INTRASPECIFIC AND INTERSPECIFIC VARIATION OF ROOT-KNOT NEMATODES, MELOIDOGYNE SPP., WITH REGARD TO RESISTANCE IN WILD TUBER-BEARING SOLANUMSPECIES

Genotypes of wild Solanum species were tested to determine the level o f resistance to root-knot nematodes and to detect the presence of viru lent populations within Meloidogyne chitwoodi, M. fallax and M. hapla. High resistance to all tested populations of il M. chitwoodi and M. f allax was observed in genotypes of Solanum bulbocastanum, S. hougasii, S. cardiophyllum and S. fendleri. Some genotypes of S. chacoense and S. stoloniferum showed moderate resistance to M. fallax, but no or les ser resistance to M. chitwoodi. There was little variation in virulenc e in populations of M. chitwoodi and M. fallax found on resistant plan ts. In contrast, large differences in virulence toward resistant genot ypes of S. bulbocastanum, S. hougasii, S. chacoense, S. gourlayi, S. s parsipilum and S. spegazzinii were observed between four populations o f M. hapla. It was found that resistance to M. chitwoodi, M. fallax an d/or M. hapla is not linked to resistance to the nematode species adap ted to high temperature, i.e.,M. incognita, M. arenaria and M. javanic a.