Role of Humic Substances in the Rhizosphere

Pinton, Roberto; Cesco, Stefano; Varanini, Zeno

doi:10.1002/9780470494950.ch9

Cited by 13 publications

(10 citation statements)

References 111 publications

(108 reference statements)

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“…Although studies have shown the positive effect of HAs on the uptake of many nutrients (Vaughan & Malcolm, ; Chen & Aviad, , Nardi et al , ; Pinton et al , ), reports that investigate the LATS and HATS of NRTs and analyse the mechanisms involved in this process are rare. Therefore, the aim of this study was to evaluate the changes in root morphology of Piauí rice plants promoted by HAs action.…”

Section: Introductionmentioning

confidence: 99%

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

et al. 2016

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Humic acids (HAs) have a major effect on nutrient uptake, metabolism, growth and development in plants. Here, we evaluated the effect of HA pretreatment applied with a nutrient solution on the uptake kinetics of nitrate nitrogen (N-NO 3 − ) and the metabolism of nitrogen (N) in rice under conditions of high and low NO 3 − supply. In addition, the kinetic parameters of NO 3 − uptake, N metabolites, and nitrate transporters (NRTs) and the plasma membrane (PM) H + -ATPase gene expression were examined. The plants were grown in a growth chamber with modified Hoagland and Arnon solution until 21 days after germination (DAG), and they were then transferred to a solution without N for 48 h and then to another solution without N and with and without the addition of HAs for another 48 h. After this period of N deprivation, the plants received new nutrient solutions containing 0.2 and 2.0 mM N-NO 3 − . Treatment of rice plants with HA promoted the induction of the genes OsNRT2.1-2.2/OsNAR2.1 and some isoforms PM H + -ATPase in roots. The application of HAs differentially modified the parameters of the uptake kinetics of NO 3 − under both concentrations. When grown with 0.2 mM NO 3 − , the plants pretreated with HA had lower K m and C min values as well as a higher V max /K m ratio. When grown with 2 mM NO 3 − , the plants pretreated with HA had a higher V max value, a greater root and shoot mass, and a lower root/shoot ratio. The N fractions were also altered by pretreatment with HA, and a greater accumulation of NO 3 − and N-amino was observed in the roots and shoots, respectively, of plants pretreated with HA. The results suggest that pretreatment with HA modifies root morphology and gene expression of PM H + -ATPases and NO 3 − transporters, resulting in a greater efficiency of NO 3 − acquisition by high-and low-affinity systems.

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Section: Introductionmentioning

confidence: 99%

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

et al. 2016

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“…The functions of dissolved organic matter (DOM) in soils, specifically humic substances (DOM-HSs), are well established 1 2 3 4 . Several studies show that DOM-HSs regulate metabolic processes related to plant growth, especially the emission and growth of the root system 5 6 7 8 9 10 11 12 .…”

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confidence: 99%

Structure-Property-Function Relationship in Humic Substances to Explain the Biological Activity in Plants

García

Souza

Pereira

et al. 2016

Sci Rep

136

103

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Knowledge of the structure-property-function relationship of humic substances (HSs) is key for understanding their role in soil. Despite progress, studies on this topic are still under discussion. We analyzed 37 humic fractions with respect to their isotopic composition, structural characteristics, and properties responsible for stimulating plant root parameters. We showed that regardless of the source of origin of the carbon (C3 or C4), soil-extracted HSs and humic acids (HAs) are structurally similar to each other. The more labile and functionalized HS fraction is responsible for root emission, whereas the more recalcitrant and less functionalized HA fraction is related to root growth. Labile structures promote root stimulation at lower concentrations, while recalcitrant structures require higher concentrations to promote a similar stimulus. These findings show that lability and recalcitrance, which are derived properties of humic fractions, are related to the type and intensity of their bioactivity. In summary, the comparison of humic fractions allowed a better understanding of the relationship between the source of origin of plant carbon and the structure, properties, and type and intensity of the bioactivity of HSs in plants. In this study, scientific concepts are unified and the basis for the agronomic use of HSs is established.

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“…Higher contents of carboxylic, phenolic, hydroxylic, and other functional groups in HA and FA function as nutrients chelator [ 79 – 81 ]. Moreover, HA and FA had higher total acidity (CEC) that enables nutrients retention at the exchange site (functional groups) and their timely release for plant uptake.…”

Section: Resultsmentioning

confidence: 99%

Compost and Crude Humic Substances Produced from Selected Wastes and Their Effects on Zea mays L. Nutrient Uptake and Growth

Palanivell

Kasim

Ahmed

et al. 2013

The Scientific World Journal

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Production of agriculture and timber commodities leads generation of enormous quantity of wastes. Improper disposal of these agroindustrial wastes pollutes the environment. This problem could be reduced by adding value to them. Therefore, a study was carried out to analyse and compare the nutrients content of RS, RH, SD, and EFB of composts and crude humic substances; furthermore, their effect on growth, dry matter production, and nutrient uptake for Zea mays L., and selected soil chemical properties were evaluated. Standard procedures were used to analyze humic acids (HA), crude fulvic acids (CFA), crude humin (CH), soil, dry matter production and nutrient uptake. Sawdust and RS compost matured at 42 and 47 days, respectively, while RH and EFB composts were less matured at 49th day of composting. Rice straw compost had higher ash, N, P, CEC, HA, K, and Fe contents with lower organic matter, total organic carbon, and C/N and C/P ratios. The HA of sawdust compost showed higher carbon, carboxylic, K, and Ca contents compared to those of RS, RH, and EFB. Crude FA of RS compost showed highest pH, total K, Ca, Mg, and Na contents. Crude humin from RS compost had higher contents of ash, N, P, and CEC. Rice straw was superior in compost, CFA, and CH, while sawdust compost was superior in HA. Application of sawdust compost significantly increased maize plants' diameter, height, dry matter production, N, P, and cations uptake. It also reduced N, P, and K based chemical fertilizer use by 90%. Application of CH and the composts evaluated in this study could be used as an alternative for chemical fertilizers in maize cultivation.

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Role of Humic Substances in the Rhizosphere

Cited by 13 publications

References 111 publications

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

Structure-Property-Function Relationship in Humic Substances to Explain the Biological Activity in Plants

Compost and Crude Humic Substances Produced from Selected Wastes and Their Effects on Zea mays L. Nutrient Uptake and Growth

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Role of Humic Substances in the Rhizosphere

Cited by 13 publications

References 111 publications

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H+-ATPases and nitrate transporters in rice

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H+-ATPases and nitrate transporters in rice

Structure-Property-Function Relationship in Humic Substances to Explain the Biological Activity in Plants

Compost and Crude Humic Substances Produced from Selected Wastes and Their Effects on Zea mays L. Nutrient Uptake and Growth

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Product

Resources

About

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice

Humic acid differentially improves nitrate kinetics under low- and high-affinity systems and alters the expression of plasma membrane H⁺-ATPases and nitrate transporters in rice