Studies on genetic resistance to bacterial wilt (Pseudomonas solanacearum e.f. Smith) and root-knot nematode (Meloidogyne incognita Kofold and White, 1919; Chitwood, 1949) in tomato(Lycopersicon esculentum Mill.)

Abstract

Present study was undertaken to study the inheritance of combined resistance to bacterial wilt and root-knot nematode in tomato, to study the interaction of these soil borne pathogens on the resistant genes present in the host genotype and to identify a broad spectrum resistant source of wilt amongst known lines/varieties. The results showed that F1s of parents having dominant sources of resistance to wilt and root-knot nematode were resistant to both the diseases in the field. The combined resistance to both the diseases was inherited digenically in ‘BWR-1’ crosses. The interaction between the pathogens had modified the genetic ratio in the crosses. The sequential inoculation (N+B and B+N) of both pathogens, in the pots, showed that the digenic ratio was modified to 9:3:4 irrespective of the sequence. The interaction between the pathogens was more severe in ‘BWR-1’ hybrids as a result of simultaneous inoculation. On the other hand, ‘CRA-66- Sel-A’ hybrids could withstand the interaction because at the seeding stage partial dominance to wilt was operational in them. The significant correlation between ooze index and gall index proved that the nematodes predisposed the plants to bacterial wilt. The lines selected for resistance to bacterial wilt in Hessaraghatta showed differential response to isolates of P. solanacearum from Maharashtra, Kerala and Chethalli. The best F1 hybrids for fresh market were ‘BWR-1’ x ‘Rossol’, ’83 BWR 12-2’ x ‘IHR-998’, ‘83 BWR-120’ x ‘Patriot’ and ‘MITA-668’ x ‘83 BWR-120’.