National Symposium on Strategic Issues in Plant Pathological Research held at Department of Plant Pathology, CSK HP Krishi Vishvavidayalaya, Palampur on November 24–25, 2011
Apple replant disease is a complex syndrome causing necrotic lesions on feeder roots, stunted tree growth and reduced cumulative yields. The aim of the study was to select and develop more efficient plant growth promoting rhizobacterial strain of fluorescent Pseudomonas sp. for management of replant problem. The ten fluorescent Pseudomonas sp. isolated from rhizosphere of normal and replant site of apple from Shimla Distt. (H.P)., were screened out for plant growth promoting activities in vitro such as antifungal activity against different plant pathogens (viz., Dematophora sp., Fusarium sp., Phytophthora sp., Pythium sp. and Sclerotium sp.), phosphate solubilization, siderophore production, proteolytic activity, HCN and ammonia production. The maximum solubilization of inorganic phosphate was shown by Pn-2-kho (410 µg/ml) and An-2-nali (370 µg/ml) and both these isolates also showed antifungal activity against one or the other test fungi. Out of ten isolates, two isolates (An-2-nali and Pn-2-Kho) were selected on the bases of their high plant growth promoting activities and their identity was established by 16S rRNA analysis. The selected isolates were used to study their effect on apple plants planted in replant area of Deola (Distt. Shimla). The effects of these two Pseudomonas strains on plant and soil parameters were evaluated. The results showed that both the isolates caused significant increase in various plant and soil parameters alongwith reduction in disease incidence after the cyclic treatment of these strains.
