چكيده فارسي :
پوسيدگي طوقه و ريشه در غلات از مهمترين بيماريهاي قارچي بوده و سالانه در بيشتر مزارع ديده ميشوند. از مهمترين عوامل اين بيماري، گونه هاي مختلف Fusarium هستند كه در محصولات زراعي از جمله ذرت خسارت فراواني وارد مي كنند. در بررسيهاي انجام شده در مزارع غلات استانهاي لرستان و ايلام در سال 1395، گياهان داراي علايم مشكوك به پوسيدگي طوقه و ريشه فوزاريومي جمع آوري و به آزمايشگاه منتقل شدند. بررسي هاي آزمايشگاهي نمونه ها بلافاصله آغاز گرديد. جدايه هاي به دست آمده در محيط كشت اختصاصي نش و اسنايدر و DCPA پس از خالص سازي و انتقال به محيط كشتهاي PDA، CLA، KCl، SNA و آب مقطر استريل از نظر ويژگيهاي ميكروسكوپي مورد بررسي قرار گرفتند. مشخصات ماكروكنيدي، ميكروكنيدي، ياخته هاي كنيديومزا، كلاميدوسپور و مشخصات كلني با كليدهاي معتبر موجود (Marasas, 1986; Leslie & Summerell, 2006) تطبيق داده شدند. نتايج نشان داد گونه جداشده با Fusarium polyphialidicum Marasas كاملاً مطابقت دارد. سرعت رشد متوسط، توليد ريسه‌هاي هوايي به رنگ سفيد تا نارنجي كمرنگ، و رنگ سفيد مايل به زرد در پشت پتري روي محيط كشت PDA مشاهده شد. ماكروكنيديوم در اسپوردوكيومهاي سفيدرنگ تشكيل شد
چكيده لاتين :
Root and crown rot is one of the most important fungal plant diseases which is observed in fields annually. One of these agents are Fusarium species which cause lots of damages to crops such as maize. In a survey in cereal fields in Lorestan and Ilam provinces in 2016, plants with fusarium root and crown rot symptoms were collected and were transferred to laboratory. In vitro experiments were started quickly. After isolation in Nash & Snyder and DCPA, isolates were purified and then were transferred to PDA, CLA, KCl, SNA and strile distilled water to microscopic observations. Macrocinidia, microconidia, conidiogenous cells, chlamydospores and colony features were studied according to diagnistic keys (Marasas, 1986; Leslie and Summerell, 2006). Results showed that isolated species were F. polyphialidicum Marasas. Average growth rate, white to pale orange aerial mycelium, white to yellow color in reverse colony on PDA were observed. Robust and large macroconidia with moderately curvature were produced in white sporodochium. Size of these spores were 4.5-6 × 35-65 µm, they were 5-7 septate, with foot shaped basal cell and tapering apical cell. Microconidia were clavate and 0-septate, and 2.5-3.5 × 35-65 µm. Monophialids and polyphialides and single, in pairs, clumps and in chains chlamydospores were another features of this species. According to above properties and identification, pathogenicity test were examined in greenhouse conditions according to Burgess et al. (1994) method. This is the first report of F. polyphialidicum on maize in Iran.
