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Pseudomonas protegens CHA0 does not increase phosphorus uptake from 33P labeled synthetic hydroxyapatite by wheat grown on calcareous soil

Meyer, G.; Maurhofer, M.; Frossard, E.; Gamper, H. A.; Mäder, P.; Mészáros, É.; Schönholzer-Mauclaire, L.; Symanczik, S. and Oberson, A. (2019) Pseudomonas protegens CHA0 does not increase phosphorus uptake from 33P labeled synthetic hydroxyapatite by wheat grown on calcareous soil. Soil Biology and Biochemistry, 131, pp. 217-228.

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Online at: https://www.sciencedirect.com/science/article/abs/pii/S0038071719300239

Summary

Soil microorganisms exuding organic acids have the potential to solubilize inorganic phosphorus (P), which could improve the P availability to plants growing on calcareous soil. The gluconic acid exuding bacteria Pseudomonas protegens CHA0 can solubilize P under glucose rich in vitro conditions, but evidence on the effectiveness in soil is lacking. This discrepancy in P solubilization between in vitro and in vivo is common for many P solubilizing bacteria. Possible causes for this discrepancy are rarely explored in soil using mechanism oriented approaches. Proposed reasons for limitation of bacterial P solubilization in soil are low persistence of the inoculant or low glucose availability in the plant rhizosphere. To test these two hypotheses we investigated the solubilization of 33P labeled synthetic hydroxyapatite (Ca33P) by the gluconic acid producing P. protegens CHA0 wild type and the mutant strain CHA1198 lacking the capacity to produce this acid, in a plant growth experiment with wheat (Triticum aestivum) and an incubation experiment. Neither in the plant growth- nor in the incubation experiment solubilization of Ca33P by strain CHA0 was detected, in spite the inoculated strain persisted in the rhizoplane of wheat and in the sterilized soil amended with glucose. No detected P solubilization in the sterilized inoculated soil suggests that glucose availability was the main limiting factor. The comparison of the results obtained from the two bacterial inoculants suggested that overall microbial activity, i.e., via protonation due to respiration, increased inorganic P mobilization. P solubilizing bacteria should be evaluated using a tracer and an appropriate bacterial control in order to reveal the mechanisms involved in increased plant available P in soil inoculated with P solubilizing bacteria.


EPrint Type:Journal paper
Keywords:Phosphorus, 33P labeling, Phosphorus solubilizing bacteria, Calcareous soil, Pseudomonas protegens CHA0, Department of Soil Sciences, nutrient management and Symbiosis
Subjects: Crop husbandry > Production systems > Cereals, pulses and oilseeds
Soil > Nutrient turnover
Research affiliation: Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Soil Sciences
Switzerland > ETHZ - Agrarwissenschaften
Italy > Scuola Superiore Sant'Anna of Pisa
DOI:10.1016/j.soilbio.2019.01.015
Deposited By: Symanczik, Dr. Sarah
ID Code:36362
Deposited On:21 Aug 2019 08:58
Last Modified:21 Aug 2019 08:58
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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