بررسی تراکم جمعیت اولیه نماتدهای Meloidogyne javanica و M. incognita بر گیاه بامیه

Due to the wide host range and interaction of root knot nematodes (Meloidogyne spp.) with other plant pathogens, these nematodes are considered as the most important plant parasitic nematodes. Okra (Abelmoschus esculentus (L.) Moench) is one of the most popular crops worldwide, especially in tropical and subtropical regions. Root knot nematodes are one of the most harmful pathogens of okra and cause severe damage to plant growth and flower formation. In the present study, the effect of initial population (Pi) density of M. javanica and M. incognita were evaluated on okra growth indices and infection to nematode, under greenhouse condition. Seeds of okra (cv. Clemson Spineless) were sown in 3 kg plastic pots containing equal amount of farm soil, sand and cow manure. Four-leaf stage seedlings were inoculated by different Pi density of nematodes viz. 0.125, 0.25, 0.5, 1, 2, 4, 8, 16 and 32 eggs and second stage juveniles (J2s) gr-1 soil. The experiment was conducted in a completely randomized design with four replications. The pots were kept under controlled condition at 27 ± 3°C and were regularly irrigated. Plants were harvested 60 days after inoculation and plant growth indices of the plants as well as the nematode population indices were evaluated. Results showed that the highest damage to the plants was observed in those treatments with the highest initial population density of the both nematodes caused damage. Growth indices of okra were decreased by increasing in Pi density of every one of nematodes. As compared to control, the highest Pi density of M. incognita reduced the shoot length and fresh and dry weight of shoot by 52, 64 and 60%, respectively and in case of M. javanica, the highest initial population density caused the reduction of 56%, 65% and 64%, respectively. It was observed that at the highest Pi density of M. incognita, the number of eggs, galls and egg masses per root system and the number of J2s per pot were respectively increased 2.9, 5, 3.9 and 27.8 fold,. In case of M. javanica, the rate of increase were 2.3, 3.9, 3 and 27.7 fold, respectively. For the both of nematode species. The results of this study showed that okra crop has high susceptibility to both common root knot nematodes, even at low initial population density.