Abstract

Little is known about the microbial utilization of phosphorus (P) substrates in crop rhizosphere. Homeostasis in plants and soil microorganisms enable cells adapting to limiting inorganic phosphorous (Pi) concentration in soil solutions. Under such conditions, the expressions of thousands of genes change in spatial and temporal scales to coordinate Pi solubilisation, uptake, translocation, recycling and storage. Soil microorganisms influence soil productivity by solubilising and mineralizing soil organic P (Po) through their metabolic processes and make it available to plants. A greenhouse experiment was carried out in the greenhouse to study the utilization of 59 substrates containing P in wheat (Triticum aestivum) and Canola (Brassica napus) rhizosphere. Substrate utilization during the growing season of wheat was determined using BIOLOG’s Phenotype MicroArrays (PM4) system phosphorus/sulphur metabolism. Four replicated treatments were established: soil alone; soil + crop (unfertilized); soil + crop + fertilizer-N; soil + crop + fertilizer-NP. The soil belonged to a Manotick series of the Haplorthods (Melanic Brunisol) Great Group. The most of the substrates were discriminated by phenological stages, treatments and plates incubation times in both crops. In wheat the substrates Adenosine- 3’,5’-cyclic monophosphate and Hypophosphite discriminate for all of the variables and also, several substrates common for those variables as, Thiophosphate, O-Phospho-DTyrosine, D-3-Phospho-Glyceric, Acid Cytidine- 3’- monophosphate, Tripolyphosphate, D-2-Phospho- Glyceric Acid, Dithiophosphate and Trimetaphosphate. In canola crop the substrate Guanosine- 3’,5’-cyclic monophosphate discriminate for all the variables treatments, phenological stages, and plates incubation times, respectively, are common for the most of the variables discriminate D-3-Phospho-Glyceric Acid, Inositol Hexaphosphate, β-Glycerol Phosphate. Both crops together influence significantly on overall data variation, discriminating 21 substrates, the PCA show that the treatment and plate incubation time belong to the component that explain the 34.28% of data variation, in otherwise, the phonological stages belong to the compononent that explain the 16.064% of data variation.