Role of root derived organic acids in the mobilization of nutrients from the rhizosphere

Abstract

The role of organic acids in the mobilization of plant nutrients from the rhizosphere was assessed in seven contrasting soil types. The results indicated that malate was poor at mobilizing micronutrients from all the test soils, whilst citrate was capable of mobilizing significant quantities. Citrate was also capable of mobilizing P from one soil which possessed a large Ca-P fraction. This mobilization of P was due to both the complexing action of the citrate anion and due to the dissolution properties of the protons released from citric acid upon equilibrium with the soil solution. The reaction of citrate with cations was found to be near instantaneous with significant absorption to the solid phase in some soils at low concentrations. Soil decomposition studies indicated that citrate was rapidly broken down in organic soils but was more resistant to degradation in subsoil horizons. It was concluded that organic acids can be expected to be of little consequence in nutrient mobilization from high pH soils, whilst in acid soils they may be involved both in a more general mechanism for micronutrient uptake or as a potential A1 detoxification mechanism.Abbreviations: Citric acid and H-citrate indicates C6H807, whilst Na-citrate indicates C6HsO7Na3.

Genotypic variation in phosphorus acquisition from sparingly soluble P sources is related to root morphology and root exudates in Brassica napus

“…However, it has been reported that there is wide genotypic variation in the utilization of sparingly soluble P among plant species and genotypes [26][27][28]. The results obtained in the present study show that genotype 102 was more P-efficient because it was able to produce up to 59% and 27% of its maximum dry weight when supplied with Al-P and Fe-P, respectively, whereas genotype 105 produced only 49% and 25%, respectively, of its maximum dry weight under the same conditions (Figure 1).…”

Microbial Community Behaviour in The Rhizosphere of Kilemo (Litsea cubeba L. Pers) After Pruning

“…Therefore, for exudates efficiency, roots have to limit the size of rhizosphere community. Jones and Darrah (1994) explained that plants have several mechanisms in reducing soil community magnitude in their root zones. Primarily, plants decline their root exudates productivity.…”

Heavy Metals in Vineyards and Orchard Soils

“…At the same time organic acids may derive from organic matter (root or shoot residues) decomposition, promoted by microorganisms (PII et al, 2015). The dissolved organic compounds in the soil solution have a high affinity with heavy metals, reducing the potential toxicity for plants (JONES;DARRAH, 1994;MEIER et al, 2012;PÉREZ-ESTEBAN et al, 2014).…”