Qualitative and quantitative analysis of water-soluble root exudates in relation to plant species and development

Gransee, Andreas; Wittenmayer, Lutz

doi:10.1002/1522-2624(200008)163:4<381::aid-jpln381>3.0.co;2-7

Cited by 181 publications

(93 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Plant phenology may influence root biomass as well as rhizodeposition, mainly through root growth dynamics and differences in the quantity of rhizodeposits (Vancura 1964;Klein et al 1988; Van der Krift et al 2001;Jones et al 2004). At young age, plants translocate more carbon to the roots, whereas older plants preferably retain newly assimilated C in the shoots (Keith et al 1986;Gregory and Atwell 1991;Palta and Gregory 1997;Gransee and Wittenmayer 2000) thus, leading to decreased C inputs into the soil due to a decreased assimilates allocation to the roots (reviewed by Nguyen 2003). Aging of plants decreases the exudation intensity, however, if this decrease is slower than the root growth total rhizodeposition will increase (Kuzyakov 2002).…”

Section: Factors Affecting Root Biomass And/or Rhizodepositionmentioning

confidence: 99%

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

et al. 2012

View full text Add to dashboard Cite

Background and aims Rhizodeposition of plants is the most uncertain component of the carbon (C) cycle. By existing approaches the amount of rhizodeposition can only roughly be estimated since its persistence in soil is very short compared to other organic C pools. We suggest an approach to quantify rhizodeposition at the field scale by assuming a constant ratio between rhizodeposited-C to root-C. Methods Maize plants were pulse-labeled with 14 CO 2 under controlled conditions and the soil 14 CO 2 efflux was separated into root and rhizomicrobial respiration. The latter and the 14 C activity remaining in the soil corresponded to total rhizodeposition. By relating rhizodeposited-14 C to root-14 C a rhizodeposition-toroot ratio of 0.56 was calculated. This ratio was applied to the root biomass C measured in the field to estimate rhizodeposition under field conditions. Results Maize allocated 298 kg C ha −1 as root-C and 166 kg C ha −1 as rhizodeposited-C belowground, 50 % of which were recovered in the upper 10 cm. The fate of rhizodeposits was estimated based on the 14 C data, which showed that 62 % of total rhizodeposition was mineralized within 16 days, 7 % and 0.3 % was incorporated into microbial biomass and DOC, respectively, and 31 % was recovered in the soil.Conclusions We conclude that the present approach allows for an improved estimation of total rhizodeposition, since it accounts not only for the fraction of rhizodeposits remaining in soil, but also for that decomposed by microorganisms and released from the soil as CO 2 .

show abstract

Section: Factors Affecting Root Biomass And/or Rhizodepositionmentioning

confidence: 99%

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

et al. 2012

View full text Add to dashboard Cite

show abstract

“…If labile components are present at depth, it is most likely that they are either derived from the surface, possibly transported as dissolved organic carbon, or derived from root exudates, which contain large amounts of low molecular weight compounds like carbohydrates, carboxylic acids and amino acids (e.g. Gransee and Wittenmayer, 2000). Pancost and Sinninghe Damsté (2003) similarly suggested a heterotrophic life style for the branched-GDGT synthesising organism in the Bargerveen peat bog based on similar small differences between the isotopic compositions of 13,16-dimethyloctacosane and TOC.…”

Section: The Metabolism Of Branched Gdgt Producersmentioning

confidence: 99%

Carbon isotopic composition of branched tetraether membrane lipids in soils suggest a rapid turnover and a heterotrophic life style of their source organism(s)

et al. 2010

View full text Add to dashboard Cite

Abstract. Branched Glycerol Dialkyl Glycerol Tetraethers (GDGTs) are membrane spanning lipids synthesised by as yet unknown bacteria that thrive in soils and peat. In order to obtain more information on their ecological niche, the stable carbon isotopic composition of branched GDGT-derived alkanes, obtained upon ether bond cleavage, has been determined in a peat and various soils, i.e. forest, grassland and cropland, covered by various vegetation types, i.e., C 3 -vs. C 4 -plant type. These δ 13 C values are compared with those of bulk organic matter and higher plant derived nalkanes from the same soils. With average δ 13 C values of −28‰, branched GDGTs in C 3 soils are only slightly depleted (ca. 1‰) relative to bulk organic carbon and on average 8.5‰ enriched relative to plant wax-derived long-chain n-alkanes (nC 29 − nC 33 ). In an Australian soil dominantly covered with C 4 type vegetation, the branched GDGTs have a δ 13 C value of −18‰, clearly higher than observed in soils with C 3 type vegetation. As with C 3 vegetated soils, branched GDGT δ 13 C values are slightly depleted (1‰) relative to bulk organic carbon and enriched (ca. 5‰) relative to n-alkanes in this soil. The δ 13 C values of branched GDGT lipids being similar to bulk organic carbon and theirCorrespondence to: J. W. H. Weijers (j.weijers@geo.uu.nl) co-variation with those of bulk organic carbon and plant waxes, suggest a heterotrophic life style and assimilation of relatively heavy and likely labile substrates for the as yet unknown soil bacteria that synthesise the branched GDGT lipids. However, a chemoautotrophic lifestyle, i.e. consuming respired CO 2 , could not be fully excluded based on these data alone. Based on a natural labelling experiment of a C 3 /C 4 crop change introduced on one of the soils 23 years before sampling and based on a free-air CO 2 enrichment experiment with labelled CO 2 on another soil, a turnover time of ca. 18 years has been estimated for branched GDGTs in these arable soils.

show abstract

“…Gransee and Wittenmayer [30] proposed a method of growing plants in quartz sand filled with NS and dipping the roots into distilled water to gain exudates. This method has been used with 14 C labelling, but it has not been tested with measuring of δ 13 C values.…”

Section: Discussionmentioning

confidence: 99%

“…• C. Immediately after sampling of the NSs, Micropur (Katadyn, Switzerland) containing Ag + ions was added to the flask containing exuded organic substances to suppress their microbial decomposition before analysis [29,30].…”

Section: Labelling and Samplingmentioning

confidence: 99%

Below-ground partitioning (¹⁴C) and isotopic fractionation (δ¹³C) of carbon recently assimilated by maize

Werth

Kuzyakov

2005

Isotopes in Environmental and Health Studies

View full text Add to dashboard Cite

Partitioning of carbon recently assimilated by maize between shoots, roots, exudates, and CO 2 from root respiration depending on three different levels of nutrient supply (full nutrient solution (NS), 10 times diluted NS, or deionised water) was estimated by 14 C pulse labelling. A 13 C fractionation in these compartments was investigated in relation to the nutrient supply. With decreasing nutrient supply, 14 C allocation to the shoots and to the roots decreased from 76 % to 69 % and increased from 8 % to 13 % of 14 C recovery, respectively. Average percentage of 14 C in exudates and root-respired CO 2 was 0.5 % and 16 % of 14 C recovery, respectively. The concentration of the NS was not crucial for the amount of recently assimilated C recovered in exudates and CO 2 , but for the amounts in shoots and roots. For all three nutrient levels, roots were enriched in 13 C when compared with shoots and 13 C fractionation increased with decreasing nutrient supply up to 0.7 ‰. Further 13 C discrimination by exudation led to more 13 C in exudates when compared with the roots of full nutrient supply and less 13 C in exudates when compared with the roots grown in diluted NS and in deionised water. There were only small differences of <1.0 ‰ in δ 13 C values between roots and CO 2 from root respiration. A 13 C fractionation of recently assimilated C occurred between roots and exudates but was negligible for the CO 2 respired by roots.

show abstract

Qualitative and quantitative analysis of water-soluble root exudates in relation to plant species and development

Cited by 181 publications

References 0 publications

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

Carbon isotopic composition of branched tetraether membrane lipids in soils suggest a rapid turnover and a heterotrophic life style of their source organism(s)

Below-ground partitioning (¹⁴C) and isotopic fractionation (δ¹³C) of carbon recently assimilated by maize

Contact Info

Product

Resources

About

Qualitative and quantitative analysis of water-soluble root exudates in relation to plant species and development

Cited by 181 publications

References 0 publications

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

Estimation of rhizodeposition at field scale: upscaling of a 14C labeling study

Carbon isotopic composition of branched tetraether membrane lipids in soils suggest a rapid turnover and a heterotrophic life style of their source organism(s)

Below-ground partitioning (14C) and isotopic fractionation (δ13C) of carbon recently assimilated by maize

Contact Info

Product

Resources

About

Below-ground partitioning (¹⁴C) and isotopic fractionation (δ¹³C) of carbon recently assimilated by maize