شناسايي نماتدهاي انگل گياهي خاك‌هاي پوشش گياهي منطقه‌ كهق، شمال شهرستان مراغه در استان آذربايجان شرقي

Identification of plant parasitic nematodes in rhizosphere soils of Kahaq area, north of Maragheh, East Azarbaijan province (Iran)

به منظور شناسايي فون نماتدهاي منطقه كهق واقع در شمال شهرستان مراغه، طي فصول بهار، تابستان و پاييز سال‌هاي 1393 و 1394 تعداد 70 نمونه خاك از اين منطقه جمع‌آوري گرديد. پس از انتقال نمونه‌ها به آزمايشگاه، نماتدهاي موجود در آن‌ها با استفاده از روش تلفيق الك و سانتريفيوژ استخراج و بعد از تثبيت به روش دگريس به گليسيرين خالص انتقال داده شدند. از نماتد‌ها اسلايد‌هاي ميكروسكوپي دائمي تهيه گرديد. سپس به‌وسيله‌ ميكروسكوپ نوري و لوله ترسيم، خصوصيات ريخت‌شناختي و ريخت‌سنجي آن‌ها مورد بررسي قرار گرفت. شناسايي جنس‌ها و گونه‌هاي نماتدها با استفاده از منابع معتبر و كليدهاي موجود انجام و گونه‌هاي Amplimerlinius globigerus، Criconemoides informis، Mesocriconema antipolitanum، Ogma cobbi، Pratylenchus neglectus، P. thornei، Pratylenchoides erzurumensis، Xiphinema index، X. pyrenaicum، Xiphinema sp. و Zygotylenchus guevarai از نماتدهاي انگل گياهي تشخيص داده شد.

Background and Objectives Plant parasitic nematodes are distributed in all agricultural soils and attack nearly all crops, damage and cause disease. In studying biology, management and other aspects of plant parasitic nematodes, their precise identification should be carried out up to species level. Kahaq region, Maragheh, East Azarbaijan province, is a natural ecosystem and under cultivation of agricultural crops as well. Fruit trees such as walnut, almond, apple, quince and crops like wheat, barley, chickpea and fruitless trees as spruce and willow are grown in the region. Due to the paucity of previous studies the current study set out for the identification of nematode fauna in soils of this region. Materials and Methods In order to identify plant parasitic nematodes, 70 soil samples were collected from the rhizosphere of different vegetations in Kahaq region, Maragheh, East Azarbaijan province during 2014 and 2015. The samples were transferred to laboratory and nematodes extracted by centrifugal flotation technique were transferred to anhydrose glycerin according to the modified De Grisse (1969) method. Permanent slides were prepared from the extracted nematodes and some cross sections were also made from different parts of some nematode bodies if needed. The nematodes were studied under light microscope. The morphometric data were taken using a drawing tube attached to the microscope. Drawings were done using Corel DRAW X7 software. Pictures were taken using DP50 digital camera attached to the microscope. Results The results of this study led to the identification of Amplimerlinius globigerus, Criconemoides informis, Mesocriconema antipolitanum, Ogma cobbi, Pratylenchus neglectus, P. thornei, Pratylenchoides erzurumensis, Xiphinema index, X. pyrenaicum, Xiphinema sp. and Zygotylenchus guevarai. Discussion Morphological and morphometric characteristics of two plant parasitic nematodes out of 11 identified species were described in details. Ogma cobbi shows much similarity with O. nemorosus, but the latter differs from the former species because of fewer number of body annuli (45-54 vs 58-61), shape of scales in mid-body (triangular, with rounded tip vs rather acute), empty spermatheca vs full of sperm, occasional presence of smaller scales between rows, especially on posterior half of body (vs not). Xiphinema sp. becomes more similar to X. brevisicum, but is separated from it by lower a value (53-67 vs 72.5-98), cˊ value (1.5-2 vs 2.2-3.1), greater odontostyle length (77-86 vs 57-65 μm) and shorter tail length (27-31 vs 35-47 μm). It also differs from other species of the genus and, hence, considered as an undescribed species.