Reducing carbon: phosphorus ratio can enhance microbial phytin mineralization and lessen competition with maize for phosphorus

Abstract

We tested the hypothesis that reducing the carbon (C):Phosphorus (P) ratio in rhizosphere soil would reduce bacterial competition with the plant for P from phytin, which would then increase phytin use efficiency for the plant. A threefactor pot experiment was carried out to study the effect of inoculation with a phytin-mineralizing bacterium, Pseudomonas alcaligenes (PA), on maize P uptake from phytin. Two levels of organic P, two levels of inorganic P, and three different PA inoculation treatments were used. When maize plants were grown in low available P soil with phytin, PA transformed soil P into microbial biomass P, which caused competition for available P with plant and inhibited plant uptake. When 5 mg P kg −1 as KH 2 PO 4 was added, inoculation with PA increased soil acid phosphatase activity which enhanced the mineralization rate of phytin. PA mobilized more P than it immobilized in microbial pool and enhanced plant P uptake. We conclude that the decreased C:P ratio by adding small amount of inorganic P in the rhizosphere could drive phytin mineralization by the bacteria and improve plant P nutrition.

Distribution of phosphatase activity and various bacterial phyla in the rhizosphere of Hordeum vulgare L. depending on P availability

“…Organic P mineralization driven by microbial need for C has recently also been reported to likely be the reason for patterns of phosphatase activity observed in a long term fertilization experiment (Turner and Wright, 2014) and in the rhizosphere of maize (Zhang et al, 2014).…”

Carbon and phosphorus exchange may enable cooperation between an arbuscular mycorrhizal fungus and a phosphate‐solubilizing bacterium

“…Soil available P concentrations can determine the bacterial P contribution to plants by regulating the P mobilizing and immobilizing processes (Stevenson, 1986;Zhang et al, 2014a). This principle formed part of our first hypothesis, which we tested in the microcosm experiment by manipulating available P concentrations.…”

Effect of P- Solubilizing Bacteria on Microbial Biomass P and Phosphatase Activity in Groundnut (Arachis hypogaea L) Rhizosphere

“…Further PSB application enhanced soil phosphatase activity and pots treated with combined application of PSB and SSP favoured phosphatase activity. This may be attributed to higher root and microbial activity (Zhang et al, 2014). The two strains (CTC12 and KHD08) showed more phosphatase activity either in combination or sole compared to other three.…”

“…In addition, the pots treated combinedly with PSB and SSP (P fertilizer) C/P ratio declined. Zhang et al, (2014) reported that addition of inorganic P could decrease the C/P ratio in a low P soil. It is evident from the study that, microorganisms compete with plant roots for the orthophosphate and assimilate the P making it temporarily unavailable for the crop.…”

“…More than 40% of culturable bacteria possess the ability to mobilize insoluble and organic P (Jorquera et al, 2008) and release orthophosphates (H 2 PO 4 − and HPO 4 2− ) that can be absorbed by plant roots (Rodríguez and Fraga, 1999). Mobilization of insoluble organic P by soil bacteria can be regulated by addition of inorganic P fertilizer, which can directly affect the activity of soil microbiota and indirectly enhance the plants ability to take orthophosphates from organically fixed P (Zhang et al, 2014). Anzuay et al (2015) reported that strains of Serratia sp.…”