Kinetics of nitrate and ammonium absorption and accompanying H+fluxes in roots ofLolium perenneL. and N2‐fixingTrifolium repensL.

Høgh‐Jensen, Henning; Wollenweber, Bernd; Schjøerring, Jan K.

doi:10.1046/j.1365-3040.1997.d01-145.x

Cited by 30 publications

(15 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More generally, the higher E/I were observed for the two Fabaceae studied (clover and alfalfa) and the lower ones were observed for the two Poaceae (maize and ryegrass). Studies concerning nitrate and ammonium uptake characteristics have also established that E/I are higher for clover than for ryegrass (Macduff and Jackson 1992;Lainé et al 1993;Høgh-Jensen et al 1997). Together, these results support the view than nitrogen can be transferred from atmospheric nitrogen fixing legumes to companion grasses, through the soil solution (Ta and Faris 1987;Brophy and Heichel 1989;Paynel et al 2001).…”

Section: Discussionmentioning

confidence: 69%

Root amino acid exudation: measurement of high efflux rates of glycine and serine from six different plant species

et al. 2007

View full text Add to dashboard Cite

Amino acid concentration in the rhizosphere results from fluxes between plant roots, soil and microorganisms. In this context, root amino acid exudation process, composed of both efflux and influx, remains unclear. One main issue is to understand the selectivity of amino acid exudation resulting mainly in high proportions of glycine and serine in exudates compared to low proportions inside the root. To reach this point, a quantitative analysis of exudation with dissociated measurements of efflux from influx is needed. We measured efflux and influx by supplying 15 N-labelled glycine or serine for a short time of exposure at ecologically relevant concentrations to plants of white clover (Trifolium repens L.), perennial ryegrass (Lolium perenne L.), maize (Zea mays L.), oilseed rape (Brassica napus L.), tomato (Lycopersicon esculentum Mill.) and alfalfa (Medicago sativa L.). Efflux was estimated by the increase of 14 N content of amino acids in root exudates and influx was estimated by the increase of 15 N content in plant tissue. Glycine efflux exceeded influx for all six species and was much higher in Fabaceae than in Poaceae. Serine efflux exceeded influx in alfalfa, white clover and rape. We conclude that presence of glycine and serine in root bathing solutions results from high glycine and serine efflux rates, observed in all six species studied here. The physiological and ecological significances of these high efflux rates are discussed in the context of N metabolism and plantsoil-microorganisms interactions.

show abstract

Section: Discussionmentioning

confidence: 69%

Root amino acid exudation: measurement of high efflux rates of glycine and serine from six different plant species

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The increased 15 N content in shoots of clover may be explained by a higher translocation rate of N derived from NO 3 to shoots in T. repens compared to L. perenne (Høgh-Jensen et al 1997). Although T. repens took up mainly atmospheric nitrogen with the aid of N 2 fixing bacteria, its shoots received more nitrogen from the litter than the shoots of L. perenne and P. lanceolata.…”

Section: Discussionmentioning

confidence: 98%

Effects of earthworms and organic litter distribution on plant performance and aphid reproduction

et al. 2003

View full text Add to dashboard Cite

Human management practices and large detritivores such as earthworms incorporate plant litter into the soil, thereby forming a heterogeneous soil environment from which plant roots extract nutrients. In a greenhouse experiment we investigated effects of earthworms and spatial distribution of (15)N-labelled grass litter on plants of different functional groups [ Lolium perenne (grass), Plantago lanceolata (forb), Trifolium repens (legume)]. Earthworms enhanced shoot and root growth in L. perenne and P. lanceolata and N uptake from organic litter and soil in all plant species. Litter concentrated in a patch (compared with litter mixed homogeneously into the soil) increased shoot biomass and (15)N uptake from the litter in L. perenne and enhanced root proliferation in P. lanceolata when earthworms were present. Growth of clover (T. repens) was rather independent of the presence of earthworms and organic litter distribution: nevertheless, clover took up more nitrogen in the presence of earthworms and exploited more (15)N from the added litter than the other plant species. The magnitude of the effects of earthworms and organic litter distribution differed between the plant species, indicating different responses of plants with contrasting root morphology. Aphid (Myzus persicae) reproduction was reduced on P. lanceolata in the presence of earthworms. We suggest that earthworm activity may indirectly alter plant chemistry and hence defence mechanisms against herbivores.

show abstract

“…Plants take up NH þ 4 and NO À 3 following a Michaelis-Menten equation (Høgh-Jensen et al 1997;Adamowicz and Le Bot 1999). Exudation of organic molecules from the root exudation zone is modelled as the result of a passive leakage of organic matter using Fick's law.…”

Section: Root Modelmentioning

confidence: 99%

“…Williams and Yanai (1996) and Høgh-Jensen et al (1997) Root elongation gP 3.3 · 10 -5 cm -1 AE s -1 Farrar and Jones (2000) Length between apex and exudation zone B E 0 Length of exudation zone L E 8.5 cm Length between apex and absorption zone B A 0 Length of absorption zone L A ¥ Ammonium maximal absorption capacity I max P (NH þ 4 ) 1 · 10 -9 mmol Á cm À2 Á s À1 Høgh- Jensen et al (1997) Half saturation constant for ammonium uptake K M P (NH þ 4 ) 1 · 10 -4 mmol Á cm À3 Høgh- Jensen et al (1997) Nitrate maximal absorption capacity I max P (NO À 3 ) 1 · 10 -9 mmol Á cm À2 Á s À1 Høgh- Jensen et al (1997) Half saturation constant for nitrate uptake K M P (NO À 3 ) 1 · 10 -4 mmol Á cm À3 Høgh- Jensen et al (1997) Membrane permeability of organic molecules PermP (N i org ) (1 · 10 -7 , 0, 0) cm À2 Á s À1 Estimated from Nielsen et al (1994) Williams and Yanai (1996) Organic molecules concentration ½N i org (5 · 10 -8 , 1 · 10 -6 , 1 · 10 -5 ) mmol -1 AE cm -3 Organic molecules effective diffusion Multiple values in parenthesis correspond to coefficients for classes of organic matter…”

Section: Appendix B: Plant and Soil Parametersmentioning

confidence: 99%

See 1 more Smart Citation

Soil microbial loop and nutrient uptake by plants: a test using a coupled C:N model of plant–microbial interactions

2006

View full text Add to dashboard Cite

We have developed a spatially explicit model of plant root and soil bacteria interactions in the rhizosphere in order to formalise and study the microbial loop hypothesis that postulates that plants can stimulate the release of mineral N from the soil organic matter by providing low molecular weight C molecules to C-limited microorganisms able to liberate into the soil enzymes that degrade the organic matter. The model is based on a mechanistic description of diffusion of solutes in the soil, nutrient uptake by plants, bacterial activity and bacterial predation. Modelled soil bacterial populations grow, mediate transformations among several forms of nitrogen (mineral and organic) and compete for nitrogen with plants. Our objectives were to see if we could simulate the stimulation of turnover of the microbial loop by exudates and to study the effects of diffusion of C and N in the rhizosphere on these different processes. The model qualitatively mimics most of the characteristics of the microbial loop hypothesis. In particular, (1) plant exudates increase the growth of bacteria in the soil and (2) increase the degradation of soil organic matter and N mineralisation. (3) The increased bacterial biomass induces an increase in predator biomass and, as a result, (4) plant mineral N uptake is increased threefold compared with scenarios without exudation. However, the temporal dynamics simulated by the model are much slower than observed dynamics (the increase in uptake appears after a few months). Taking into consideration the diffusion of C and N containing molecules in soil has large effects on the spatial structure of the bacterial and predator biomass. However, the average biomass of bacteria and predators, N mineralisation and plant N uptake were not affected by these properties. The model provides a quantitative and mechanistic explanation of how plants could beneﬁt from liberating low molecular organic matter and the subsequent stimulation of the microbial loop and increases N mineralisation

show abstract

Kinetics of nitrate and ammonium absorption and accompanying H⁺fluxes in roots ofLolium perenneL. and N₂‐fixingTrifolium repensL.

Cited by 30 publications

References 42 publications

Root amino acid exudation: measurement of high efflux rates of glycine and serine from six different plant species

Root amino acid exudation: measurement of high efflux rates of glycine and serine from six different plant species

Effects of earthworms and organic litter distribution on plant performance and aphid reproduction

Soil microbial loop and nutrient uptake by plants: a test using a coupled C:N model of plant–microbial interactions

Contact Info

Product

Resources

About