ارزیابی شاخص‌های بیماریزایی در تعیین مقاومت ارقام انار به نماتد ریشه گرهی Meloidogyne incognita

Pomegranate is one of the most important fruits of tropical region which has special position in the garden products. Iranian pomegranate is unrivaled in the production of non-oil products due to its high quality, beautiful appearance and bright color. Root-knot nematodes (Meloidogyne spp.) are serious pathogens in pomegranate and have been reported in most of the countries where pomegranate is cultivated. Pomegranate yield reduction due to root knot nematode in India has been reported as 17.3%. In this study, pathogenicity factors (number of galls, number of egg masses, and number of eggs in egg mass) of 25 commercial pomegranate cultivars and a native genotype were measured after 4 months of inoculation by the Meloidogyne incognita. The resistance index was determined by Quesenberry (RI=√(gall index2+egg mass index2)) scale which includes the egg mass index and gall index (0-0.9 immune, 1-1.9 very resistant, 2-2.9 resistant, 3-3.9 relatively resistant, 4-4.9 moderate resistance, 5-5.9 relatively susceptible, 6-6.9 sensitive, and 7 very susceptible). Analysis of variance in treatments had significantly difference at level of 1%. Mean comparison was based on Duncan's test. The highest number of galls showed in Farough, Shirine Shahvar and Malase Torsh. The highest number of egg masses showed in the roots of Farough, after that Shirine Shahvar, Malase Torsh and Zardeh Anar respectively. There is no significantly difference between Malase Saveh, Bajestani Khorasani and Kedru cultivars, and they were after the previously mentioned cultivars. The lowest number of egg masses was in the native genotype of Qaemshahr and the rest of the cultivars are between these two groups. The result of mean comparison of the number off egg in egg mass showed the highest in Farough and Zardeh Anar cultivars and showed the lowest in the native genotype of Qaemshahr and Shishekape Ferdows. Also, Farough cultivar had the highest egg mass. In the results of the resistance level of cultivars, native genotype of Qaemshahr was identified the only resistant cultivar by resistance index 2.5, then Ardestani Khorasani was reported moderately resistant cultivar by resistance index 4.6. Goltafti, Dokhtar Hamumi, Glubarik, Naderi Natanz Kashan, Shirine Shahvare Yazdi, Daneh Siyah, Bajestani Khorasani, Shishekape Ferdows, Alake Saveh, Malase Saveh and Ameneh Khatuni were introduced relatively susceptible. Malase Daneh Ghermeze Yazdi, Robabe Neyriz, Kedrou, Malase Yazdi, Mah Velate Khorasan, Malase Daneh Ghermez, Meykhooshe Post Nazok, Tough Gardane Yazdi and Ghojagh Ghom were identified susceptible cultivars and eventually Zardeh Anar, Shirin Shahvar, Malase Torsh and Farough were introduced high susceptible.