب (آبیاری پس از تبخیر 100 و 200 میلی متر از تشتک کلاس A به ترتیب به عنوان تیمارهای بدون تنش و تحت تنش خشکی)، تلقیح میکوریزایی (شاهد، Glomus intraradicesو Glomus versiforme) و مصرف اسید هیومیک (صفر و 4 کیلوگرم در هکتار) بر عملکرد و مولفه های رنگ در کاسبرگ های گیاه دارویی چای ترش مورد بررسی قرار گرفت. برای این منظور آزمایشی به صورت کرت های دو بار خردشده بر پایه طرح بلوک های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی دانشکده کشاورزی سرایان (دانشگاه بیرجند) انجام شد. عملکرد کاسبرگ در شرایط اعمال تنش خشکی کمتر از تیمار عدم وجود تنش (به ترتیب 10.7 و 19.1 گرم در مترمربع) و در شرایط تلقیح با قارچ میکوریزای Glomus intraradices بیشتر از تیمار عدم تلقیح میکوریزایی بود (به ترتیب 18.2 و 12.9 گرم در مترمربع). همچنین مصرف هیومیک اسید در شرایط اعمال تنش خشکی عملکرد کاسبرگ خشک را بهبود بخشید. تنش خشکی موجب کاهش مقدار a*، هیو وکرما به ترتیب به میزان 22، 53 و 15 درصد شد. مصرف اسید هیومیک نیز مقدار زاویه هیو را 63 درصد کاهش و نسبت b/a را 25 درصد افزایش داد. هر دو گونه میکوریزا حدود 66 درصد شاخص هیو را در مقایسه با تیمار شاهد افزایش دادند. نتایج اثرات سه گانه عامل های آزمایشی نشان داد که بیشترین و کمترین میزان b/a به ترتیب در تیمارهای تنش خشکی× مصرف اسید هیومیک× تلقیح میکوریزایی و عدم تنش× عدم مصرف هیومیک× عدم تلقیح به دست آمد (به ترتیب 0.19 و 0.02). همچنین بیشترین میزان هیو (o215) در شرایط عدم اعمال تنش خشکی × عدم مصرف اسید هیومیک و تلقیح با Glomus versiformeحاصل شد. بیشترین میزان شاخص قرمزی نیز در تیمار عدم وقوع تنش خشکی × عدم کاربرد اسید هیومیک × انجام تلقیح میکوریزایی مشاهده شد. افزون بر این، همبستگی معنی داری بین a* با کروما (**0.64+) و شاخص قهوه ای شدن (**0.71-) و نیز بین هیو با شاخص قرمزی (**0.68+) به دست آمد. درمجموع، عملکرد و کیفیت رنگ کاسبرگ چای ترش در شرایط عدم وقوع تنش خشکی مناسب تر بود و تلقیح میکوریزایی توانست تا حدودی اثرات منفی تنش خشکی بر عملکرد و شاخص های رنگ کاسبرگ را کاهش دهد.
    کلیدواژگان: روشنایی، زاویه هیو، کروما، کم آبیاری، گیاه دارویی
  • یعقوب عارفی، الناز فرج زاده معماری تبریزی * صفحات 583-593
    تنش رطوبتی مهم ترین تنش غیرزیستی با اثر نامطلوب بر رشد و عملکرد گیاهان است بااین وجودانتخاب رقم مناسب و انجام پرایمینگ بذر موجب تعدیل اثر نامطلوب تنش رطوبتی بر رشد و نمو گیاهان می شود. هدف این پژوهش ارزیابی تاثیر هم زمان مدت زمان پرایمینگ (صفر (عدم پرایمینگ)، 8، 16 و 24 ساعت) و دو رقم ذرت (706 و 604) تحت سه شرایط رطوبتی (انجام آبیاری پس از 70، 110 و 150 میلی متر تبخیر از تشتک تبخیر کلاس A) و در سه تکرار و به صورت اسپلیت فاکتوریل و بر پایه طرح بلوک های کامل تصادفی بود. بین ارقام ازنظر عملکرد دانه اختلاف معنی داری مشاهده نشد. تنش رطوبتی تاثیر قابل توجهی در کاهش عملکرد ارقام داشت، به طوری که در صورت عدم پرایمینگ، آبیاری پس از 150 میلی متر تبخیر از تشتک تبخیر کاهشی 52 درصدی را در عملکرد دانه در مقایسه با آبیاری پس از 70 میلی متر تبخیر باعث شد. بااین وجود پرایمینگ بذرهای ذرت با مدت زمان های بالاتر از 16 ساعت از این کاهش عملکرد ناشی از کم آبی جلوگیری نمود. در صورت عدم پرایمینگ، پرایمینگ 8 و 16 ساعت، تیمار آبیاری پس از 110 میلی متر تبخیر از تشتک تبخیر تاثیری بر عملکرد دانه نداشت. کم آبی شدید وزن بلال، وزن خشک اندام هوایی، محتوای کلروفیل برگ، سطح برگ و ارتفاع بوته را نیز نسبت به شاهد به ترتیب 20.7، 21.9، 14.9، 42.9 و 10.6 درصد کاهش داد. پرایمینگ تاثیر مثبت قابل توجهی را بر صفات موردبررسی داشت و پرایمینگ 8 ساعت باعث افزایش 19.9، 15.3 و 19.2 درصدی سطح برگ، وزن اندام هوایی و تعداد دانه شد، ولی بسته به زمان تیمار اثر پرایمینگ متفاوت بود. در کل پرایمینگ های 8 و 16 ساعت موثرترین مدت زمان های پرایمینگ ازنظر عملکرد دانه بودند.
    کلیدواژگان: تعداد دانه، جوانه زنی، عملکرد، Zea mays
  • محمدرضا رمضانی، محمد جواد ثقه الاسلامی*، محمدحسن سیاری زهان، سید غلامرضا موسوی صفحات 595-604
    به منظور بررسی اثر شوری آب آبیاری و محلول پاشی روی و آهن بر زنیان آزمایشی به صورت طرح کرت های خردشده در قالب بلوک های کامل تصادفی با سه تکرار در دشت خضری استان خراسان جنوبی در سال 1389 انجام شد. تیمارهای شوری شامل سه نوع آب از سه چاه عمیق با شوری های 970، 3500 و 7700 میکرو زیمنس بر سانتی متر به عنوان کرت اصلی و تیمارهای محلول پاشی (شاهد، محلول پاشی آهن با غلظت 3 در هزار، محلول پاشی روی 4 در هزار و محلول پاشی آهن + روی) به عنوان کرت فرعی در نظر گرفته شد. نتایج نشان داد شوری به طور معنی داری سبب کاهش عملکرد بذر و اسانس و ویژگی های مورفولوژیکی (به جز تعداد چترک در چتر) شد، اما اثر معنی داری بر درصد اسانس بذر نداشت. بیشترین عملکرد بذر (236 گرم بر مترمربع)، عملکرد اسانس (8.578 گرم بر مترمربع)، ارتفاع بوته (74.8 سانتیمتر)، تعداد شاخه در بوته (10.8) و تعداد چتر در بوته (236.3) مربوط به تیمار شوری کم (970 میکروزیمنس بر سانتیمتر) بود. تیمارهای محلول پاشی اگرچه بر عملکرد بذر و درصد و عملکرد اسانس بذر اثر معنی داری نداشتند، اما اثر متقابل آن ها با تیمارهای شوری بر عملکرد بذر و اسانس معنی دار شد، به طوری که بیشترین عملکرد بذر و اسانس مربوط به تیمار شوری کم و محلول پاشی با آهن بود. این در حالی است که در شرایط شوری زیاد محلول پاشی آهن و روی اثر معنی داری بر عملکرد بذر و اسانس نداشت. به طورکلی به نظر می رسد واکنش زنیان به محلول پاشی عناصر آهن و روی بسته به شوری آب آبیاری متفاوت است.
    کلیدواژگان: ارتفاع، اسانس، چتر، ریزمغذی، شاخه زنی
  • فردین قنبری، فخرالدین صالحی، محمد سیاری * صفحات 605-614
    دمای پایین منجر به آسیب های فیزیولوژیکی به سلول گیاهان حساس به سرمازدگی و از بین رفتن محصولات گرمسیری و نیمه گرمسیری می شود. در این مطالعه مدل سازی شبکه عصبی مصنوعی به منظور پیش بینی اثر تنش سرما بر نشاء گوجه فرنگی بعد از اعمال پیش تیمار خشکی با 0، 10 و 20 درصد پلی اتیلن گلیکول استفاده گردید. امکان افزایش تحمل تنش سرمایی در نشاهای گوجه فرنگی با کاربرد پلی اتیلن گلیکول بررسی و پس از اعمال تنش سرما به مدت 6 ساعت در روز به مدت6 روز متوالی و در دمای 3 درجه سلسیوس، داده ها جمع آوری گردید. به منظور پیش بینی اثر تنش سرما بر خصوصیات نشاء گوجه فرنگی از شبکه عصبی پرسپترون چندلایه پیش خور با 2 ورودی (اثر تنش خشکی و اثر تنش سرمایی) و 8 خروجی (کلروفیل a، کلروفیل b، فنل کل، محتوای آب نسبی، فلورسانس کمینه، فلورسانس بیشینه، نشت یونی ریشه و پرولین) استفاده شد. نتایج نشان داد شبکه ای با تعداد 7 نرون در یک لایه پنهان و با استفاده از تابع فعال سازیتانژانت هیپربولیکو روش بهینه سازی لیونبرگ مارکوت و درصد داده های مورداستفاده برای تربیت/ آزمون/ ارزیابی برابر 40/20/40 می توان اثر تنش خشکی بر میزان مقاومت به سرمای نشاهای گوجه فرنگی را با میانگین ضریب همبستگی برابر 0.92 تخمین زد. بر اساسنتایج آنالیز حساسیت توسط شبکه عصبی بهینه، شدت تنش خشکی اعمال شده با پلی اتیلن گلیکول موثرترین عامل در تخمین تحمل به سرما و خصوصیات فیزیولوژیکی گوجه فرنگی می باشد.
    کلیدواژگان: پرولین، فلورسانس بیشینه، فنل کل، کلروفیل
  • محسن طریق الاسلامی، محمد کافی*، احمد نظامی، رضا ضرغامی صفحات 615-625
    به منظور بررسی تاثیر اسید سالسیلیک بر تخفیف اثرات تنش سرمازدگی و خشکی بر عملکرد سینگل کراس 400ذرت، آزمایشی به صورت کرت های دو بار خردشده در قالب طرح بلوک کامل تصادفی در سه تکرار در گلخانه و مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد در سال 1394اجرا شد. عامل اصلی تنش سرما در دو سطح (عدم تنش سرمازدگی و تنش سرمازدگی به مدت 12 ساعت در دمای 5 درجه سانتی گراد در مرحله چهار برگی)، عامل فرعی شامل سه سطح آبیاری (100، 75 و 50 درصد نیاز آبی گیاه) و عامل فرعی فرعی محلول پاشی با اسید سالسیلیک (عدم محلول پاشی (شاهد)، محلول پاشی 200 میکرو مولار و محلول پاشی 400 میکرو مولار) در نظر گرفته شدند. اولین زمان محلول پاشی قبل از اعمال تنش سرمازدگی در شرایط کنترل شده بود و پس از کشت گیاهان در مزرعه هر 15 روز یک بار تکرار شد. نتایج نشان داد تنش سرمازدگی اول فصل تاثیر معنی داری بر صفات موردبررسی نداشت. اثرات تنش خشکی و اسید سالسیلیک بر صفات مورد آزمایش معنی دار بود. اثرمتقاب لتنش خشکی و اسید سالسیلیک برعملکرد دانه،عملکردبیولوژیکی، شاخص برداشت، کارایی مصرف آب و بهره وری آب معنی دار بود. اثر اسید سالسیلیک بر بهبود رشد و افزایش عملکرد در هر دو شرایط تنش و غیرتنش معنی دار بود. بالاترین عملکرد دانه و بیولوژیک به ترتیب با میزان 8543 و 18220 کیلوگرم در هکتار مربوط به تیمار آبیاری مطلوب با محلول پاشی 400 میکرو مولار بود. درمجموع اسیدسالسیلیک باغلظت 400 میکرو مولار سبب بهبودعملکردذرتشد و اثرات منفی تنش های سرما و خشکی را بر عملکرد گیاه ذرت کاهش داد.
    کلیدواژگان: بهره وری آب، شاخص برداشت، عملکرد بیولوژیک، کارایی مصرف آب، نیاز آبی
  • احمد نظامی *، ابراهیم ایزدی دربندی، مریم جانعلی زاده قزوینی، روح الله حسن بیگی صفحات 627-639
    به منظور بررسی تحمل به یخ زدگی خاکشیر، آزمایشی به صورت فاکتوریل و در قالب طرح کاملا تصادفی با سه تکرار در سال 1387 در دانشگاه فردوسی مشهد انجام شد. تیمارهای آزمایش شامل اکوتیپ خاکشیر (در پنج سطح شامل اقلید، سبزوار، همدان، تربت جام و نیشابور) و دمای یخ زدگی (در 10 سطح شامل صفر تا 18- با فواصل دو درجه سانتی گراد) بود. گیاهان خاکشیر در پاییز کشت و تا مرحله پنج تا هفت برگی در آب و هوای طبیعی رشد داده شدند. سپس برای اعمال دماهای یخ زدگی به یک فریزر ترموگرادیان منتقل شدند. سه هفته بعداز اعمال تنش، درصد بقاء، دمای پنجاه درصد کشندگی بر اساس درصد بقاء (LT50su)، تعداد برگ، دمای کاهنده 50 درصد تعداد برگ (RNLT50)، تعداد گره، دمای کاهنده 50 درصد تعداد گره (RNNT50)، وزن خشک و دمای کاهنده 50 درصد وزن خشک (RDMT50) آن ها بررسی شد. نتایج نشان داد اکوتیپ همدان بیشترین درصد بقاء و اکوتیپ نیشابور کمترین درصد بقاء را دارند. در اکوتیپ های اقلید و نیشابور کاهش معنی دار درصد بقاء از دماهای بالاتری (10- درجه سانتی گراد) نسبت به اکوتیپ های همدان، سبزوار و تربت جام (12- درجه سانتی گراد) شروع شد. در دمای 12- درجه سانتی گراد، اکوتیپ های نیشابور و تربت جام کمترین تعداد برگ واکوتیپ های همدان و اقلید به ترتیب بیشترین و کمترین وزن خشک زیست توده را بعد از دوره بازیافت دارا بودند. همچنین در دمای 12- درجه سانتی گراد، تعداد گره در اکوتیپ همدان تقریبا 30 درصد نسبت به شاهد کاهش یافت، درحالی که این کاهش در اکوتیپ های اقلید و نیشابور بسیار بیشتر بود. در این آزمایش LT50su بین 10.2- تا 12.1- درجه سانتی گراد متغیر بود. رتبه بندی اکوتیپ های خاکشیر بر اساس شاخص های LT50su، RNLT50، RNNT50 و RDMT50 نشان داد که اکوتیپ های نیشابور و همدان به ترتیب حساس ترین و متحمل ترین اکوتیپ های خاکشیر نسبت به تنش یخ زدگی بودند
    کلیدواژگان: اکوتیپ، درصد بقاء، دمای پنجاه درصد کشندگی، وزن خشک، یخ زدگی
  • محمود عطارزاده*، حمیدرضا بلوچی، مجید رجایی، فرزانه پولادی صفحات 641-653
    اسید آبسیزیک یکی از هورمون‏های گیاهی است که نقش عمده‏ای در چرخه زندگی گیاه داشته و بسیاری از فرایندهای مهم فیزیولوژیکی ازجمله نمو و سازگاری گیاه به تنش‏های محیطی را تنظیم می‏نماید.اسید آبسیزیکاز طریق کنترل وضعیت آبی گیاه تحت تنش، اثرات زیان‏بار خسارت تنش گرما را به طور چشمگیری کاهش می‏دهد. این آزمایش به صورت فاکتوریل در قالب طرح بلوک‏های کامل تصادفی با سه تکرار در گلخانه دانشکده کشاورزی دانشگاه ولی عصر رفسنجان در سال 1392 انجام گرفت. فاکتور اول شامل پیش تیمار هورمون اسید آبسیزیک در 4 سطح صفر، 50، 100 و 200 میکرومولار و فاکتور دوم شامل اعمال تنش گرما با درجه حرارت 40 درجه سانتی‏گراد در 4 بازه‏ی زمانی صفر، 8، 16 و 24 ساعت بود که به گیاهچه های ذرت، هیبرید سینگل کراس 704 اعمال شدند. گیاهچه های ذرت قادر به تحمل تنش گرمایی 8 ساعت بودند و تاثیر منفی گرما با افزایش مدت زمان آن افزایش یافت که منجر به کاهش تولید ماده خشک اندام هوایی در تنش گرمایی 16 و 24 ساعته گردید. افزایش غلظت اسید آبسیزیک و تنش گرما باعث کاهش معنی‏داری در کلروفیل a ذرت گردید، به طوری که در شرایط گرمای 24 ساعته و غلظت 200 میکرومولار اسید آبسیزیک، با کاهش 9/36 درصدی نسبت به شاهد به دست آمد. همچنین تنش گرمای 24 ساعت سبب کاهش کارتنوئید به میزان 17 درصد نسبت به شاهد گردید. غلظت 50 و 100 میکرومولار اسید آبسیزیک، تا حدودی توانسته سبب کاهش نشت یونی برگ، افزایش محتوای نسبی آب و شاخص سبزینگی برگ ذرت شود، که درنتیجه سبب افزایش وزن خشک اندام هوایی ذرت در شرایط تنش گرما می‏گردد.
    کلیدواژگان: دمای برگ، ذرت، ماده خشک، محتوای نسبی آب
  • عبدالحسین رضایی، حمیدرضا بلوچی*، محسن موحدی دهنوی، ابراهیم ادهمی صفحات 655-671
    امروزه آلودگی خاک به فلزات سنگین درنتیجه فعالیت های انسانی یکی از تنش های محیطی مهم در گیاهان بوده، که می تواند به تولید گونه های اکسیژن فعال منجر شود. پرایمینگ با اسید جیبرلیک، اسید سالیسیلیک و نیترات پتاسیم به عنوان یک گزینه مناسب برای کاهش اثرات سمی کادمیوم در نظر گرفته شده است. این مطالعه با هدف بررسی اثر پرایمینگ بر برخی صفات فیزیولوژیکی گیاه و شاخص های کیفی بذر سورگم تحت تنش کلرید و نیترات کادمیوم در سال 1394 در دانشگاه یاسوج انجام شده است. آزمایش به صورت فاکتوریل در قالب طرح کاملا تصادفی در سه تکرار اجرا گردید. فاکتور اول شامل اسید جیبرلیک 800 میلی گرم در لیتر، اسید سالیسیلیک 0.3 میلی مولار، نیترات پتاسیم 1% و شاهد (بدون پرایم) و فاکتور دوم شامل سطوح کلرید و نیترات کادمیوم هرکدام در چهار سطح (0، 7.5، 15 و 30 میلی گرم در کیلوگرم خاک) بود. نتایج نشان داد که اثر متقابل کادمیوم و پرایمینگ برای پروتئین محلول در آب، آنزیم کاتالاز، آنزیم سوپر اکسید دیسموتاز و ارتفاع بوته معنی دار بود. اثر کادمیوم نشان داد که 30 میلی گرم کلرید کادمیوم به ازای هر کیلوگرم خاک وزن دانه را نسبت به شاهد 24 درصد کاهش داد. به طورکلی تمام سطوح کادمیوم نسبت به شاهد (بدون کادمیوم) اثر کاهنده بر روی وزن دانه داشتند. پرایمینگ بذر با 0.3 میلی مولار اسید سالیسیلیک منجر به افزایش سرعت جوانه زنی و شاخص طولی بنیه بذر سورگم تحت تنش کادمیوم گردید. همچنین بیشترین شاخص وزنی بنیه در 15 میلی گرم کلرید و نیترات کادمیوم به ازای هر کیلوگرم خاک مشاهده شد و کمترین شاخص وزنی بنیه به 7.5 و 30 میلی گرم کلرید کادمیوم به ازای هر کیلوگرم خاک تعلق داشت. در کل، پرایمینگ بذر با 800 میلی گرم در لیتر اسید جیبرلیک، و 0.3 میلی مولار اسید سالیسیلیک با بهبود شاخص های بیوشیمیایی و فیزیولوژیک گیاه مادر ازجمله افزایش محتوای پروتئین محلول و کلروفیل برگ می تواند باعث مقاومت نهال سورگم به سمیت کادمیوم و بهبود رشد آن و افزایش وزن دانه گردد. درنتیجه بذور تولیدی در این شرایط دارای سرعت جوانه زنی، شاخص بنیه بذر بیشتری نسبت به شاهد (عدم استفاده از پرایمینگ) هستند.
    کلیدواژگان: آنزیم های آنتی اکسیدان، جوانه زنی، اسید جیبرلیک، اسید سالیسیلیک، فلزات سنگین
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  • Saeed Navabpour *, Ebrahim Hezarjaribi, Aboulfazl Mazandarani Pages 491-503
    Soybean is an annual self-fertilized crop, belonging to leguminous family and glycine genus, with 40 chromosomes. Soybean is the most important oil crop worldwide since the composition of oil and protein which plays a significant role in public health. Soybean seeds have an average of 40 percent protein and 20 percent oil. Iran import more than 90% of edible oil annually. With 50 hectares of lands under soybean cultivation, Golestan province is the largest soybean cultivation area in Iran. The limitation of water is one of the serious problems in most cultivated lands. In order to solve this problem, relying on the genetic potential and identify drought tolerant varieties are most quick and economic ways. In this regard, pay attention to oil and protein content was quick valuable, which was considered in this study well. In order to evaluate the amount of oil and protein content as well as some related traits under drought stress conditions of soybean genotypes experiment carried out by using split plot format in randomized complete block design with three replications. Main factor was time-course of irrigation included three levels: FC irrigation (control), irrigation after50mm evaporation form a class evaporation pot, irrigation after 100mm evaporation form a class evaporation pot and irrigation after 150mm evaporation form a class evaporation pot. In each irrigation soil moisture to field capacity was reached. Water stress at the time of establishment of the plants began. Sub factor included 10 soybean genotypes: DPX, SARI, williams, Sahar, WE6, L17, HT2, Ds2, PE10 and DW1. Measured traits were included grain oil and protein content, grain yield, plant height, number of sub branches, number of pods, number of seed per pod, seed weight, and dry matter. The percentage of dry matter yield per plant were measured based. At the end of the growing period, to determine the percentage of protein and oil seed samples were taken from each treatment. The results showed that the grain yield and yield components had a significant positive correlation and its value fell under drought stress condition. The reduction of dry matter, seed weight and plant height was higher than other traits. The results of this study showed that the drought had negative impact on yield components which eventually comes to reduce of grain yield. In general, drought stress treatment at each level had more deteriorate effect on susceptible genotypes. Considering the significant positive correlation between seed yield and one thousand seeds weight and significant reduce seed weight in both stress levels (100 and 150 treatment), we can say that a lot of grain yield reduction was due to weight loss. In the meantime, more tolerant and better show for cultivation in areas with water shortages is more suitable. Interestingly, the amount of protein increased by effect of drought condition in most genotypes. It was the same for oil content just for 50mm drought treatment, while significant reduction occurred at 100mm and 150mm drought treatments. There was negative correlation between oil and protein content. PE10 and DS2 had the highest grain yield and sari variety had the lowest grain yield.
    Keywords: Drought stress, Grain protein, Oil content, Soybean, Yield
  • Ali Soleymani * Pages 505-519
    Introduction
    Sunflower is one of the most important oil crops which plays an important economical and agronomical role in crop rotation because of high oil quality. This crop is very flexible in bad environments. Water deficiency lessen net assimilation rate, dry weight of leaves, stem, and root and causes total dry weight and slow growth rate (Turrner and Sobrado 1987; Ren et al., 2016). Leaf area index is the most important growth index of sunflower which shows the highest sensitivity to water deficiency. Then, the main sign of water stress in vegetative phase of sunflower is reduction of number and size of leaves. Net assimilation rate Sunflower generally 10 to 20 days after germination increased or remained constant. Goksoy and Demir (2004)announced that restricted irrigation reduced leaf area index due to yellowing and falling leaves. Sunflower can reach to its maximum leaf area under full irrigation in proportion to water deficiency, water stress in vegetative phase caused shorter plants and lower dry matter of sunflower (Cox and Jolliff. 1986). This study was conducted to examine the effect of drought stress on growth properties of their sunflower cultivars in Isfahan (Iran).
    Materials And Methods
    The study was conducted in 2013 as split plot in randomized blocks design with three replications. Main plots were irrigation in four levels (80, 150 and 180 mm evaporation from evaporation pan class A) and sub plots were four sunflower cultivars (Azargol, Euroflor, Ghasem and Farrokh). Soil preparation was done and seeds were sown at June 8th. Every plot had five lines with six meter length, 60cm inter row space and 14cm distance between plants to reach to twelve plants per square meter. Irrigation was done according to 80mm evaporation until plant establishment and after that irrigation treatments were enforced. Sampling was done every 15 days and at the time of maturity considering marginal effects. In order to calculate trends of total dry matter, leaf area index, net assimilation rate, and crop growth rate the best regression equations were used (soleymani et al, 2003). MSTAT-C software and mean comparison with Duncan’s test in 5% probability were used.
    Results And Discussion
    The effect of irrigation on maximum leaf area index was significant. The highest leaf area index was obtained by irrigation after 80 mm evaporation from class A .There was a significant difference with the other irrigation treatments. Lowest LAI by irrigation after 180 mm evaporation from class A pan evaporation so irrigation treatments had significant differences with other results show that with increasing severity of drought stress the leaf area index decreased. It seems that water stress during vegetative growth to remain small leaves and leaf area index during the period of reduced crop.
    The effect cultivars on the leaf area index was significant. Most leaf by leaf area index by as much as Euroflor significantly different from that of other varieties. Lowest leaf area index was obtained by the Qasem. Aargol and Farrukh was not significantly different. The results showed that by reducing crop water requirement LAI significantly reduced. Most of the dry weight of the plant by irrigation on 80 mm of Class A pan evaporation rate was obtained, which was significantly different to other treatments and the lowest plant dry weight by 180 mm evaporation from irrigation class A pan evaporation rate was 1080 g/m2, which is also a significant difference with other irrigation treatments. Effect variety on total dry weight of the plant is not significant. In all treatments, dry matter accumulation trend was maintained until maturity after the end of the dry season because of the falling leaves fell. With increasing drought stress reduced dry matter. The highest rates of net assimilation rate among irrigation treatments used for the treatment mm 180 and then to the moderate drought stress 150 mm evaporation from pan class (A) and then severe stress (80) mm evaporation from pan class A). Compare the net assimilation rate showed that NAR sunflower cultivars increased during the first growing season and then downward path and fell. So the Euroflora because more leaf area index and the shadow of the upper leaves on the lower leave NAR was less than the other varieties.
    Conclusions
    Results showed that total dry matter, leaf area index, net assimilation rate and crop growth rate were decreased by drought increasing from 80 to 180mm. The least evaporation (150mm) had the highest amount of mentioned traits. Among cultivars, azargol had higher total dry weight because of having growth period and then higher LAI, total dry weight but it had lower NAR and CGR because of higher LAI and shading of upper leaves, then it is recommended to use Record cultivar.
    Keywords: Crop growth rate, Leaf area index, Net assimilation rate, Total dry matter
  • Zhaleh Zarei, Hasan Heidari * Pages 521-530
    Introduction
    Drought is the most limiting factor for production in arid and semi-arid areas. Iran agricultural sector uses more than 90% of water (Masomi et al., 2015). So drought is an unavoidable problem in Iran. Wick irrigation system is a sub-surface system including an instrument for water conduction by capillary movement from a source to plant roots. Sub-surface systems are more efficient than common irrigation system in terms of time and cost (Son et al, 2006). Research on bean showed that sub-irrigation method reduced water consumption by 55% compared to furrow irrigation (Sepaskhah et al., 1976). Because of rainfall reduction, global warming and remarkable surface water loss by evaporation, this study aim was to determine water consumption amount in wick irrigation compared to common irrigation (surface irrigation) and design and practice wick irrigation system in farm.
    Materials And Methods
    In order to investigate effect of wick irrigation on water use efficiency in sunflower, an experiment was research was carried out as a randomized complete block design with three replications at research farm, college of agricultural science and engineering, Razi Uinversity, Kermanshah, Iran in 2015. Treatments included common irrigation (surface irrigation) as a control and wick irrigation. Plant and stem height, leaf dry weight, stem dry weight and total dry weight were recorded. Leaf area was calculated by Digimizer (P30download, 2016). Turner and Kramer (1980) method was used for computing leaf relative water content. Specific leaf weight (SLW) was calculated using leaf dry weight (LDW) and leaf area (LA) as SLW=LDW/LA. Water use efficiency (WUE) was computed using water consumption (WC) and dry matter (DM) production as WUE= DM/WC (Farre et al., 2006). Data was analyzed using SAS (ver. 9.2) software and means were compared using LSD at probably level of 0.05.
    Results And Discussion
    Wick irrigation had more leaf relative water content than surface irrigation. It was probably due to more and stable access to water in wick irrigation. Wick irrigation had higher plant and stem height than surface irrigation. Our result is in accordance with Bhattarai et al., (2003) findings. Wick irrigation had leaf area as much as surface irrigation; however its water consumption was lower than surface irrigation. Rafeie et al., (2004) reported that drought reduced leaf area. There was no difference between irrigation systems in terms of specific leaf weight. Wick irrigation was more water-efficient than surface irrigation. It was due to that soil capping and soil surface wetting is lower in wick irrigation. Continuous availability to water and no waterlogging condition can also improve plant growth and increase water use efficiency. Wick irrigation produced higher dry matter than surface irrigation. Probably, wick irrigation increased dry matter production through improving soil ventilation, reducing soil capping and weeds.
    Conclusions
    Wick irrigation had higher performance than surface irrigation in terms of many traits. For example water use efficiency and dry matter were increased by 46 and 43%, respectively. So, it seems that wick irrigation is one of the best irrigation systems in arid and semi-arid areas and more research should be conducted to economize and practice this method in farm.
    Keywords: Biomass, Leaf relative water content, Subsurface irrigation, Water productivity
  • Saeed Reza Hosseinzadeh, Hamzeh Amiri *, Ahmad Ismaili Pages 531-545
    IntroductionWater shortage is the main factor that limits growth in dry environments. Tolerant plant is able to absorb water from the soil even in conditions of limited availability so plants achieve maximum efficiency in terms of growth and productivity. Studies have shown that drought stress alone is the reason for 50 percent reduction in chickpea yield. In Iran, this problem is more serious, as chickpea is often traditionally cultivated at the end of the rainy season. The rapid growth stage of this plant coincides with the time in which the level of moisture in the soil decreases significantly. Therefore, the use of bio-fertilizers seems to be effective for drought condition. Vermicompost production is a method of converting organic waste into usable material in which species of earthworm are employed to stabilize organic waste. Vermicompost is produced by the decomposition of organic material using non-thermal interaction between earthworms and microorganisms. Vermicompost is rich in humic compounds and researchers speculate that the hormone-like activities of humic substances play a role in amelioration of water stress. In comparison with other organic fertilizers, vermicompost consists of high levels of nutrients such as N, P, K, Ca and Mg, as well as micronutrients such as Fe, Zn, Cu and Mn.
    Agricultural land in Iran is facing water shortage and chickpea is an economically valuable crop that has a significant role in the human diet. The present study was done with the following aims: (1) to determine the effect of vermicompost in reducing the effects of water stress in chickpea plants; (2) to determine the best mixture of vermicompost fertilizer and soil in the greenhouse.
    Materials and methodsA factorial experiment with a completely randomized design and three replications was conducted. The first treatment prepared four ratios of vermicompost (VC) and soil as follows: control (100% soil); 10% VC 90% soil; 20% VC 80% soil; 30% VC 70% soil. The second treatment was water stress as follows: control (non-stress; 100% of field capacity); moderate water stress (75% of field capacity); severe water stress (25% of field capacity). Chickpea seeds were soaked in water for 24 h and then planted four to a pot. The pots were kept under a photoperiod of 25ºC (12.5 h), and 15ºC (11.5 h), day and night, respectively. The samples were harvested approximately 45 d after planting (podding stage). The shoots and roots were separated and morphological traits of plant height, number of leaves, number of pod, root area, root diameter and dry weight of shoots and roots were measured. Na, Ca and K concentrations of leaves and roots were determined using the method cited in Chapman and Patt (1961).
    Results and DiscussionResult showed that under non-stress, vermicompost fertilizer resulted in a significant increase in all studied traits. Under moderate stress, application of vermicompost significantly increased plant height (19%), number of leave (23%) and pod (32%), root area (23%) and root volume (69%), K (37%), Ca (54% and 30%) concentrations in leaves and roots. Under severe stress, addition vermicompost to soil at 30% level led to significant increase on number of leave (22%) and pod (33%), root diameter (48%), K (45% and 36%), Ca (63% and 33%) concentrations in leaves and roots. Vermicompost containing high levels of nutrients, plant hormones, and with good water storage capacity leads to improved uptake of nutrients that serves to reduce the detrimental effects of drought stress. The increase in plant height, root traits, number of pods and leafs are the result of the stimulation of auxin-like substances, humic and fulvic acids produced during vermicompost consumption. It appears that the use of vermicompost provides better conditions for water and nutrient absorption and allowing plants to spend less energy for root growth.
    ConclusionThe results of this study show that under non-stress and moderate conditions, application of vermicompost can improve chickpea growth. Vermicompost facilitates an increased uptake of mineral nutrients such as K and Ca from the soil under conditions of water stress. According to the results of this study, using of vermicompost and soil mixture recommended to ameliorate the negative effects of water stress.
    Keywords: Drought stress, Growth features, Nutrition, Organic fertilizer
  • Hosein Sartip *, Ali Reza Sirousmehr Pages 547-558
    IntroductionCumin of the apiaceae family is a annual plant with thin and aromatic branches that height is variable between 15 -50 cm that depending on the environmental conditions (Kaffi et al., 2002). Drought stress as a factor in reducing plant growth in many regions of the world is that seriously limit crop production and climate changes in the world, the situation is more serious (Anjum et al., 2011). Salicylic acid as a phenolic hormone, within a plant setting performs and its role in the immune system against abiotic (pathogens) and abiotic (drought, salinity, heavy metals and ozone) is well known (Klessig and Malamy, 1994). It has been reported that application of salicylic acid in the tomatoes has helped to improve the growth in drought stress (Senaratna et al., 2000).
    Materials and methodsThis research during the crop year 2014 was conducted at the research farm of Zabol university Institute. The experiment was done as a split plot in a randomized complete block with three replications. water availability in three level: 50 mm (control), 100 mm and 150 mm evaporation (high stress) from evaporation pan class A as the main factor and different levels of foliar application of salicylic acid ] 0 (no spraying), 1 and 3 mM) were considered as subplots. Measuring photosynthetic pigments by lichtenthaler (1994), proline by Bates et al (1973) and soluble carbohydrate by Keles and Oncel method (2004) were measured. Harvest, in order to calculate yield cumin seed, was done in ripening stages. Statistical analysis was performed using SAS version 1.9 and averages were compared with Duncan's multiple range test at the 5% level.
    Results and discussionThe results of data analysis showed that the interaction of water availability in salicylic acid on proline of leaf was significant at 1 percent probability level. The highest leaf proline (7.78 micromoles per gram) was obtained by 150 mm evaporation of pan and foliar application 3 mM salicylic acid that compared to control treatment (50 mm evaporation of pan and foliar application 0 mM of salicylic acid) increase 96.96 percent indicated. Drought stress caused a significant increase in carbohydrate of cumin leaves at 1 percent probability level. Results showed that the interaction of water availability in salicylic acid on chlorophyll b at 5% and carotenoids leaves was significant at 1% probability level. Results showed that interaction water availability in salicylic acid on grain yield were significant at the 5% level and the highest grain yield (98.9 grams per square meter) in 50 mm evaporation from pan irrigation and foliar application of 1 mM salicylic acid was obtained.
    Reduce the rate of growth under drought stress, the compatibilizer state of to survive the adaptation under stress condition, because plant instead of used nutrients and energy for shoot grow, used for the storage molecule leads against stress (Khalid, 2006). In fennel suitable irrigation leads to better growth, more leaf area, followed by the growth gets better (Buchanan-Wollaston et al., 2003). Salicylic acid by increasing the activity of Rubisco enzyme and chlorophyll increases the photosynthetic rate (Sing and Ushs, 2003). Foliar application of salicylic acid was significant effects on yield and yield components of cumin (Asfini Farahani et al., 2013). The salicylic acid by inducing Protection interactions through the hormone abscisic acid leads to the accumulation, osmolytes especially proline in the plant (Yoshiba et al., 2005). Accumulation of organic compounds such as carbohydrates and amino acids in the cytoplasm plays an important role in the regulation of osmotic pressure plant (Flagella et al., 1995). Increase the amount of carbohydrates and proline under drought stress has been reported in in chamomile (Arazmju et al., 2010). Lowering the activity of photosystem ІІ, reduced RuBisCO enzyme activity and inhibits the synthesis of ATP, causes the formation of free oxygen species in chloroplasts increase. In drought stress, lack of water causes decomposition of chlorophyll and glutamate that is chlorophyll and proline precursor the effect of drought has become as a proline and thus reduced chlorophyll content (Lawlor and Cornic, 2002). A significant increase in chlorophyll and carotenoid in the foliar application of salicylic acid has been reported and The results of this affair have considered increasing the photosynthesis rate (El-Tayeb, 2005).
    ConclusionThe results showed that cumin to when faced with drought stress, the osmotic regulation mechanism used by the accumulation of proline and soluble carbohydrates and in this way to tolerate the water shortage conditions.
    Keywords: Chlorophyll a, Evaporation pan, Grain yield, Photosynthetic pigments, Proline
  • Marzieh Farsi, Farzin Abdollahi *, Amin Salehi, Shiva Ghasemi Pages 559-570
    IntroductionMarjoram is an annual medicinal plant of Labiatae family. This plant is native of south-east of Mediterranean regions and grown in different countries including Iran. Marjoram has great economical and industrial importance and since ancient times was known for its medicinal properties (Baatour et al., 2011). Water deficit is one of the most important factors limiting crop yield (Munns, 2002). Drought stress can cause changes in the morphological, physiological and biochemical characteristics of plants including medicinal plants (Hasani and Omidbaigi, 2002). In drought conditions, chemical compounds, including sugar, protein and chlorophyll content differ between plants and this could be involved plant resistance to drought. Plant nutrition with microelements such as Zn, can improve plant tolerance to drought stress (Alloway, 2004). Some researcher indicated that Zinc contributed in improvement of plant growing conditions especially in drought conditions (Misra, 1992). The present study was conducted in order to evaluate the physiological responses of marjoram to Zn application levels under drought stress conditions.
    Materials and methodsIn order to study the physiological responses of marjoram (Origanum Majorana) to use of zinc under drought stress, a factorial experiment was conducted as a completely randomized design with three replications during 2014-15 in the greenhouse of the University of Hormozgan. Experimental factors were included three drought stress levels (soil moisture equal to 50, 75 and 100% of field capacity) and three concentrations of zinc fertilizer (concentrations of 0, 1 and 3 per thousand as foliar spraying). Drought stress was applied in 8 to 10 leaves stages. Fertilizer solutions sprayed on the 20th day after onset of drought stress for four times (before flowering) at intervals of ten days. Ten days after the third application of zinc solutions, physiological traits such as chlorophyll, soluble sugars, anthocyanin contents and catalase activity were measured. In order to measure dry weight, essential oil content, the marjoram plants were harvested in complete flowering stage. Data analyses were carried out using SAS. Means were compared with LSD (Least significant difference, P=0.05) values.
    Results and discussionDrought stress had significant effect on all traits except the essential oil content. Spraying of Zn fertilizer had significant effects on all evaluated traits with the exception of chlorophyll a content and catalase activity. Interaction of Zn fertilizer with drought stress had significant effects on chlorophyll a, b and total and anthocyanin contents, and essential oil percent. Results of this study showed that when marjoram grown in soil with moisture equal to 75% of field capacity, chlorophyll a, b and total increased significantly, while in 50% of field capacity soil moisture, carotenoid, soluble sugars, anthocyanin content and catalase activity increased significantly. Some researchers indicated that in drought stress conditions synthesis and accumulation of plant pigments and soluble sugars can increase plant tolerance to stressful conditions through adjusting and maintaining osmotic pressure and maintain cell membrane stability (Kleff et al., 1994). Results of mean comparison indicated that Zn spraying at three per thousand concentration increased chlorophyll b and total significantly, while Zn spraying at one per thousand concentration increased soluble sugar and essential oil content significantly. Spraying of Zn solution, improved physiological characteristic of marjoram plants, so that at drought stress condition equal to 75 and 100% field capacity Zn spraying at one per thousand concentration, increased chlorophyll a, b and total and anthocyanin content and essential oil percentage, significantly. Spraying of marjoram plants with low concentration of Zn increased plant tolerance to drought stress and therefore increased plant growth characteristics via increasing in chlorophyll, carotenoid, anthocyanin and soluble sugar. Cakmak (2000) reported that Zn can improve physiological characteristics of plants via cell protection against reactive oxygen species.
    ConclusionBased on these results, the effect of drought stress on all traits except for essential oil content was significant. As well as the effect of different levels of zinc fertilizer on chlorophyll b, carotenoids, soluble sugars and anthocyanin were significant. These results indicated that Zn application at drought stress condition may be through promote plant pigment synthesis improved marjoram growth and therefore essential oil percentage.
    Keywords: Essential oil, Fertilizer spraying, Field capacity, Medicinal plants
  • Hamid Reza Fallahi *, Morteza Ghorbani, Mahsa Aghhavani-Shajari, Alireza Samadzadeh, Mehdi Khayyat, Zahra Maraki, Amir Hossein Asadian Pages 571-582
    IntroductionRoselle or Hibiscus sabdariffa L. is an annual herbaceous plant which grows properly in tropical and sub-tropical areas. Sepals are the main commercial part of roselle with unique brilliant red colour and flavor which are containing many nutritional compounds such as anthocyanin and vitamin C. Accordingly, sepals commonly are used in food industries for production of beverages, juices, jams and syrup (Duangmal et al., 2008; Sanjari-Mijani et al. 2015). Therefore, production of high quality sepals via the good agronomic practices is an important topic in roselle cultivation. So far, the effect of irrigation management (Rahbarian et al. 2011), mycorrhizal inoculation (Sembok et al. 2015) and humic acid application (Sanjari-Mijani et al. 2015) on some qualitative and quantitative indices of roselle has been evaluated in some studies. However, the impacts of mentioned factors on colour characteristics of dried sepals including hunter color values, colour intensity and hue angle has not been studied. Therefore, due to the impact of colour on marketability and drug quality, the aim of this study was to evaluate the effect of water availability, mycorrhizal symbiosis and humic acid application on colour indices of dried sepals in roselle.
    Materials and methodsIn this experiment, the influence of irrigation regimes [irrigation after 100 mm (normal irrigation) and 200 mm (deficit irrigation) pan evaporation], humic acid application (0 and 4 kg.ha-1) and mycorrhizal inoculation (Glomus versiforme, Glomus intraradices and control) were studied on colour characteristic of roselle sepals. For this purpose an experiment at the form of split-split-plot layout based on a randomized complete block design with three replications was carried out during 2015-16 at research field of Sarayan Faculty of Agriculture (33ºN, 58ºE, 1450 masl, annual precipitation of 150 mm and annual temperature of 17ºC.) in east part of Iran. Seed planting was done on 20 April using Sistan & Balochestan ecotype with 10×50 cm intra and inter-rows distances. Humic acid was used in irrigation water two times during vegetative growth of roselle i.e. 15 and 35 days after emergence. All plots were irrigated similarly two times during the first week after seed sowing and then irrigation treatments were exerted separately in each plot until November 15 when irrigation was stopped. After that, calyces belonged to each treatment were harvested and dried separately in ambient temperature and shade condition of laboratory and then were used for colour analysis. Color of dried sepals was evaluated using a colorimeter (TES 135, Shenzhen Youfu Tools Co., Ltd. - TAIWAN). Results were expressed as Hunter color values (l*, a* and b*). L is the brightness ranging from 0 (black) to 100 (white). The value a* is the redness ranging from negative values for green to positive values for red. The value b* is the yellowness ranging from negative values for blue and positive values for yellow. In addition, color intensity (Chroma), hue angle and browning index were calculated using equations presented by Duangmal et al., (2008). Finally, data were statistically analyzed using SAS 9.1 and means were compared by duncan test at 5% level of probability
    Results and discussionResults showed that the effect of experimental factors was significant on most of colour indices in roselle calyces. Droughts stress reduced a* value, hue angle and chroma by 22, 53 and 15% respectively. Humic acid application also reduced the amount of hue by 63% while increased the b/a by 25%. Both mycorrhizal species enhanced the hue index by 66% compared with control treatment. Results of interaction effects revealed that the highest amount of b/a (0.19) was obtained at droughts stress × humic application × mycorrhizal inoculation, while its lowest value (0.02) observed at no stress ×no-humic ×no-inoculation treatment. In addition, the maximum amount of hue (215 º) was obtained at no water stress × humic application × mycorrhizal inoculation using Glomus versiforme. The treatment of no stress × no humic × mycorrhizal symbiosis produced the maximum amount of redness index. Moreover, a significant correlation was observed between a* with chroma (.64**) and browning index (-0.71**) as well as between hue and redness index (.00**). Overall, colour quality of roselle sepals was more suitable under appropriate water supply. In addition, mycorrhizal inoculation partially reduced the negative impacts of droughts stress on calyxes colour characteristics. The reducing effect of sever water stress and the positive role of mycorrhizal inoculation on growth, yield and quality of roselle has been previously reported by other researchers (Rahbarian et al., 2011; Sembok et al. 2015). It has been reported that red anthocyanins in sepals of roselle are responsible of its brilliant red colour (Duangmal et al., 2008). Our qualitative analysis revealed that the amount of anthocyanins in drought stress condition was 12% lower than no stress treatment. Furthermore, mycorrhizal symbiosis using G. intraradices and Glomus versiforme improved the amount of this index by 20 and 5%, respectively (data are not presented). These observations are in accordance with the trend of redness change in dried sepals. Accordingly, it seems that more redness and a*, hue angle in no stress and inoculation treatments is because of more anthocyanin content in related plants. This finding is also understandable from positive regression relation between redness index and sepals anthocyanin content.
    ConclusionsConsidering to colour characteristics and regards to yield and qualitative indices such as anthocyanin and vitamin c content (data are not presented), it seems that appropriate water availability and use of mycorrhizal symbiosis are two good strategies for roselle production.
    Keywords: Brightness, Chroma, Deficit irrigation, Hue angle, Medicinal plants
  • Yaeghob Arefi, Elnaz Farajzadeh Memari Tabrizi * Pages 583-593
    IntroductionWater stress is the most important non-disease stress with adverse effects on plant growth and yield. The inadequate emergence of seedlings and inappropriate establishment of the factors limiting the growth and yield of plants, especially in areas with low rainfall. Successful deployment of seedlings increases the competitiveness of crops against weeds and increases plant resistance to dehydration and pests. On the other hand, by expediting the treatment, provided enough time to plant a second plant. Studies have shown that priming improves germination, reduces the time of emergence of seedlings, and results in improved plant deployment. Selection of suitable cultivar and seed priming modify the adverse effects of moisture stress on plant growth and development. The aim of this study was to investigate the effect of different levels of irrigation and duration of priming on growth and yield and corn cultivars.
    Materials and methodsThis research was carried out in 1394 in laboratory and field conditions. In laboratory conditions, factorial experiment was conducted based on a completely randomized design. The first factor consisted of three levels of polyethylene glycol application (irrigation with distilled water, irrigation with polyethylene glycol solution (distilled water, concentration of 12% by volume and irrigation with polyethylene glycol solution with concentration of 25% by weight), the second factor of priming time (zero, 8, 12 and 24 hours), the third factor consisted of two cultivars of maize (704 and 604). In this study, the effect of simultaneous priming (zero (no priming), 8, 16 and 24 hours) in the field conditions, and two varieties Corn (706 and 604) under three moisture conditions (irrigation after 70, 110 and 150 mm evaporation from class A evaporation pan) was investigated. The experiment was carried out in three replicates and split factorial based on randomized complete block design. The application of irrigation levels after plant deployment of corn in the 6-8 leaf stage in the field began. Priming seeds were done before planting.
    FindingsIn laboratory conditions, in 704, 25% m/v of polyethylene glycol treatments decreased germination percentage by 3.8%. The highest seedling dry weight was obtained in two treatments of distilled water, 16 hours priming and 604, and 12% by weight of polyethylene glycol, 8 hours priming and 704 with a value of 1.06. In this study, in distilled water, priming had no significant effect on dry weight of seedlings of corn, but in 25% of treatment weight of polyethylene glycol, priming treatments of 16 and 24 hours reduced to 86 and 80% in 704 and priming treatments 8, 16 and 24 Hours at 604 significantly increased 52, 52 and 72% in seedling dry weight. In this study, the highest germination rate coefficient was obtained in distilled water and 8 hours priming with 0.85 per day, and the lowest in treatment of 25% by weight of polyethylene glycol day and non-priming with 0.4%. The treatment of 25% polyethylene glycol in non-priming and 8 hours priming treatments caused a significant decrease of 0.36 and 0.20 per day in germination rate, but did not affect germination rate in priming treatments of 16 and 24 hours. There was no significant difference in grain yield between cultivars in terms of field conditions. Moisture stress had a significant effect on yield loss, so that in case of non-priming, irrigation after 150 mm of evaporation caused a decrease of evaporation of 52% in grain yield compared with irrigation after 70 mm evaporation. However, priming of corn seeds over a period of more than 16 hours prevented this decrease in water-induced function. In the absence of priming, priming for 8 and 16 hours, irrigation treatment after 110 mm evaporation from the pan had no effect on grain yield. Dehydrated weight, ear weight, and shoot dry weight, leaf chlorophyll content, leaf area and plant height decreased 20.7, 21.9, 14.9, 42.9 and 10.6%, respectively. Priming had a significant positive effect on traits and 8 hours priming increased 19.9%, 15.3% and 19.2%, leaf area, shoot weight and seed number, but depending on the treatment time, the effect of priming was different.
    Conclusionconsidering the results of the effect of priming against water deficit, there was no significant effect on seed yield under full irrigation conditions. There were no differences between the cultivars in most of the traits. In general, it seems that in the studied traits under full irrigation conditions, the lower periods of pre-treatment had a more positive effect, while in dehydration conditions, the effect of longer priming periods was better. The total priming of 8 and 16 hours was the most effective period of priming for grain yield.
    Keywords: Cultivar, Maize, Priming, Water shortage
  • Mohammad Reza Ramezani, Mohammad Javad Seghatoleslami *, Mohammad Hasan Sayyari Zohan, Seyyed Gholamreza Moosavi Pages 595-604
    IntroductionToday salinity stress and salinization of soil is one of the most important environmental stress. As the amount of salt increases the plant growth rate decreases. Salinity cause imbalance in soil nutrient content. At this condition we have to use suitable nutrients to achieve appropriate yield. This experiment was conducted to evaluate the effect of salinity and zinc and iron application on yield and some morphological traits and quality of ajowan.
    Material and methodsA split plots based on randomized complete block design with three replications was used in Khezri, South Khorasan in 2010. Salinity levels of irrigation water (970, 3500 and 7700 µs.cm-1) andfoliar application of micronutrients (control, Fe, Zn and Fe Zn) were as main plot and sub plot, respectively. Each plot consisted six rows. The length of rows was 4 m. Distance between rows and plants on the rows was 40 and 20 cm, respectively. Data analysis was conducted by MSTATC and SPSS software and means were compared by Duncan’s multiple range tests at 5 % probability level.
    Result and DiscussionSeed yield significantly affected by salt stress and its interaction with foliar application treatment. The highest (258.11 g.m-2) and the lowest (171.56 g.m-2) seed yield respectively was related to treatments low salinity iron and high salinity (iron츩). In high salinity conditions, which showed a significant reduction in seed yield than low and common salinity, there was no significant difference between the levels of foliar application with control. In fact, iron foliar application in low salinity (control) significantly increased seed yield, but iron zinc spray application did not significantly change seed yield in comparison with control (without foliar application). On the other hand, in common salinity stress, foliar application treatments did not increase the yield, but in high salinity, the treatments increased seed yield.
    In low salt stress conditions foliar application of iron increased significantly seed yield, however foliar application of iron츩 could not affect seed yield. On the other hand, in the common salt stress conditions, foliar application treatments could not increase seed yield, but under severe salt stress these treatments enhanced the yield. In general, under low, common and high salinity stress, the highest seed yield respectively was related to foliar application treatments iron, control and zinc. Seed yield reduction under salinity stress is related to its impact on shoot growth. In this experiment seed yield reduction was related to the decline of umbel number per plant. Correlation coefficient between seed yield and umbel number per plant also was positively significant. Like seed yield, salinity stress reduced different growth parameters such as plant height and branch number per plant. Effect of foliar application on seed essential oil percent and yield was not significant. However, in sever salinity stress, like seed yield, essential oil yield also declined. Although in high and common salt stress, foliar application had not any significant effect on essential oil yield, but under low salt stress, iron foliar application significantly increased essential oil yield. The results of this experiment show that the response of plant height and branch number per plant to irrigation treatments are opposite to each other. Considering that in all foliar application treatments, plant height increased, it can be concluded that the stimulus effect of these treatments on stem longitudinal growth causes the competition of the main stem with lateral branches. Therefore the number of branch per plant in iron and zinc foliar application treatments has declined. It has been reported that zinc deficiency can reduce plant height and yield due to adverse effects on biosynthesis of auxin.
    ConclusionTotally, the results of this experiment showed that, due to the significant interaction between salinity and foliar application, microelements should be used with care and after further studies in this plant. Possibly, some plant responses to foliar application and salinity interactions can be related to the presence of different compounds in water used in salinity treatments. Also, the lack of response of some growth parameters such as yield and plant height to the foliar application can be due to complicated plant nutrition relationships with soil conditions such as pH and other soil nutrient concentrations.
    Keywords: Branching, Essential oil, Height, Micronutrient, Umbel
  • Fardin Ghanbari, Fakhrodin Salehi, Mohammad Sayyari * Pages 605-614
    IntroductionExposure of tropical and subtropical plants, such as tomato, to low temperatures may stunt the plant’s growth, induce wilting and necrotic lesions on leaves, and increase susceptibility to diseases and pathogens (Hällgreen and Öquest, 1990). The symptoms of stress-induced injuries in these plants appear from 48 to 72 h, however, this duration varies from species to species and also depends upon the plant sensitivity to chilling stress. Various phenotypic symptoms in response to chilling stress include reduced leaf expansion, wilting as well as chlorosis (yellowing of leaves) and may lead to necrosis (death of tissue). Chilling also severely hampers the reproductive development of some plants (Mahajan and Tuteja, 2005).
    A strategy, which has recently been investigated in plants under stress condition, is cross-resistance, i.e., exposure of tissue to stress conditions often induces resistance to other stresses. For example, salt stress stimulates cold hardiness in potato and spinach seedlings
    (Ryu et al., 1995). Various mechanisms explaining the phenomenon of cross-resistance
    have been proposed and often, although not always, it has been suggested that specific proteins are induced by one type of stress and these are involved in the protection against other types of stress.
    Artificial Neural Networks (ANN) are as an analytical alternative to conventional modeling techniques, which are frequently limited by strict assumptions of normality, linearity, homogeneity, and variable independence (Salehi, 2014). Neural network model was used for potato storage process modeling (Abdulquadri Oluwo et al., 2013), detecting chilling injury in red delicious apple (ElMasry et al., 2009), to detect defects (leaf roller, bitter pit, russet, puncture and bruises) in Empire and Golden Delicious apples(Kavdır and Guyer, 2004) and Lettuce (Lactuca sativa L.) yield prediction under water stress (Kizil et al., 2012) . In this study, artificial neural network modeling was used to predicting chilling resistance of tomato seedlings following imposing drought stress pretreatment with application 0, 10 and 20% poly ethylene glycol (PEG).
    Materials and MethodsTomato seeds, cultivar Falaat CH, which is one of the most important cultivars grown in Hamedan, were disinfected in 1% (active ingredient) sodium hypochlorite solution for 10 min to eliminate possible seed-borne microorganisms, then they were rinsed for 1 min under running water prior to drying for 30 min at room temperature. After that, Seeds were planted into plastic pots filled with a 2:1 mixture of coco peat: perlite. The pots were then transferred to the greenhouse with average temperature of 25.5/19.5°C (day/night) and natural light. When the seedlings developed four true leaves, they were pretreated with 10 or 20% PEG for 7 days or not. After drought, the seedlings were subjected to chilling 6 h/day at 3°C for 6 days. All plants were assessed 72 h after the end of chilling stress to determine the extent of chilling injury and data were collected.
    In present study, data were collected from experiments and then all data were randomly divided into 3 partitions: training (40%), validating (20%), and testing data (40%). The testing data was used for estimating the performance of the trained network on new data. The Neurosolution software 6.01 (USA) was used for designing the ANN model.
    In order to predicting chilling effects on tomato seedling attributes, multi-layer perception neural network with 2 input (drought stress and chilling stress effects) and 8 outputs (chlorophyll a, chlorophyll b, total phenol, relative water content, root electrolyte lekage, F0, Fm and proline) was used.
    Results and DiscussionThe results showed that the ANN with 7 hidden neurons had the minimum mean absolute error values and high correlation coefficients. The overall agreement between ANN predictions and experimental data was also significant (r=0.92). A plot of the MSE and the number of epochs is shown in Fig. 2. A sharp drop was observed for MSE in the first little iteration (fast training) and training was completed after about 9 epochs. This is a well-known characteristic of the LM optimization method (Salehi and Razavi, 2012).
    Feed-forward back-propagation ANN models were developed by ElMasry et al. (2009) to investigate the ability of hyperspectral imaging and ANN techniques for the detection of chilling injury in Red apples. They reported that classification accuracy of above 90% was obtained with the use of selected five optimal wavelengths. In another study neural network models was used to predict shelf life of greenhouse lettuce by Lin and Block (2009). Using 2-stage neural network models, an R2 of 0.61 could be achieved for predicting remaining shelf life. This study indicated that neural network modeling has potential for predicting chilling tolerance of tomato seedlings following imposing drought stress pretreatment.
    Keywords: Chlorophyll, Florescence, Proline, Total phenol
  • Mohsen Tarighaleslami, Mohammad Kafi *, Ahmad Nezami, Reza Zargham Pages 615-625
    IntroductionPlants are affected by many unfavorable environmental factors and therefore crop growth and development is retarded. Cold and water stress impose a considerable damage to the economy and country’s agricultural production every year. Salicylic acid is of phenolic compounds which is found in many plants, and considered as quasi hormonal substance that plays an important role in the growth and development of plants. Salicylic acid plays an important role in resistance to environmental stresses. The aim of this study was to investigate the effects salicylic acid spraying on alleviating the chilling and drought stresses on yield and agronomic traits of maize single cross 400.
    Materials and methodsThis experiment was performed as a split-split plot in a randomized complete block design with three replications during 1394 in the greenhouse and the Research Farm of Faculty of Agricultural Ferdowsi University of Mashhad. The main plot of cold stress at two levels (non-stress and cold stress at 5ºC for 12 hours at 4th leaf stage), sub factors were three levels of irrigation (100, 75 and 50% of water requirement) and sub-sub plot was spraying with salicylic acid (non- (control) , 200 and 400 µM spraying
    After cold stress, seedlings of Single cross 400 were planted in the field. The plots were prapared with four meters length and three meters widths and row spacing of 75 cm with 75000 plants per hectare. At the end of the growing season to determine yield components, five plants were randomly taken from each plot from one square meter and biomass and kernel yield was recorded. MSTATC software implemented for statistical analysis and the means were compared using LSD test.
    Results and discussionThe effect of drought stress and salicylic acid on the seed number per plant was significant. So that 100% irrigation %cause to improve 34.2% %in seed number per plant compared to 50% %of water requirement. Spraying plants with 200 and 400 µM improved the trait at a rate of 13.6 % compared to non-spraying (control). Effects of drought stress, salicylic acid and interaction of salicylic acid with drought on seed yield were significant. The treatment of 100% water requirement with 400 µM spraying with an increase of 54.3% showed the highest seed yield compared to 50% water requirements with spraying. In another study also corn foliar spaying with salicylic acid in flowering stage increased seed yield (Bayat et al., 2010). Effects of drought stress and salicylic acid and their interaction on biological yield were significant. The highest biological yield was obtained in 100% water treatment with 400 µM salicylic acid spraying with 55.2% higher biomass compared to 50% water treatment with similar salicylic acid spraying.
    Harvest Index in treatment of 400 µM salicylic acid spraying in irrigation conditions of 100% water requirement was 11.1% more than in irrigation conditions of 50% water requirement with the same salicylic acid spraying. Setter et al (Setter et al., 2001) similarly reported that corn grain yield reduced under drought stress.
    ConclusionsThe results of this study showed that cold stress did not have negative impact on SC400 corn hybrid on tested traits. But the drought stress reduced corn yield components (such as the number of seeds and rows in corn), seed weight, biological yield, seed yield, and harvest index. 400 µM salicylic acid applications can be significantly increased biological yield and seed yield SC400 corn.
    Keywords: Biological yield, Harvest index, Water requirement, Water productivity, Water use efficiency
  • Ahmad Nezami *, Ebrahim Izadi-Darbandi, Maryam Janalizadeh Ghazvini, Rouhollah Hassanbeigy Pages 627-639
    IntroductionFlixweed is an annual dicotyledonous winter herb from Cruciferae (Brassicaceae) family which grows in many countries of the world. In Iran it is seen in many of wheat and canola producing regions. Flixweed is used for healing a variety of diseases such as measles and smallpox, cough, asthma, edema and tumor. It also has diuretic, anticancer, antipyretic, antioxidant, anthelmintic, analgesic and tonic activities [2]. In temperate and cold regions of Iran, winter cold is one of the most important environmental stresses which affect growth, development and yield of plants. So determination and improvement of freeze tolerance of winter plants such as Flixweed might promote their cultivation and utilization in cold regions. At present measuring the survival after a recovery period which is followed by a freezing test in controlled conditions is a common method for determining the level of plants freeze tolerance. Calculation of LT50 point or critical temperature based on survival percentage of plant is considered as a quantitative and simple method for evaluating the cold tolerance [1]. But sometimes this criterion is not enough alone and other indices (for example dry weight and Reduced dry matter temperature 50% of plants (RDMT50)) are used to achieve a more accurate estimation of cold tolerance level [3]. In spite of numerous medicinal and industrial properties of Flixweed, there is not a lot of information about freeze tolerance of this plant, so the objective of this study was evaluating the freeze tolerance of Flixweed by survival % and some of growth traits after recovery period.
    Materials and methodsIn order to evaluate freeze tolerance in some of Flixweed, a factorial experiment was conducted based on completely randomized design with three replications in faculty of agriculture, Ferdowsi University of Mashhad in autumn of 2009. Experimental factors include five ecotypes of Flixweed (Eghlid, Sabzewar, Hamedan, Torbat-e-Jam and Neyshabour) and 10 freezing temperature levels (from zero to -18 with 2 °C intervals). For this aim, Flixweed seeds were cultivated in pot in autumn and they were grown in natural weather until 5-7 leaf stage. Afterward for applying freezing temperatures, plants were transferred to a thermo gradient freezer. The initial temperature of programmable freezer was 5°C; but gradually decreased in a rate of 2°C.h-1 until reached to desired temperatures. When the freezer temperature reached to -2°C, the plants were treated by the Ice Nucleation Active Bacteria (INAB) to help the formation of ice nuclei in them, also to prevent from super-cooling of samples and to ensure that the mechanism of freeze resistance is tolerance not avoidance. After artificial freezing stress applying (which lasted up to two hours for each freezing temperature); Flixweed seedlings were transferred to greenhouse for recovery. Three weeks after freezing stress, survival percentage (SU %), Lethal temperature for 50% of plants according to the survival% (LT50su), number of leaf and reduced number of leaf temperature 50% (RNLT50), number of node and reduced number of node temperature 50% (RNNT50), dry weight and reduced dry matter temperature 50% (RDMT50) were evaluated. Analysis of variance was performed by MSTAT-C software and correlations between data were carried out by MINITAB 16 program. Mean separation was conducted by least significant difference (LSD) test at 1% probability level.
    Results and DiscussionResults showed that Hamedan ecotype had the highest SU% and Neyshabour ecotype had the lowest SU%. In Eghlid and Neyshabour ecotypes, decline of SU% begun from higher temperarures (-8 °C) compared with other ecotypes (-10 °C). This trend was seen for dry weight and number of leaf too. At -12 °C, number of node in Hamedan ecotype decreased 30% approximately than control, while in Eghlid and Neyshabour ecotypes, this reduction was much higher. In this experiment LT50su ranged between -10.2 to -12.1 °C depending on the ecotypes. Ranking of Flixweed ecotypes according to the LT50su, RNLT50, RNNT50 and RDMT50 indices showed that the Neyshabour and Hamedan ecotypes were the most sensitive and tolerant Flixweed ecotypes to freezing stress respectively. In this survey, there was high and positive correlation between survival percentage and dry weight (r=0.69***), in addition there was negative and significant relationship between SU%, LT50su and RNNT50 (r=-0.67*** and r=-0.82*** respectively).
    ConclusionAccording to these results, it seems that temperature threshold for winter injury happening in Flixweed is -12 °C. Despite this for better understanding of cold tolerance of Flixweed, further researches are required under controlled and field conditions.
    Keywords: Dry weight, Ecotype, Freezing, LT50, Survival percentage
  • Mahmood Attarzadeh *, Hamidreza Balouchi, Majid Rajaie, Farzaneh Pooladi Pages 641-653
    IntroductionAbscisic acid (ABA) is a phytohormone which has a main role in plant life cycle and regulates many physiological processes including plant development and adoptability to environmental stresses. ABA controls water status of plants under stress and noticeably decreases undesirable heat stress damages. Since high temperature stress is a limiting factor for many crops growth and according to literature review there are evidences that ABA can induce thermo tolerance in plants, the present study was designed to evaluate the response of corn to heat stress when seeds are pretreated by ABA.
    Materials and methodsThe experiment was factorial in a completely randomized block design with three replications and was done in agricultural college of Vali-e-Asr University of Rafsanjan in 2013. First factor was seed pretreatment by ABA solutions (zero, 50, 100 and 200 µM L-1) and second factor was different durations (zero, 8, 16 and 24 h) of heat stress in 40º C exerted on hybrid S.C.704 corn seedlings. In darkness seeds were soaked in ABA solutions for 24 h at the temperature of 25 ± 1º C. Following pretreatments seeds were sterilized by distilled water and finally were planted in pots in the depth of 1.5 cm. Seedlings were transported to growth chamber with the temperature of 40º C in four foliate stage to be treated by different heat durations. After thermo treatments seedling were transported to green house and plant responses were measured two weeks later.
    Results and discussionResults indicated that the highest dry weight of shoots was obtained in ABA concentration of 50 µM L-1 but there were no significant differences at probability level of one percent among other concentrations. In addition corn seedlings were able to tolerate 8 h heat duration but negative effects of heat stress was significantly increased in 16 and 24 durations which led to the reduction of shoot dry matter production. Increase in heat duration and ABA concentration caused a significant raise in shoot to root weight ratio so that the highest ratio (31.66 percent) was observed in control treatment and the lowest (3.83 percent) in heat duration of 24 h accompanied with 200 µM L-1 ABA. Leaf relative water content in ABA concentrations of 50 and 100 µM L-1 showed a significant increase at probability level of five percent in respect to control and ABA concentration of 200 µM L-1 which can probably be due to stomata resistance in these treatments and may be used as suitable approach to increase plant thermo tolerance. Negative effect of ABA concentration of 200 µM L-1 on leaf relative water content indicated that ABA concentration must be chosen precisely. Increase in heat duration caused a significant raise in leaf temperature. In heat durations of 16 and 24 h the highest leaf chlorophyll index (27.2 and 24.5 respectively) was obtained in 50 µM L-1 ABA and the lowest ones (21.9 and 18.7 respectively) in 200 µM L-1. Increase in ABA concentration and heat stress led to a significant reduction of chlorophyll a content in corn leaf so that in heat duration of 24 h and ABA concentration of 200 µM L-1 a reduction of 36.9 percent was observed compared to control. In addition a reduction of 17 percent in carotenoids was associated with 24 h heat stress in respect to control. In all three durations of heat stress, rise in ABA concentration up to 100 µM L-1 made a decline in ion leakage while in the highest concentration (200 µM L-1) an increment in ion leakage was observed.
    ConclusionsIn conclusion the results of the present study showed that high levels of heat stress in combination with undesirable concentrations of ABA can create negative effect on plant ability to preserve leaf relative water content and can lead to the destruction of chlorophyll and carotenoids structure and increase the ion leakage. On the other side ABA concentration of 50 and 100 µM L-1 decreased ion leakage while increased the leaf relative water content and chlorophyll index. By these simultaneous effects the corn shoot dry weight was improved under heat stress condition. It seems that external use of ABA can have positive and negative effects on plant growth depending on its concentration. Concentrations higher than threshold tolerance to ABA can cause disturbance in plant physiological processes and restrict plant growth and development.
    Keywords: Leaf Temperature, Dry Matter Accumulation, Maize, Relative Water Content
  • Abdolhossein Rezai, Hamidreza Balouchi *, Mohsen Movahhedi Dehnavi, Ebrahim Adhami Pages 655-671
    IntroductionIn recent years, soil pollution with heavy metals such as cadmium had a progressive trend and causes serious problem in production of crops in polluted zones. Heavy metals released from stationary and mobile origins can be transported in water, air and soil and can be even absorbed by plants, animals and human bodies. Trace elements are currently of great environmental concern. Nowadays, one of the most important environmental problems is pollution of agricultural soils occurs by heavy metals due to human activities. Nowadays, soil pollution with heavy metals as a result of human activities is considered one of the most important environmental stresses in plants, which can lead to the production of reactive oxygen species such as hydrogen peroxide cause. Priming application of gibberellic acid, salicylic acid and potassium nitrate as a suitable option is considered to reduce the toxic effects of cadmium.This study was designed to investigate the effects of priming on physiological traits and sorghum seed germination under cadmium chloride and nitrate stress was conducted in the greenhouse of Yasouj University in 2015.
    Materials and Methodsexperiment was conducted as a factorial based on CRD design with three replications. Treatments first factor were including 800 mg/l gibberellic acid, 0.3 mM salicylic acid, 1% potassium nitrate and control (non-prime). The second factor was included cadmium chloride and nitrate each in four levels (0, 7.5, 15 and 30 mg per kg of soil). Then cadmium chloride and nitrate was added by spraying into soil. Then planting pots were filled with seven kilograms of soil, and after one month (because of the homogeneity of the heavy metal), 4 seeds primed for planting in pots were planted with different levels of cadmium chloride and nitrate. The chlorophyll index, chlorophyll fluorescence, leaf soluble protein and antioxidant enzyme activities were measured. Also, post-harvest seed quality traits including percentage and germination rate, uniformity and vigor and seed weight and seedling length and weight were measured.
    Results and DiscussionThe results showed that the interaction of cadmium and priming for soluble protein, Catalase enzyme, Superoxide dismutase enzyme and seedlling height was significant. The effect of cadmium showed that cadmium chloride 30 mg per kg of soil seed weight decreased to 24% compared to control. Generally all levels of cadmium compared to the control (no cadmium) had a depressing effect on seed weight. Priming planted seeds with 0.3 mM of salicylic acid leads to increase the germination rate and length vigor index of seeds of sorghum under cadmium stress. Also the most weight vigor index was observed in 15 mg per kg of soil cadmium chloride and nitrate and the lowest was belonged to 7.5 and 30 mg per kg of soil cadmium chloride treatments. In relation to the slow germination under stress cadmium cell membrane probably one of the important points is that it is severely damaged cell to leak out and vigor will be reduced. Priming with the reconstruction of damaged cells and reduce barriers to the growth of the fetus and increase the quality and quantity of protein synthesis, increases the development and tolerance to environmental stresses. Speed up seed germination can as a result of increasing enzymes such as Alpha-amylase, increased levels of bio-energy charged in the form of increasing the amount of ATP, increase the synthesis of DNA and RNA, increasing the number and improving mitochondrial function is at the same time.
    ConclusionsIn general, seed priming with 800 milligrams per liter of gibberellic acid, and 0.3 mM of salicylic acid, improved the biochemical and physiological indices of main plant such as increased soluble protein and chlorophyll content, cause to sorghum seedlings resistance to cadmium toxicity and improved the seedling growth and seed weight. As a result, seeds produced in these conditions, have more germination rate and vigor index than the control (non-use of priming).
    Keywords: Anti oxidant enzyme, Germination, Gibberellic acid, Salicylic acid, Heavy metals