Exploring Indigenous Nitrogen-fixing Bacteria from Apple Orchard Soils of Kashmir Valley, India for Sustainable Biofertilizer Development
Misbah Rasool
Division of Basic Science and Humanities, Faculty of Agriculture, SKUAST-K, Wadura (J&K)-193201, India.
Z. A. Baba
Division of Basic Science and Humanities, Faculty of Agriculture, SKUAST-K, Wadura (J&K)-193201, India.
Ishrat Gull *
Division of Soil Science and Agricultural Chemistry, Faculty of Agriculture, SKUAST-K, Wadura (J&K)- 193201, India.
M.H Chesti
Division of Soil Science and Agricultural Chemistry, Faculty of Agriculture, SKUAST-K, Wadura (J&K)- 193201, India.
Tahir Sheikh
Division of Agronomy, Faculty of Agriculture, SKUAST-K, Wadura (J&K)-193201, India.
Faheem Jeelani Wani
Division of Economics and Agriculture Statistics, Faculty of Agriculture, SKUAST-K, Wadura (J&K)-193201, India.
Najeeb Ul Rehman Sofi
Mountain Research Centre for Field Crops, Khudwani, SKUAST-K, J&K-192231, India.
Tanzeela Habib
Division of Soil Science and Agricultural Chemistry, Faculty of Agriculture, SKUAST-K, Wadura (J&K)- 193201, India.
Piyush Kumar *
Division of Plant Pathology, Faculty of Agriculture, SKUAST-K, Wadura (J&K)-193201, India.
*Author to whom correspondence should be addressed.
Abstract
The growing environmental concerns associated with the excessive use of synthetic fertilisers have accelerated the search for sustainable microbial alternatives in agriculture. This study was carried out in 2024 at the Biofertilizer Laboratory, Faculty of Agriculture (FoA), SKUAST-Kashmir, with the aim of isolating and characterizing multifunctional nitrogen-fixing bacterial (NFB) strains from the rhizosphere soils of apple orchards in the Kashmir Valley, India, and evaluating their potential as plant biostimulants. A total of 122 fast-growing bacterial strains were isolated from 90 rhizosphere soil samples collected across ten apple-growing districts. All isolates were subjected to quantitative nitrogen fixation assays, and five isolates demonstrating the highest N₂ fixation were selected for further assessment of nutrient solubilisation and plant growth-promoting traits. All five isolates demonstrated the ability to solubilize phosphate, potassium, and zinc. Assessment of their functional properties revealed positive ammonification, catalase, peroxidase, and gelatin hydrolysis activities among the five isolates. Furthermore, these isolates exhibited important plant growth-promoting properties, including siderophore production, ACC deaminase activity, indole-3-acetic acid (IAA) production, and antagonistic activity against Fusarium spp. Based on their overall multifunctional performance, NFB(Ar)3 was identified as the most promising isolate and selected for molecular identification. 16S rRNA gene sequencing revealed 99.33% similarity to Azotobacter chroococcum, supporting its taxonomic identification. These findings highlight the potential of NFB(Ar)3 as an eco-friendly biofertilizer candidate for sustainable agriculture and for reducing dependence on synthetic inputs.
Keywords: Apple orchard soils, bio-stimulants, biofertilizer, Nitrogen-fixing Bacteria (NFB), plant growth-promoting rhizobacteria, rhizosphere, sustainable agriculture