Host suitability of Solanum torvum cultivars to Meloidogyne incognita and M. java']javanica and population dynamics

Several experiments were carried out to assess the performance of commercial Solanum torvum cultivars against the root knot nematodes Meloidogyne incognita and M. javanica in Spain. The response of S. torvum rootstock cultivars Brutus, Espina, Salutamu and Torpedo against M. incognita and Mi-1.2 (a)virulent M. javanica isolates was determined in pot experiments, and of 'Brutus' to an N-virulent isolate of M. incognita, compared with that of the eggplant S. melongena 'Cristal'. The relationship between the initial and final population densities of M. javanica on ungrafted and grafted 'Cristal' onto the S. torvum 'Brutus' was assessed, together with the effect on dry shoot biomass. Finally, the population growth rate and the resistance level of the four S. torvum cultivars against M. incognita was assessed under plastic greenhouse conditions in two cropping seasons. All S. torvum rootstocks responded as resistant to the M. incognita isolates and from highly resistant to susceptible against M. javanica isolates. The maximum multiplication rates of M. javanica on the ungrafted or grafted eggplant were 270 and 49, respectively, and the equilibrium densities were 1318 and 2056 eggs and J2 per 100 cm(3) soil, respectively. The tolerance of the ungrafted eggplant was 10.9 J2 per 100 cm(3) soil, and the minimum relative dry shoot biomass was 0.76. The population growth rate of M. incognita on eggplant cv. Cristal differed from that of the S. torvum cultivars in both cropping seasons. These results suggest that S. torvum is a valuable rootstock for managing the two Meloidogyne species irrespective of the (a)virulence status.