Title: Development of an inoculant of phosphate rock-solubilizing bacteria to improve maize growth and nutrition
Abstract: Phosphorus (P) is one of the major elements for plant growth; however, plant-available phosphorus is limited because it reacts with cations present in soil, forming low solubility phosphates. Therefore soluble P chemical fertilizers are used, but cost and concerns about environmental pollution through industrial production make the direct use of phosphate rocks (PRs) a more sustainable alternative for agriculture. The aim of this work was to isolate phosphate rock-solubilizing bacteria (PRSB) from maize mycorrhizosphere, capable of mobilizing P from PR and from low solubility P sources for sustainable organic maize production and to determine the solubilizing capacity of the isolated bacteria in the presence of PRs with different reactivities. Out of 118 isolates from maize cultivated in Quebec, eight belonging to Asaia lannaensis, Rahnella aquatilis, Pantoea agglomerans and Pseudomonas sp. were found to be the best PRSB. On solid media all strains mobilized P from Ca3(PO4)2, hydroxyapatite and PRs. A. lannaensis Vb1 was the only PRSB showing visible solubilization of AlPO4 and FePO4. In liquid media, PRs were solubilized by all the PRSB by producing Dgluconic acid and 2-ketogluconic acid and by lowering the pH. Depending on the reactivity of the PR used, Gafsa (the most reactive) allowed significantly higher P solubilization P(<0.001), followed by Tilemsi and finally Morocco (less reactive). The selected isolated improved the PR-solubilization by the addition of 12mM of EDTA in the liquid medium when Morocco PR was used as source of P. The best PRSB from each group (A. lannaensis Vb1, Pseudomonas Vr14, R. aquatilis Sr24 and P.agglomerans Vr25) were selected based on high PR solubilization, and IAA and siderophore production. These four isolates presented different biofilm formation and motility capacities. The selected isolates significantly increased shoot and root dry matter yields of two week old maize seedlings. The selected PRSB presented attributes suggesting that they can be used in the development of inoculants for organic maize production.
Publication Year: 2014
Publication Date: 2014-01-01
Language: en
Type: article
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Cited By Count: 3
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