وجود گونه Bipolaris hawaiiensis همراه بذور گیاه برنج در ایران

نوع مقاله: گزارش کوتاه

نویسندگان

نویسنده

چکیده

در اواخر فصل زراعی سال 1388، روی نمونه‌های بذور آلوده رقم عنبربو قرمز برنج جمع‌آوری شده از مزارع موسسه تحقیقات کشاورزی واقع در شاوور از توابع شهرستان اهواز، لکه‌هایی به رنگ قهوه‌ای مشاهده گردیدند. پس از انتقال نمونه‌های آلوده به آزمایشگاه، قطعاتی از حد فاصل بخش‌های آلوده و سالم بذور انتخاب شدند و به مدت 20 دقیقه زیر جریان آب شیر شستشو شدند. پس از ضدعفونی سطحی بذور به مدت یک دقیقه در محلول هیپوکلریت سدیم رقیق شده (محتوی 1% کلر در محلول تجاری) و سه بار شستشو با آب مقطر سترون و سپس خشک کردن با کاغذ صافی سترون، قطعات روی بستری متشکل از کاغذ صافی مرطوب (Blotter method)درون تشتک‌های پتری سترون قرار داده شدند. تشتک‌های پتری درون انکوباتور با دمای 25-22 درجه سلسیوس قرار گرفتند. پس از گذشت 17 روز، پرگنه‌های رشد کرده قارچ در اطراف هر قطعه به روش تک اسپور خالص‌سازی شدند. قطر پرگنه قارچ پس از چهار شبانه روز رشد در شرایط تاریکی و دمای 25 درجه سلسیوس روی محیط غذایی سیب‌زمینی دکستروز آگار (PDA)، به حدود چهار سانتی‌متر رسید. رنگ پرگنه قارچ در مرکز تشتک پتری به رنگ خاکستری و در حاشیه به رنگ قهوه‌ای تیره بود.

عنوان مقاله [English]

OCCURENCE OF BIPOLARIS HAWAIIENSIS ASSOCIATED WITh RICE GRAIN IN IRAN

نویسندگان [English]

  • S. NAZARI
  • M. JAVAN-NIKKHAH
  • KH. FOTOUHIFAR
  • V. KHOSRAVI
چکیده [English]

Rice plant is one of the most important and strategic agricultural product with having highest cultivation area after wheat in the world. Several factors including plant pathogenic fungi are causing agents of quantitative and qualitative losses in this plant. Brown spot is an important seed borne disease of rice that caused by different species of Bipolaris. Brown spots observed on infected grains in Shavor of  Ahvaz at the end of crop season in 2009. Infected samples were transferred to laboratory and were cut parts between infected and healthy tissue. These parts were washed under water flow for 20 minutes. Seeds before putting into Petri dishes containing wet filter paper, were disinfected with sodium hypochloride 20% (1% active chlorine) for about 1 minutes and more was washed with  sterile distilled water thrice and dried with sterile filter paper. Petri dishess were incubated under temperature of 22-25˚C. After 17 days, fungal clony formed around cultivated seed part was purified through single spore method. Colony diameter under darkness and optimum temperature was reached about 4 cm on PDA medium. Center and margin of colony was gray and dark brown, respectively. For sporulation, subcultures of colony were transfered on TWA+Wheat straw medium under optimum temperature and alternative light (12 hours darkness and 12 hours lighting). After ten days, conidia were formed on medium and wheat straw abundantly. Conidia were light to dark brown, smooth, often cylindrical, with 3-6 and often 5 pseudoseptum. Length and width of conidia were 8.75-37µm and 5-10µm, respectively.
Conidiophores were single, cylindrical, light to dark brown with maximum height 120 µm and width 2-7 µm. According to the morphological characteristics and based on Ellis (1976) and Sivanesan (1987), the isolate identified as B. hawaiiensis that did not isolated from rice in Iran, before. Thus this is first report of the fungus associated to rice. Pathogenicity test of this fungus was done  in greenhouse. Spore  a suspension of inoculums 5×104 conidia/ml was prepared. No symptom was showed on the leaves and thaus pathogenicity of this strain did not  proved   in greenhouse.