Indigenous plant growth promoting rhizobacteria: potential green alternative for capsicum productivity under mid-hill conditions of north-western Himalayan region

Plant growth promoting (PGP) potential of rhizospheric and endophytic bacterial isolates of capsicum (Capsicum annuum L) obtained from different agro-climatic zones of Himachal Pradesh was studied. Total of 10 isolates (RS₁-RS₁₀) were morphologically and physiologically characterized and tested for multifarious PGP traits viz phosphate solubilization, auxin and siderophore production. Nutrient broths having 1.5 OD at 540 nm were used as inoculum and 4 hours as seed imbibition time period. Only six isolates (RS₂, RS₃, RS₄, RS₇, RS₈, RS₁₀) possessing maximum of PGP traits were evaluated for seed germination and seedling growth studies under controlled conditions. Isolates were tried singly as seed inoculation in Completely Randomized Block Design replicated thrice. All the selected isolates were Gram positive rod, differed in colony morphology, showed optimum growth at 35°C and 7 pH and possessed various PGP traits. Maximum seed germination (84.4%), increase in shoot length (41.54%), shoot biomass (41.46%), root length (69.64%), root biomass (42.85%) over uninoculated control were noted for RS₇ isolate inoculated seeds. The RS₂ isolate inoculation in general had the similar effect of studied plant parameter. Present investigations focus on potential use of isolate RS₇ (Bacillus spp) and RS₂ (B subtilis) as biofertilizer for capsicum under north-western Himalayan region.