Indigenous plant-growth-promoting rhizobacteria and chemical fertilisers: impact on wheat (Triticum aestivum) productivity and soil properties in North Western Himalayan region

Abstract

High levels of crop productivity cannot be sustained by chemical fertiliser application alone. In order to mitigate this, a 2-year study was conducted to test the effects of combined application of indigenous plant-growth-promoting rhizobacteria (PGPR) and chemical fertilisers on productivity of wheat and soil properties. Ten morphologically distinct indigenous PGPR isolates from wheat roots and rhizosphere were evaluated at Solan, Himachal Pradesh, India, during 2013–14. Three PGPR isolates (B2, SIR1 and BIS2) with maximum PGP traits were screened at different doses of nitrogen (N) and phosphorus (P) (80%, 60% and 40% of recommended fertiliser dose, RFD) under net-house conditions. Two isolates, B2 (Serratia sp.) and SIR1 (Bacillus subtilis), along with the optimum NP dose (i.e. 80% RFD) were selected for field experimentation, which was performed over two consecutive years, 2014–16. Combined application of 80% RDF of NP with PGPR (B2) significantly increased wheat yield by 9.4%, number of tillers per plant by 28.03%, grain number per spike by 19.61%, 1000-grain weight by 10.5%, and biomass by 9.2% relative to the uninoculated control with 100% RFD. Soil properties in the terms of available N, P and potassium, microbial biomass carbon, soil enzyme activities and population of phosphate-solubilising bacteria in the wheat crop were significantly increased by the combined application of bacterial inoculants with 80% RFD of NP in both years over the uninoculated control. Therefore, the results revealed the potential of indigenous PGPR isolates to supplement ~20% of NP fertilisers without hampering the soil fertility and productivity of wheat.