The prevalence of Meloidogyne incognita, a severe root-knot nematode, is alarmingly high in the production of ginger-a main cash crop of Himachal Pradesh, a Himalayan state of India. In order to control this through natural means, the nematicidal potential of plant growth-promoting rhizobacteria (PGPR) against M. incognita was analyzed. This is an effective alternative solution to manage nematode incidence as compared to hazardous chemicals under protected and field cultivation of ginger. In the present study an attempt has been made to isolate, characterize, and identify potential rhizobacteria associated with ginger rhizosphere and endosphere. In total, 169 bacterial isolates were isolated from ginger (Zingiber officinale) rhizosphere and endosphere of 4 different sites of Sirmaur district, screened out for multifarious PGP traits showing positive results. The combined cluster analysis and 16S rRNA genotypic analysis of selected bacterial isolates revealed that Serratia marcescens FS-23, Pseudochrobacter sp. GS-15, Stonotrophomonas pavanii HER-9, Pseudomonas brassicacearum HER-20 and Serratia marcescens IS-2 exhibited highest PGP traits. All tested bacterial isolates were capable of exerting a significant effect on mortality of juvenile M. incognita ranging upto 40-90% in laboratory experiments. Further a consortium of these screened isolates showed 86.67% reduction in gall formation by M. incognita in lab conditions. The remarkable increase to 93.24% with 138.73 q/ha with application of charcoal based bio-formulation of consortium without adding any chemical fertilizer was observed in field trials of Nohradhar of Sirmaur district. An alternative choice as a biocontrol agent as well as for PGP activities, the novel and most robust isolate Serratia marcescens IS-2 had revealed to have a variety of bioactive metabolic products with abilities against nematodes, bacteria, and fungi.
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