Characterisation and microbial utilisation of exudate material from the rhizosphere of Lolium perenne grown under CO2 enrichment

Hodge, Angela; Paterson, Eric; Grayston, Susan J.; Campbell, Colin D.; Ord, B. G.; Killham, K.

doi:10.1016/s0038-0717(97)00269-1

Cited by 88 publications

(51 citation statements)

References 56 publications

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“…An increase in culturable bacteria and a simultaneous decrease in total bacterial cells (with a dominance of oligotrophic, "non-culturable" K-strategists) under elevated CO 2 was observed by Hodge et al (1998) in the rhizosphere of L. perenne and by Insam et al (1999) in artificial tropical systems. The number of culturable bacteria was significantly higher in L. perenne rhizosphere after 2 years under 600 ppm CO 2 as compared to current conditions, whereas no changes were observed in the bulk soil (Marilley et al 1999).…”

Section: Effects Of Elevated Co 2 On the Dynamics Of Rhizosphere Micrmentioning

confidence: 93%

“…Elhottova et al (1997) showed changes in the composition of bacterial nutritional groups at elevated CO 2 . Hodge et al (1998) linked the faster utilization of Biolog C-sources by bacteria isolated from the rhizosphere soil of perennial grasses grown under elevated CO 2 to a higher number of culturable bacteria. However, Insam et al (1999) did not observe changes in community level physiological profiles with Biolog plates nor in PLFA profiles of isolates from an artificial tropical plant-soil ecosystem at elevated atmospheric CO 2 levels.…”

Section: Effects Of Elevated Co 2 On the Dynamics Of Rhizosphere Micrmentioning

confidence: 99%

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Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

2008

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General concern about climate change has led to growing interest in the responses of terrestrial ecosystems to elevated concentrations of CO 2 in the atmosphere. Experimentation during the last two to three decades using a large variety of approaches has provided sufficient information to conclude that enrichment of atmospheric CO 2 may have severe impact on terrestrial ecosystems. This impact is mainly due to the changes in the organic C dynamics as a result of the effects of elevated CO 2 on the primary source of organic C in soil, i.e., plant photosynthesis. As the majority of life in soil is heterotrophic and dependent on the input of plant-derived organic C, the activity and functioning of soil organisms will greatly be influenced by changes in the atmospheric CO 2 concentration. In this review, we examine the current state of the art with respect to effects of elevated atmospheric CO 2 on soil microbial communities, with a focus on microbial community structure. On the basis of the existing information, we conclude that the main effects of elevated atmospheric CO 2 on soil microbiota occur via plant metabolism and root secretion, especially in C3 plants, thereby directly affecting the mycorrhizal, bacterial, and fungal communities in the close vicinity of the root. There is little or no direct effect on the microbial community of the bulk soil. In particular, we have explored the impact of these changes on rhizosphere interactions and ecosystem processes, including food web interactions.

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Section: Effects Of Elevated Co 2 On the Dynamics Of Rhizosphere Micrmentioning

confidence: 93%

Section: Effects Of Elevated Co 2 On the Dynamics Of Rhizosphere Micrmentioning

confidence: 99%

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

2008

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“…Although root biomass is often increased when plants are grown in elevated [CO # ], there is little evidence to suggest upregulation in root physiology (Jackson & Reynolds, 1996). In fact, root specific activity is often downregulated in crop plants grown in elevated [CO # ], despite the fact that roots often have greater quantities of nonstructural carbohydrates present in root tissue (Jongen et al, 1995 ;BassiriRad et al, 1996) and the fact that nutrients are often supplied at nonlimiting levels (Newbery et al, 1995 ;Hodge et al, 1998). Lower specific rates of root activity are reflected by greater C : nutrient ratios in conjunction with decreased tissue concentrations of nutrients including N (Israel et al, 1990 ;Hodge et al, 1998) and potassium (K ; Newbery et al, 1995).…”

Section: Nutrient Uptakementioning

confidence: 99%

“…In fact, root specific activity is often downregulated in crop plants grown in elevated [CO # ], despite the fact that roots often have greater quantities of nonstructural carbohydrates present in root tissue (Jongen et al, 1995 ;BassiriRad et al, 1996) and the fact that nutrients are often supplied at nonlimiting levels (Newbery et al, 1995 ;Hodge et al, 1998). Lower specific rates of root activity are reflected by greater C : nutrient ratios in conjunction with decreased tissue concentrations of nutrients including N (Israel et al, 1990 ;Hodge et al, 1998) and potassium (K ; Newbery et al, 1995). Decreases in nutrient uptake efficiency might result from the production of more inefficient root architectures (Fitter, 1996), from limitations imposed by anatomical characteristics (Bunce, 1996 ;Huxman et al, 1999), from reduced mass flow of water through the soil-plant-air continuum (Lambers et al, 1996), from inefficient or unbalanced plant C and N relations, or from a reduction in the competitive ability of roots (in comparison with microbes and the roots of competing plants) to acquire nutrients (Dı!…”

Section: Nutrient Uptakementioning

confidence: 99%

Spatial and temporal deployment of crop roots in CO₂‐enriched environments

2000

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 Growth of crops in CO# -enriched atmospheres typically results in significant changes in root growth and development. Increased root carbohydrates stimulate root growth either directly (functioning as substrates) or indirectly (functioning as signal molecules) by enhancing cell division or cell expansion, or both. Although highly variable, the literature suggests that, generally, initiation and stimulation of lateral roots is favored over the elongation of primary roots, leading to more highly branched, shallower root systems. Such architectural shifts can render root systems less efficient, perhaps contributing to the lower specific root activities often reported. Allocation of carbon (C) to roots fluctuates through the life of the plant ; root functional and growth responses should therefore not be viewed as static. In annual crops, C allocation to belowground processes changes as vegetative growth switches to reproduction and maturation. Reductions in C allocation to roots over time might cause temporal shifts in root deployment, perhaps affecting root demography. However, significant changes in root turnover (defined here as root flux or mortality relative to total root pool size) as a result of decreased root longevities in crop plants are unlikely. Consideration of changing C allocation to roots, a more thorough understanding of the mechanistic controls on root longevity, and a better characterization of the rooting habits (life histories) of different crop species will further our understanding of how increasing atmospheric [CO # ] will affect root demography. This knowledge will lead the way toward a more thorough understanding of the linkage of atmosphere with belowground plant function and also that of plant function with soil biology and structure. Ultimately, successful modeling of global C and nitrogen (N) cycles will require empirical data concerning spatial and temporal deployment of roots for a range of crop species grown under different agricultural management systems.

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“…Plant species differ in the amount and form of N they take up (Aerts and Chapin, 2000), and these speciesspecific patterns of uptake modify the pools of N available to soil microbes and to other plants (Jackson et al, 1989;Jaeger et al, 1999a;Stark and Hart, 1997). Plants also indirectly affect N dynamics through their influence on microbial activity (Bardgett and Shine, 1999;Hobbie, 1992;Jackson et al, 1988) via root exudation, above-and below-ground litter inputs, and effects on microclimate (Eviner and Chapin, 2003b;Hodge et al, 1998;Jaeger et al, 1999b). While the effects of litter quantity and quality are not apparent until litter accumulates and decomposes in the soil (Jingguo and Bakken, 1997;Vinton and Burke, 1995), root exudates and species effects on microclimate may affect the soil microbial community from the early stages of plant growth.…”

Section: Introductionmentioning

confidence: 99%

Plant Colonizers Shape Early N-dynamics in Gopher-mounds

et al. 2005

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Disturbances by fossorial mammals are extremely common in many ecosystems, including the California annual grassland. We compared the impact of juveniles of four common plant colonizers (Aegilops triuncialis, Cerastium glomeratum, Aphanes occidentalis and Lupinus bicolor) on the pools and fluxes of N in mounds created by pocket gophers (Thomomys bottae Mewa). The mechanisms and magnitude of biotic N retention differed among plant species. In mounds colonized by Cerastium, Aphanes and Lupinus, the microbial N pool was significantly larger than the plant N pool, as is typical in California grasslands in the early spring, whereas in mounds colonized by Aegilops, there was a more equal distribution of biotic N between plant and microbial pools. A 1-day 15 N pulse field experiment demonstrated that plant species significantly differed in their effects on the distribution of isotopic N, with the N-fixing Lupinus leaving most (82%) 15 N as inorganic N in soil, whereas more 15 N was immobilized in plants or otherwise removed from the available soil pool in mounds colonized by other species. The impacts of early colonizers on N dynamics suggest that the identity of plant species that initially colonize gopher mounds may have important consequences on the dynamics of the overall grassland community.

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Characterisation and microbial utilisation of exudate material from the rhizosphere of Lolium perenne grown under CO2 enrichment

Cited by 88 publications

References 56 publications

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

Spatial and temporal deployment of crop roots in CO₂‐enriched environments

Plant Colonizers Shape Early N-dynamics in Gopher-mounds

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Characterisation and microbial utilisation of exudate material from the rhizosphere of Lolium perenne grown under CO2 enrichment

Cited by 88 publications

References 56 publications

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

Climate change goes underground: effects of elevated atmospheric CO2 on microbial community structure and activities in the rhizosphere

Spatial and temporal deployment of crop roots in CO2‐enriched environments

Plant Colonizers Shape Early N-dynamics in Gopher-mounds

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Product

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Spatial and temporal deployment of crop roots in CO₂‐enriched environments