Protective and Curative Influence of Plant Growth Promoting Rhizobacteria on the Development of M. incognita Juveniles

Abstract

In Pakistan, the low yield of eggplant is ascribed to legions of biotic constraints. Among biotic restraints, root-knot nematodes, Meloidogyne spp. are economically very important and cause losses to the tune of $ 125 billion per year throughout the world. In this experiment, efficacy of PGPRs was checked as protectant and curative against M. incognita under greenhouse conditions. Three weeks old seedlings of eggplant (cv. Dilnasheen) were transplanted singly in each 20cm-dia. earthen pots filled with two kg sterilized soil. Ten days after seedlings transplantation, each pot was inoculated with PGPRs (B. subtilis, P. fluorescens, A. chroococcum, Azospirillum sp, and R. leguminosarum) having 10⁷ cfu/ml @ 30 ml per plant with 5% sugar solution. One week after of PGPR application, 2000 freshly hatched juveniles of M. incognita (contained in 15 ml of water) were inoculated in the root zone. While in curative application ten days after transplantation of seedlings, 2000 freshly hatched juveniles (contained in 15 ml of water) were inoculated in the root zones. One week of after J2s inoculation, PGPRs having 10⁷ cfu/ml were applied to pots @ 30 ml per plant with 5% sugar solution. Plants without PGPR and J2s inoculation were kept as control. The experiment was arranged in Completely Randomized Design with ten replicates. The effectiveness of PGPRs was evaluated against M. incognita, as protective and curative applications, all the PGPRs caused significant reductions in nematode infestations. When the comparison was made between the protective and curative applications, it was found that the protective application was better than the curative application of PGPRs. Galls per root system on eggplant were significantly lower in protective application than the curative application over control. Similar trends were observed in other parameters viz. number of females, egg masses, soil and root population and reproduction factors of nematodes.