ارزیابی مقاومت برخی ارقام گوجه‌فرنگی نسبت به نماتد ریشه‌گرهی meloidogyne javanica در شرایط گلخانه

نماتد‌های ریشه‌گرهی، از مهم‌ترین نماتدهای انگل گیاهی در سطح جهان می‌باشند که اغلب محصولات زراعی را مورد حمله قرار می‌دهند. استفاده از ارقام متحمل یا مقاوم به نماتد، یکی از روش‌های موثر در کاهش خسارت ناشی از نماتدهای ریشه‌گرهی است. در این مطالعه با هدف ارزیابی سطح مقاومت تعدادی از ارقام گوجه‌فرنگی شامل alyste f1، aryza f1، early urbana، rutgers و mobil ( هلند و مجارستان)، نسبت به حمله‌ی نماتد ریشه‌گرهی meloidogyne javanica، در قالب پنج تکرار و در دو حالت مایه‌زنی و عدم مایه‌زنی در شرایط گلخانه‌ای، برخی شاخص‌های رشدی گیاه (وزن تر و خشک ریشه، وزن تر و خشک بخش هوایی، طول ریشه، ارتفاع گیاه و وزن تر و خشک کل) و تولیدمثلی نماتد (تعداد گال و توده تخم نماتد در گرم ریشه و کل ریشه، تعداد تخم موجود در توده تخم، تعداد لاروهای سن دوم موجود در خاک، جمعیت نهایی نماتد و فاکتور تولیدمثلی) بررسی شده است. نتایج نشان داد که رقم alyste f1، با کم‌ترین تعداد گال ریشه، توده‌تخم، تخم و لارو سن دوم موجود در خاک و به تبع آن کم‌ترین میزان جمعیت نماتد، به عنوان رقمی نسبتا مقاوم شناخته شد. از نظر صفات رویشی گیاه نیز مشخص گردید رقم alyste f1، در بالاترین سطح، از لحاظ ویژگی‌های رویشی بوده و از تفاوت آماری معنی‌داری نسبت به دیگر ارقام برخوردار بوده است. نتایج هم‌چنین نشان داد که ارقام موبیل هلند، موبیل مجارستان، ارلی‌اربانا، aryza f1 و روتگرس نسبت به نماتد ریشه‌گرهی، براساس فاکتور تولیدمثل (rf) و شاخص گال در زمره‌ی ارقام خیلی حساس طبقه‌بندی شدند. براساس ویژگی‌های زایشی نماتد مشخص گردید که ارقام موبیل هلند، موبیل مجارستان و ارلی‌اربانا، بیش‌ترین جمعیت نماتد و بالاترین فاکتور تولیدمثل را به خود اختصاص دادند اما از لحاظ ویژگی‌های رویشی، رقم روتگرس در بین ارقام، از تاثیرپذیری بیش‌تری برخوردار بود. نتایج تجزیه‌ خوشه‌ای براساس مجموع صفات رویشی گیاه و تولیدمثلی نماتد نیز نشان داد که رقم alyste f1 به صورت مجزا از دیگر ارقام قرار گرفت. در نهایت براساس مجموع نتایج حاصل از این پژوهش، رقم alyste f1، به عنوان مقاوم‌ترین رقم شناخته شد.

Evaluation of Resistance to Root-Knot Nematode, Meloidogyne javanica, in Some Tomato Cultivars under Greenhouse Conditions

Introduction: The rootknot nematodes of the genus Meloidogyne are highly adapted, obligate plant parasites, consisting of nearly one hundred valid species, and are considered the most economically important group of plantparasitic nematodes. The control of root knot nematodes has been sought by the use of nematicides, resistant varieties, crop protection and organic amendments. Because of toxicity of nematicides for environment, human health and wild life, application of them are restricted. Identification of genes responsible for resistance to rootknot nematode and their mode of actions have attracted a lot of attentions to develop resistant cultivars. Resistance in the plant species is often due to the presence of specific genes. In resistant cultivars, resistance genes can prevent or suppress one or more stages of nematode infection cycle. In fact, in response to nematode infection, resistance genes can prevent or suppress one or more stages of nematode infection process. In the most incompatible interactions, depending on the mechanism of resistance, the root galls are reduced or eliminated at the sites of infection. Assessment of resistance to the rootknot nematodes in different tomato cultivars is helpful for selection of suitable cultivars with satisfying plant growth and nematode tolerance traits for suitable management of the rootknot nematode. Thus, in the present study we evaluate the response of some tomato cultivars for resistance to rootknot nematodes, Meloidogyne javanica, in greenhouse conditions.Materials and Methods: In this study, the nematode population was obtained from roots of tomatoes collected at a glasshouse in Tirtash–Mazandaran, Iran.The rootknot nematode were purified and multiplied on tomato cv. Early Urbana plants. Then the nematode species were identified based on morphological and molecular methods. The seeds of ALYSTE F1, ARYZA F1, Rutgers, Early Urbana, Dutch Mobil and Hungarian Mobil tomato cultivars were spawned in equal proportions of cocopit, perlite and vermiculite and irrigated for 3 weeks. Then, the seedlings were transferred to the pots containing mixture of sterile soil, sand and vermiculite (1:1:1) with 9 cm diameter. After 2 weeks, the seedlings were inoculated with 3000 second stage juveniles (J2s) of M. javanica. The pots were kept for 70 days at 2433°C and 50% relative humidity. Resistance evaluation was based on plant growth and nematode reproduction indices. Growth indices were fresh and dry weight of root and aerial part, root length, plant height and total fresh and dry weight and nematode reproductive indices were number of galls and egg masses/g root and total root, eggs/egg mass, eggs/root, J2s /soil, final nematode population and reproduction factor (RF) were measured and recorded. The experiment was carried out in a completely randomized design with 5 replicates in the both of inoculated and noninoculated with nematode. Data were analyzed in Minitab version 17. The means were compared by using Fisher,s LSD. Also to determine the resistance level, resistance index (RI) and reproduction factor (RF) were calculated. The RI is depended to frequency of the gall and egg mass index in the root. To determine Gall Index (GI) and Egg mass Index (EI), 0= no galls or egg masses, 1= 1 to 2, 2= 3 to 10, 3= 11 to 30, 4= 31 to 100 and 5= more than 100 were considered, in the following for RI, 00.9= immune, 11.9= highly resistant, 22.0= resistant, 33.9= moderately resistant, 44.9= intermediate, 55.9= moderately susceptible, 66.9= susceptible  and more than 7= highly susceptible. The reproductive factor (RF) of the rootknot nematode in the different genotypes was obtained by dividing the final and initial population densities of the nematode (RF = Pf/Pi).Thus, RF≤1, GI≤2 = resistant; RF≤1, GI>2= moderately resistant; RF>1, GI≤2= tolerant and RF>1, GI>2 susceptible.Results and Discussion: This study results showed that ALYSTE F1, had the lowest number of gall, egg mass, second stage juveniles and consequently the lowest nematode population and was recognized as moderately resistant cultivar. In terms of the growth indices, ALYSTE F1 also had the highest growth characteristics and contained a significant difference with other cultivars. Totally, Rutgers, ARYZA F1, Dutch Mobil, Hungarian Mobil and Early Urbana varieties were introduced as highly susceptible cultivars based on RF and GI. However, Dutch Mobil, Hungarian Mobil and Early Urbana had the highest nematode population and reproduction factor (RF). In terms of the growth traits, the results showed that Rutgers, as a highly susceptible cultivar, was more impressible than other cultivars followed by Dutch Mobil. The cluster analysis based on the sum of the plant growth and nematode reproductive traits showed that ALYSTE F1 cultivar was distinct from the other cultivars. Thus, the cluster analysis confirmed the results of comparison of the average of the plant growth and nematode reproductive traits.Conclusion: Based on the results of this study, ALYSTE F1 was identified as a moderately resistant cultivar to the root knot nematode, M. javanica. and the others were highly sensitive to the nematode.