PATEL, B. N.PATEL, KAMLESH A.2018-05-132018-05-131993http://krishikosh.egranth.ac.in/handle/1/5810045407Investigation was carried out to study the effect of interaction between TMV and root-knot nematode [Meloldogyne incogni ta (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood] on plant growth, nematode populations and chemical constituents of bidi tobacco (Nicot iana tabacum L.) var. Anand 119. Results revealed that the growth parameters, viz., leaf number, plant height, leaf length, width and thickness, leaf weight, stem weight and root length barring root weight were more or less reduced due to combined infection of TMV and root-knot nematode when compared with control as well as with single infection with either pathogen. Between the two pathogens, infection with TMV had more impact on the growth parameters than the nematode infection. Maximum reduction in the plant growth was recorded due to simultaneous infection with TMV and rootknot nematode thus suggesting that these pathogens had synergistic effect on growth of bidi tobacco. Root-knot Index and nematode population in the soil as veil as in the roots were increased in the treatment having the simultaneous infection as well as in the treatments where nematode inoculations preceded virus inoculations when compared with nematode infection alone. Combined infection of TMV and root-knot nematode was also found to result in accelerated reduction of protein nitrogen, total nitrogen and nicotine contents and a greater imprcvement in total sugars content over singly infected plants. Results of a study to determine the possible role of root-knot nematode in the development of TMV infection through tobacco roots indicated that maximum incidence of mosaic disease was recorded when abplication of nematode inoculum preceded the incorporation of the virus inoculum in the soil. The disease had also appeared relatively early in this treatment combination. The results of this study ultimately suggest that root-knot nematode would play an important role in increasing the incidence of mosaic in fields in which mosaic infected plant debris has not completely decomposed before transplanting of bidi tobacco seedlings.enPLANT PATHOLOGY, AGRICULTUREA STUDYThesis