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POSTERS: Host resistance screening

Identification of orange fleshed sweet potato clone resistant to three different species of rootknot nematodes
Alexandre Furtado Silveira Mello - Embrapa Vegetables. Raquel Souza- EMBRAPA, Maria Silva- Embrapa Vegetables, Jadir Pěnheiro- Embrapa Vegetables, Danielle Biscaia- Embrapa Vegetables, Amanda Macedo- Embrapa Vegetables, Alexandre Barbosa- Embrapa Vegetables

One of the main obstacles to food production is the damage caused by nematodes. On sweet potato symptoms are associated to reduction of fibrous roots, plant growth and yield loss. The objective of this work was to characterize the resistance level of four sweet potato clones to the Meloidogyne javanica, M. incognita and M. enterolobii. In addition to the clones, four sweet potato commercial cultivars, and one susceptible tomato control was used. The experiment was installed in 5L plastic pots and conducted under greenhouse conditions on a completely randomized design, with six replications. Soil was infested with 5000 eggs and eventual second stage juveniles (J2) from each species on separate pots. Plants were evaluated 47 days after soil infestation. The classification of resistance levels was performed according to the Reproduction Factor (RF), gall index (GI), egg mass index (IMO) and number of eggs per gram of root (NEGR). The four clones were classified as resistant according to the FR of M. javanica and M. incognita. The other parameters evaluated were also statistically different from the susceptible sweet potato commercial cultivars and the tomato cultivar. One of clones (BD 74) presented a FR of 0,14 and was considered also resistant to M. enterolobii since the threshold for resistance is FR lower than one. This finding is very relevant because despite being present in Brazil since 2001 few species and cultivars are resistant to M. enterolobii.