Root growth and functioning under atmospheric CO2 enrichment

Stulen, I.; Hertog, Jeroen den

doi:10.1007/978-94-011-1797-5_7

Cited by 84 publications

(132 citation statements)

References 66 publications

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“…The results on ryegrass and Douglas-firs suggest that the root/shoot ratios in these species would increase under elevated CO2. As stated by Stulen and Den Hertog (1993), root/shoot ratios based on dry matter production may be erroneous, because of the difficulty of quantitative recovery of all roots from the soil and the decomposition of dead roots during experiments. This view was strongly supported by Pregitzer et al (1995).…”

Section: Hypothesis 2 -A Shift Occurs In the Carbon Distribution Withmentioning

confidence: 99%

Elevated CO2 evokes quantitative and qualitative changes in carbon dynamics in a plant/soil system: mechanisms and implications

Gorissen¹

1995

Plant Soil

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It is hypothesized that carbon storage in soil will increase under an elevated atmospheric CO2 concentration due to a combination of an increased net CO2 uptake, a shift in carbon allocation pattern in the plant/soil system and a decreased decomposition rate of plant residues. An overview of several studies, performed in our laboratory, on the effects of elevated CO2 on net carbon uptake, allocation to the soil and decomposition of roots is given to test this hypothesis. The studies included wheat, ryegrass and Douglas-fir and comprised both short-term and long-term studies.Total dry weight of the plants increased up to 62%, but depended on nutrient availability. These results were supported by the data on net 14CO2 uptake. A shift in laC-carbon distribution from shoots to roots was found in perennial species, although this depended on nutrient availability.The decomposition experiments showed that roots cultivated at 700 #L L -1 CO2 were decomposed more slowly than those cultivated at 350 #L L -1 CO2. Even after two growing seasons differences up to 13% were observed, although this was found to be dependent on the nitrogen level at which the roots were grown.Both an increased carbon allocation to the soil due to an increased carbon uptake, whether or not combined with a shift in distribution pattern, and a decreased decomposition of root residues will enhance the possibilities of carbon sequestration in soil, thus supporting our hypothesis. However, nutrient availability and the response of the soil microbial biomass (size and activity) play a major role in the processes involved and require attention to clarify plant/soil responses in the long term with regard to sustained stimulation of carbon input into soils and the decomposability of roots and rhizodeposition, Soil texture will also have a strong effect on decomposition rates as a result of differences in the protecting capacity for organic matter. More detailed information on these changes is needed for a proper use of models simulating soil carbon dynamics in the long term.

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Section: Hypothesis 2 -A Shift Occurs In the Carbon Distribution Withmentioning

confidence: 99%

Elevated CO2 evokes quantitative and qualitative changes in carbon dynamics in a plant/soil system: mechanisms and implications

Gorissen¹

1995

Plant Soil

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“…Carbon allocation determines plant health and yield under virtually all conditions and plays apivotal role in the CO2 response. In a recent review, Stulen and den Hertog (1993) conclude the assumption that a larger proportion of the extra dry matter produced under CO2 enrichment is allocated to roots needs critical reexamination, which has been echoed by other researchers (Norby, 1994;Rogers et al, 1994). It has been further suggested that any reconsideration of R:S should include thought about why the parameter is of interest (Norby, 1994).…”

Section: Introductionmentioning

confidence: 99%

Root to shoot ratio of crops as influenced by CO2

et al. 1995

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Crops of tomorrow are likely to grow under higher levels of atmospheric CO2. Fundamental crop growth processes will be affected and chief among these is carbon allocation. The root to shoot ratio (R:S, defined as dry weight of root biomass divided by dry weight of shoot biomass) depends upon the partitioning of photosynthate which may be influenced by environmental stimuli. Exposure of plant canopies to high CO2 concentration often stimulates the growth of both shoot and root, but the question remains whether elevated atmospheric CO2 concentration will affect roots and shoots of crop plants proportionally. Since elevated CO2 can induce changes in plant structure and function, there may be differences in allocation between root and shoot, at least under some conditions. The effect of elevated atmospheric CO2 on carbon allocation has yet to be fully elucidated, especially in the context of changing resource availability. Herein we review root to shoot allocation as affected by increased concentrations of atmospheric CO2 and provide recommendations for further research. Review of the available literature shows substantial variation in R:S response for crop plants. In many cases (59.5%) R:S increased, in a very few (3.0%) remained unchanged, and in others (37.5%) decreased. The explanation for these differences probably resides in crop type, resource supply, and other experimental factors. Efforts to understand allocation under CO2 enrichment will add substantially to the global change response data base.Abbreviations: R:S -root to shoot ratio, dry weight basis

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“…Many studies have focused on changes in biomass allocation within the plant, examining root to shoot ratios, amount of fine roots, etc. Stulen and den Hertog, 1993). Roots may also adjust their physiology to acquire limiting nutrients through a variety of mechanisms: increasing uptake of particular nutrients per unit root surface (Garnier, 1991), producing enzymes capable of releasing nutrients from SOM and making them available for uptake (e.g.…”

Section: Carbon "Loss" Through Exudation Under Elevated C02 -A Plmentioning

confidence: 99%

“…Beyond litter quality, however, there are other probably equally important ways that changes in atmospheric CO2 concentrations may drive altered carbon storage in soils. Elevated CO2 may influence dynamics of SOM processing by causing altered rhizodeposition (O'Neill, 1994;Stulen and den Hertog, 1993;Van de Geijn and Van Veen, 1993;Van Veen et al, 1991), by changing soil water content via altered water use by plants (Hungate et al, 1996a), or both ( Figure 1). Altered decomposition will, in turn, affect nutrient availability to plants either positively (Zak et al, 1993) or negatively (Diaz et al, 1993), ultimately feeding back to influence net primary productivity.…”

Section: Rhizodeposition Under Elevated Co2-a Soil Perspectivementioning

confidence: 99%

“…There are a number of recent, excellent reviews of root and rhizosphere response to elevated CO2 (Norby, 1994;O'Neill, 1994;Rogers et al, 1994;Stulen and den Hertog, 1993;Van Veen et al, 1991). In addition, ecosystem studies examining the feedbacks among belowground carbon storage, nutrient availability and atmospheric CO2, have noted the interaction between rhizodeposition and microbial processes (Diaz et al, 1993;Wood et al, 1994;Zak et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

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Influence of rhizodeposition under elevated CO2 on plant nutrition and soil organic matter

Cardon

1995

Plant Soil

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Atmospheric CO2 concentrations can influence ecosystem carbon storage through net primary production (NPP), soil carbon storage, or both. In assessing the potential for carbon storage in terrestrial ecosystems under elevated CO2, both NPP and processing of soil organic matter (SOM), as well as the multiple links between them, must be examined. Within this context, both the quantity and quality of carbon flux from roots to soil are important, since roots produce specialized compounds that enhance nutrient acquisition (affecting NPP), and since the flux of organic compounds from roots to soil fuels soil microbial activity (affecting processing of SOM).From the perspective of root physiology, a technique is described which uses genetically engineered bacteria to detect the distribution and amount of flux of particular compounds from single roots to non-sterile soils. Other experiments from several labs are noted which explore effects of elevated CO2 on root acid phosphatase, phosphomonoesterase, and citrate production, all associated with phosphorus nutrition. From a soil perspective, effects of elevated CO2 on the processing of SOM developed under a C4 grassland but planted with C3 California grassland species were examined under low (unamended) and high (amended with 20 g m -2 NPK) nutrients; measurements of soil atmosphere ~ 13C combined with soil respiration rates show that during vegetative growth in February, elevated CO2 decreased respiration of carbon from C4 SOM in high nutrient soils but not in unamended soils.This emphasis on the impacts of carbon loss from roots on both NPP and SOM processing will be essential to understanding terrestrial ecosystem carbon storage under changing atmospheric CO2 concentrations.

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Root growth and functioning under atmospheric CO2 enrichment

Cited by 84 publications

References 66 publications

Elevated CO2 evokes quantitative and qualitative changes in carbon dynamics in a plant/soil system: mechanisms and implications

Elevated CO2 evokes quantitative and qualitative changes in carbon dynamics in a plant/soil system: mechanisms and implications

Root to shoot ratio of crops as influenced by CO2

Influence of rhizodeposition under elevated CO2 on plant nutrition and soil organic matter

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