Salt Tolerant Indigenous Zn Solubilizing Bacteria Isolated from Forest Organic Soils Promotes Yield and Root Growth in Oryza Sativa under Zinc Deficient Alluvial Soil

Abstract

The present study conducted to identifying and characterizing the efficient Zn solubilizing rhizobacteria isolated from chickpea and peas rhizosphere owing distinct plant growth advancing qualities for zinc-inadequate alluvial soil. Out of ten, Four strains ZnJ11, (Klebsiella pneumonia- MT509804), ZnJ10 (Acinetobacter calcoaceticus- MT509803), ZnJ15A (Acinetobacter pittii- MT509805), and ZnJ2A (Pantoea agglomerans- MT509806) were selected using basal medium contained insoluble Zn minerals such as ZnO and ZnPO₄ at concentrations of 2000 µg/mL. In qualitative assay, ZnJ11 showed maximum zinc solubilization efficiency (SE: 525 ± 2.9 and pH-7.5), followed by ZnJ10 showed (SE: 383 ± 3.1 and 329 ± 3.2, pH-7.5) in all three Zn sources, then ZnJ15A and ZnJ2A exhibited (SE: 306 ± 2.2 and 206 ± 1.7) respectively. Contrary to plate assay, zinc solubilization in liquid medium quantified by AAS also revealed efficacy of all the strains. Bacterial growth and Zn solubilization at variable salt concentration (0–10%) and pH (4.5–10) was measured that showed Klebsiella sp. tolerate (8% & 6.5–8.5), Acinetobacter calcoaceticus (6% & 6.5–10), Acinetobacter pittii (10% & 6.5–10) and Pantoea sp. (8% & 5.5–10) respectively. In addition, all strains were showed different degree of susceptibility to tested antibiotics at variable concentrations. Simultaneously, phytostimulating properties like IAA production, nitrogen fixation, phosphate solubilization, potassium solubilization, siderophore production, ammonia production, HCN and amylase, cellulose, pectinase and catalase were also tested. Bio-inoculation of A. calcoaceticus × P. agglomerans was done in rice crop (HUR 105) with different combination of zinc oxide and zinc sulfate in pot experiment. Findings revealed that root growth (31 ± 1.6), straw yield (32.4 ± 1.7), and grain yield (13 ± 2.0) in the treatment of ZnO (Zn-8.0 kg/ha) with Bio-inoculation was found superior over all treatments. The positive action of Bio-inoculation was also exhibited on growth and yield parameters.

Keywords:

• Klebsiella pneumonia
• Rice yield
• Zinc oxide
• Zinc phosphate
• Zinc solubilization efficiency

Acknowledgments

The authors are grateful to the Institute of environment and sustainable development, Banaras Hindu University, for assistance in molecular analysis and the soil microbiology laboratory of the Department of soil science and agricultural chemistry, Institute of agricultural sciences for the infrastructure supports during experiments. We thank the Department of agronomy for designing treatments for green house experiments and Institute of Sciences for their collaboration in carrying out physiological and morphological studies of bacterial strains.

Conflict of interest

The authors declare that they have no conflicts of interest.