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Richardson, Alan; Hadobas, P. A.; Hayes, J. F.; O'Hara, Christopher; Simpson, Richard J.

doi:10.1023/a:1004871704173

Cited by 180 publications

(43 citation statements)

References 23 publications

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“…In addition to this, we propose that P is not accumulated in the roots, but rapidly mobilised within the plant and utilised in new plant tissue. Overall, values of [P] in roots of E. coccineum were lower than those found in other species bearing similar root structure growing in hydroponics (Keerthisinghe et al 1998;Shane et al 2004b;Shane and Lambers 2006;Shane et al 2004c), but similar values of [P] have been found in other roots of plants growing in soil Ratnayake et al 1978;Richardson et al 2001).…”

Section: Total P and Mn Concentrations In Roots Of E Coccineumsupporting

confidence: 54%

Cluster roots of Embothrium coccineum (Proteaceae) affect enzyme activities and phosphorus lability in rhizosphere soil

et al. 2015

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Background and aim Cluster roots have a profound effect on their rhizosphere. Our aim was to determine the effect of cluster roots of Embothrium coccineum, growing under natural conditions, on soil enzyme activities and phosphorus (P) lability in its rhizosphere. Methods We determined enzyme activities: acid phosphatase (P-ase), dehydrogenase and β-glucosidase, and the rate of hydrolysis of fluorescein diacetate (FDA), as well as P fractions in the cluster root rhizosphere at different cluster-root developmental stages (juvenile, mature, semi-senescent, senescent), in the non-cluster root rhizosphere, and in bulk soil. In addition, the concentrations of total P and manganese Mn in roots was measured. ResultsThe rhizosphere of senescing cluster roots presented the highest P-ase, β-glucosidase and dehydrogenase activities, and fastest rate of FDA hydrolysis, being 2.6-, 4.6-, 3.3-and 25.8-fold greater, respectively, than those in the rhizosphere of mature cluster roots. The P fractionation showed that the inorganic P (Pi) fraction was 15 % greater in the rhizosphere of mature cluster roots than in that of other stages. Mature cluster roots showed the highest total [P], suggesting the fastest P uptake. Conclusion Cluster roots of E. coccineum modified their rhizosphere depending on their developmental stage, presenting lower soil enzyme activities at the mature stage than at other development stages. In addition, mature cluster roots increased the Pi fraction in their rhizosphere, allowing the highest total root [P] at this developmental stage.

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Section: Total P and Mn Concentrations In Roots Of E Coccineumsupporting

confidence: 54%

Cluster roots of Embothrium coccineum (Proteaceae) affect enzyme activities and phosphorus lability in rhizosphere soil

et al. 2015

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“…Plant roots and soil microorganisms are important in mineralisation of organic P, with phosphatases and phytases of bacterial (Richardson and Hadobas 1997;Richardson et al 2001b;Tye et al 2002), fungal (Richardson et al 2001a;Ullah et al 2002), and plant (Lung et al 2005;Xiao et al 2005) origin reported to hydrolyse significant amounts of soluble organic P substrates and release free phosphate anions for root uptake (Fig. 1).…”

Section: Microbially Mediated Phosphorus Availability In Soilsmentioning

confidence: 99%

“…1). Research has indicated elevated phosphatase activity in the rhizosphere compared with the bulk soil (Bowen and Rovira 1999;Richardson et al 2001b;Jakobsen et al 2005); however, the relative importance of microbial-or root-derived extracellular enzyme activities remains to be determined. Phosphatase expression is potentially an important mechanism by which soil-borne microbes and plant roots can use the pool of soil organic P and increase plant-available P in the rhizosphere (Richardson 2001;Jakobsen et al 2005).…”

Section: Microbially Mediated Phosphorus Availability In Soilsmentioning

confidence: 99%

Potential to improve root access to phosphorus: the role of non-symbiotic microbial inoculants in the rhizosphere

2009

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Phosphate anions in soil solution are extremely reactive and may be rapidly immobilised in the soil through precipitation and adsorption reactions, resulting in sparingly soluble forms of phosphorus (P) that are essentially unavailable to plants. This low P-fertiliser efficiency is often offset through high application rates, which are economically and environmentally unsustainable and not an available option for organic producers. Microorganisms play a fundamental role in the biogeochemical cycling of inorganic and organic P in the rhizosphere and detritusphere. Free-living rhizosphere microbes can directly increase the availability of phosphate to plant roots via mechanisms associated with solubilisation and mineralisation of P from inorganic and organic forms of total soil P. These include releasing organic anions, H + ions, phosphatases, and cation chelating compounds into the rhizosphere. Many soil-borne microbes also increase P availability indirectly by producing phytohormones that increase root density and function. There is increasing interest worldwide in the use of rhizosphere microorganisms as inoculants to increase P availability for agricultural production. Recent research has focussed on developing actively sporulating Penicillium fungi known to express mechanisms to enhance P mobilisation and therefore, considered to be a key component of the mycoflora involved in P cycling in soils. Penicillium species do not exhibit specific plant or soil associations and have a broad agro-ecological range, indicating their potential to be developed as inoculants for a range of plant production systems. Successful adoption of microbial inoculants requires a thorough understanding of their rhizosphere ecology, genetic stability, and the mechanisms associated with enhancing P availability in soils and plant-growth promotion. This will provide a better understanding of which inoculants to use under particular agro-ecological conditions for increased efficacy and consistent performance.

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“…Soil microorganisms mineralize organic phosphorus (such as phytate) into inorganic phosphates [3,4,5]. However, high concentrations of Fe, Al, and Ca (described as ‘mineral concentration’ in this paper) could limit the availability of phosphorus, even at high level microbial biomass.…”

Section: Introductionmentioning

confidence: 99%

“…Although the effects of microorganisms, pH, and minerals (such as Fe, Al, and Ca) on phosphorus availability have been independently investigated [3,4,5,6,7,8], the total effects of these factors on phosphorus circulation activity in the soil are still unclear. In this study, the relationship among phosphorus circulation activity, bacterial biomass, pH, and mineral concentration (Fe, Al, and Ca) were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Relationship among Phosphorus Circulation Activity, Bacterial Biomass, pH, and Mineral Concentration in Agricultural Soil

et al. 2017

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Improvement of phosphorus circulation in the soil is necessary to enhance phosphorus availability to plants. Phosphorus circulation activity is an index of soil’s ability to supply soluble phosphorus from organic phosphorus in the soil solution. To understand the relationship among phosphorus circulation activity; bacterial biomass; pH; and Fe, Al, and Ca concentrations (described as mineral concentration in this paper) in agricultural soil, 232 soil samples from various agricultural fields were collected and analyzed. A weak relationship between phosphorus circulation activity and bacterial biomass was observed in all soil samples (R2 = 0.25), and this relationship became significantly stronger at near-neutral pH (6.0–7.3; R2 = 0.67). No relationship between phosphorus circulation activity and bacterial biomass was observed at acidic (pH < 6.0) or alkaline (pH > 7.3) pH. A negative correlation between Fe and Al concentrations and phosphorus circulation activity was observed at acidic pH (R2 = 0.72 and 0.73, respectively), as well as for Ca at alkaline pH (R2 = 0.64). Therefore, bacterial biomass, pH, and mineral concentration should be considered together for activation of phosphorus circulation activity in the soil. A relationship model was proposed based on the effects of bacterial biomass and mineral concentration on phosphorus circulation activity. The suitable conditions of bacterial biomass, pH, and mineral concentration for phosphorus circulation activity could be estimated from the relationship model.

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Untitled

Cited by 180 publications

References 23 publications

Cluster roots of Embothrium coccineum (Proteaceae) affect enzyme activities and phosphorus lability in rhizosphere soil

Cluster roots of Embothrium coccineum (Proteaceae) affect enzyme activities and phosphorus lability in rhizosphere soil

Potential to improve root access to phosphorus: the role of non-symbiotic microbial inoculants in the rhizosphere

Relationship among Phosphorus Circulation Activity, Bacterial Biomass, pH, and Mineral Concentration in Agricultural Soil

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