Psyhcrotolerant Bio-inoculants and Their Co-inoculation to Improve Cicer arietinum Growth and Soil Nutrient Status for Sustainable Mountain Agriculture

Abstract

Chickpea (Cicer arietinum) is the most important pulse crop across the Himalayan regions, characterized with extreme as well as nutritionally deficient habitats. Considering the adverse effects of chemical fertilizers, bio-inoculants should be encouraged as natural “nutrient” resource. Two indigenous bio-inoculants i.e. psychrotolerant diazotroph Pseudomonas palleroniana strain N26 and phosphate solubilizer Pseudomonas jesenii strain MP1 were evaluated for their plant growth promoting potential against chickpea in organic and conventionally managed soils under natural net house conditions. Furthermore, denaturing gradient gel electrophoresis (DGGE) and real-time PCR (qPCR) techniques were used to analyse the microbial diversity and dynamics during the experiment. Comparative agronomical and biochemical crop parameters revealed that organic soils co-inoculated with bio-inoculants have 24.69%, 37.42%, 100.65%, 83.33%, 60.86% and 103.05% improvement in plant shoot length, root length, dry weight, fresh weight, chlorophyll content and nitrate reductase activity, respectively, over the control. Similarly, organic carbon, nitrogen, phosphorus and potassium content of co-inoculated soils was at par with their respective controls. Moreover, qPCR and DGGE-based soil bacterial dynamics unveiled the persistence of both the strains until the end of crop maturity without affecting the native micro-flora. Conclusively, bio-inoculants alone were found sufficient to fulfil crop nutritional requirement. Moreover, their co-inoculation showed significant potential for chickpea growth and development under organically managed soils, and therefore, additional incentive in their bio-formulation will be a step forward towards zero budget mountain farming.