Minjingu phosphate rock solubilization and potential for use of klebsiella variicola-mde4 and klebsiella variicola-mdg1 as biofertilizer for maize production
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Central European Agriculture
Abstract
Limited solubility of the Tanzania’s Minjingu phosphate rock (MPR) in non-acidic soil conditions has held back
its potential for widespread use in agricultural production. This study was designed to isolate, characterize and test
phosphate-solubilizing bacteria for their potential to increase solubility of MPR and enhance maize plant growth
under field conditions. Ten out of 19 isolates showing greatest phosphate solubilization indices on a Pikovskaya agar
medium were further characterized for other plant-growth promoting traits including production of IAA, siderophores
and ammonia. Two of them, namely isolates-MdE4 and MdG1 substantially outperformed other isolates in phosphate
solubilization and production of IAA, ammonia and siderophores. The two isolates molecularly identified as Klebsiella
variicola-MdE4 and K. variicola-MdG1 produced up 701, 699 and 750, 680 µg/ml of soluble phosphate from tricalcium
phosphate and hard Minjungu rock phosphate, respectively. Additionally, Biorock P- a biofertilizer formulation containing
MdE4 and MdG1 co-cultured in a molasses-based modified broth medium retained most of the phosphate solubilizing
potential and other plant-growth promoting traits of MdE4 and MdG1. Co-application of MdE1 and MdG1-containing
“bio-rock P” and inorganic phosphate at 20 kg P/ha resulted in higher maize grain yield than that of positive control (40
kg P/ha) under field conditions. The two isolates- Klebsiella variicola-MdE4 and K. variicola-MdG1 have the potential for
use in a biofertilizer formulation for commercial field applications.
Description
Keywords
Rock phosphate biofertilizer, Biofertilizer formulation, Plant growth promoting bacteria, Inoculant