Resistance of sweet potato clones to Meloidogyne java']javanica

The objective of this study was to evaluate and select clones of sweet potato (Ipomoea batatas) for their resistance to Meloidogyne javanica. Sixty-tree clones were evaluated, among the commercial cultivars (Brazlandia Rosada, Brazlandia Branca, Palmas, Princesa and Coquinho) plus the tomato cv. Santa Clara (susceptible to Meloidogyne spp.). The stems were planted in expanded polystyrene trays with 72 cells with commercial substrate and maintained in a greenhouse. The experimental setup was a randomized blocks design with three replications and six plants per plot. The pathogen inoculation was carried out 30 days after the stems planting, and after 75 days the stems were removed from the polystyrene trays and their roots were washed. Extraction and counting of nematode eggs were carried out. Classifying resistance levels was carried out based on reproductive factors (FR) and reproduction index (IR). Of the 63 clones 71.43% were identified as resistant by the reproduction factor and 82.51% were classified as highly resistant or very resistant by reproduction index. When the both classification criteria were used, 71.43% of sweet potato clones were classified as resistant to Meloidogyne javanica.