Plant Respiration and Elevated Atmospheric CO 2 Concentration: Cellular Responses and Global Significance (original) (raw)
Related papers
Australian Journal of Botany, 1992
An analysis of elevated CO 2 effects (2-4 times ambient) on dark respiration rate and carbon content was undertaken for a wide range of plant species, using both published reports and new data. On average, leaf respiration per unit leaf area was slightly higher for plants grown at high CO 2 (16%), whereas a small decrease was found when respiration was expressed on a leaf weight basis (14%). For the few data on root respiration, no significant change due to high CO 2 could be detected. Carbon content of leaves and stem showed a small increase (1.2 and 1.7% respectively), whereas C-content of roots was not significantly affected. In both data sets direction of responses was variable. A sensitivity analysis of carbon budgets under elevated CO 2 identified changes in respiration rate, and to a lesser extent carbon content, as important factors affecting the growth response to elevated CO 2 in quite a number of cases. Any comprehensive analysis of growth responses to increased CO 2 should therefore include measurements of these two variables.
Plant Respiration and Climate Change Effects
The ongoing climate changes can affect many plant physiological processes. In turn, these effects on plants may result in a feedback between the climate change and the vegetation.
Respiration of crop species under CO2 enrichment
Physiologia Plantarum, 1985
Respiratory characteristics of wheat (Triticum aestivum L. cvs Gabo and WW15), mung bean (Vigna radiata L. Wilczek cv. Celera) and sunflower (Helianthus annuus L. cv. Sunfola) were studied in plants grown under a normal CO2 concentration and in air containing an additional 340 (or 250) μl l−1 CO2. Such an increase in global atmospheric CO2 concentration has been forecast for about the middle of the next century. The aim was to measure the effect of high CO2 on respiration and its components. Polarographic and, with wheat, CO2 exchange techniques were used. The capacity of the alternative pathway of respiration in roots was determined polarographically in the presence of 0.1 mM KCN. The actual rate of alternative pathway respiration was assessed by reduction in oxygen consumption caused by 10 mM salicylhydroxamic acid.Each species responded differently. In wheat, growth in high atmospheric CO2 was associated with up to 45% reduction in respiration by both roots and whole plants. Use of respiratory inhibitors in polarographic measurements on wheat roots implicated reduction in the degree of engagement of the alternative pathway as a major contributor to this reduced respiratory activity of high-CO2 plants. No change was found in the total sugar content per unit wheat root dry weight as a result of high CO2. In none of the species was there an increase in the absolute, or relative, contribution by the alternative pathway to total respiration of the root systems. Thus the improved photosynthetic assimilate supply of plants grown in high CO2 did not lead to increased diversion of carbon through the non-phosphorylating alternative pathway of respiration in the root. On the contrary, in wheat grown in high CO2 the reduced loss of carbon through that route must have contributed to their larger dry weight.
Does elevated atmospheric CO2concentration inhibit mitochondrial respiration in green plants?
Plant Cell and Environment, 1999
There is abundant evidence that a reduction in mitochondrial respiration of plants occurs when atmospheric CO 2 (C a) is increased. Recent reviews suggest that doubling the present C a will reduce the respiration rate [per unit dry weight (DW)] by 15 to 18%. The effect has two components: an immediate, reversible effect observed in leaves, stems, and roots of plants as well as soil microbes, and an irreversible effect which occurs as a consequence of growth in elevated C a and appears to be specific to C 3 species. The direct effect has been correlated with inhibition of certain respiratory enzymes, namely cytochromec-oxidase and succinate dehydrogenase, and the indirect or acclimation effect may be related to changes in tissue composition. Although no satisfactory mechanisms to explain these effects have been demonstrated, plausible mechanisms have been proposed and await experimental testing. These are carbamylation of proteins and direct inhibition of enzymes of respiration. A reduction of foliar respiration of 15% by doubling present ambient C a would represent 3 Gt of carbon per annum in the global carbon budget.
The impact of global elevated CO2 concentration on photosynthesis and plant productivity
2010
The alarming and unprecedented rise in the atmospheric concentration of greenhouse gases under global climate change warrants an urgent need to understand the synergistic and holistic mechanisms associated with plant growth and productivity. Photosynthesis is a major process of sequestration and turnover of the total carbon on the planet. The extensive literature on the impacts of climate change demonstrates both positive and negative effects of rising CO 2 on photosynthesis in different groups of higher plants. Significant variation exists in the physiological, biochemical and molecular responsiveness to elevated CO 2 atmosphere, among terrestrial plant species including those with C 3 , C 4 and crassulacean acid metabolic (CAM) pathways. However, the regulatory events associated with the inter-and intraspecific metabolic plasticity governed by genetic organization in different plants are little understood. The adaptive acclimation responses of plants to changing climate remain contradictory. This review focuses primarily on the impacts of global climate change on plant growth and productivity with special reference to adaptive photosynthetic acclimative responses to elevated CO 2 concentration. The effects of elevated CO 2 concentration on plant growth and development, source-sink balance as well as its interactive mechanisms with other environmental factors including water availability, temperature and mineral nutrition are discussed.
Ecological Research, 2005
Elevated CO 2 enhances photosynthesis and growth of plants, but the enhancement is strongly influenced by the availability of nitrogen. In this article, we summarise our studies on plant responses to elevated CO 2 . The photosynthetic capacity of leaves depends not only on leaf nitrogen content but also on nitrogen partitioning within a leaf. In Polygonum cuspidatum, nitrogen partitioning among the photosynthetic components was not influenced by elevated CO 2 but changed between seasons. Since the alteration in nitrogen partitioning resulted in different CO 2 -dependence of photosynthetic rates, enhancement of photosynthesis by elevated CO 2 was greater in autumn than in summer. Leaf mass per unit area (LMA) increases in plants grown at elevated CO 2 . This increase was considered to have resulted from the accumulation of carbohydrates not used for plant growth. With a sensitive analysis of a growth model, however, we suggested that the increase in LMA is advantageous for growth at elevated CO 2 by compensating for the reduction in leaf nitrogen concentration per unit mass. Enhancement of reproductive yield by elevated CO 2 is often smaller than that expected from vegetative growth. In Xanthium canadense, elevated CO 2 did not increase seed production, though the vegetative growth increased by 53%. As nitrogen concentration of seeds remained constant at different CO 2 levels, we suggest that the availability of nitrogen limited seed production at elevated CO 2 levels. We found that leaf area development of plant canopy was strongly constrained by the availability of nitrogen rather than by CO 2 . In a rice field cultivated at free-air CO 2 enrichment, the leaf area index (LAI) increased with an increase in nitrogen availability but did not change with CO 2 elevation. We determined optimal LAI to maximise canopy photosynthesis and demonstrated that enhancement of canopy photosynthesis by elevated CO 2 was larger at high than at low nitrogen availability. We also studied competitive asymmetry among individuals in an even-aged, monospecific stand at elevated CO 2 . Light acquisition (acquired light per unit aboveground mass) and utilisation (photosynthesis per unit acquired light) were calculated for each individual in the stand. Elevated CO 2 enhanced photosynthesis and growth of tall dominants, which reduced the light availability for shorter subordinates and consequently increased size inequality in the stand.
Plant Responses to Elevated CO 2
eLS, 2012
Carbon dioxide (CO 2) has two unique properties: physically it absorbs in the infra-red (heat) portion of the spectrum, and plays a role in maintaining global surface temperatures; secondly, it is the source of carbon for plant photosynthesis and growth. Recent, rapid anthropogenic increases in CO 2 have been well-characterised with respect to climatic change; less recognised is that increase in CO 2 will also impact how plants supply food, energy and carbon to all living things. At present, numerous experiments have documented the response of single leaves or whole plants to elevated CO 2 ; however, it is difficult to scale up or integrate these observations to plant biology in toto. To that end, a greater emphasis on multiple factor experiments for managed and unmanaged systems, in combination with simulative vegetative modelling, could increase our predictive capabilities regarding the impact of elevated CO 2 on plant communities (e.g. agriculture, forestry) of human interest. Advanced article Article Contents This is a US Government work and is in the public domain in the United States of America. eLS. www.els.net. John Wiley & Sons, Ltd
CO2 sequestration in plants: lesson from divergent strategies
Photosynthetica, 2011
Most organisms inhabiting earth feed directly or indirectly on the products synthesized by the reaction of photosynthesis, which at the current atmospheric CO 2 levels operates only at two thirds of its peak efficiency. Restricting the photorespiratory loss of carbon and thereby improving the efficiency of photosynthesis is seen by many as a good option to enhance productivity of food crops. Research during last half a century has shown that several plant species developed CO 2-concentrating mechanism (CCM) to restrict photorespiration under lower concentration of available CO 2. CCMs are now known to be operative in several terrestrial and aquatic plants, ranging from most advanced higher plants to algae, cyanobacteria and diatoms. Plants with C 4 pathway of photosynthesis (where four-carbon compound is the first product of photosynthesis) or crassulacean acid metabolism (CAM) may consistently operate CCM. Some plants however can undergo a shift in photosynthetic metabolism only with change in environmental variables. More recently, a shift in plant photosynthetic metabolism is reported at high altitude where improved efficiency of CO 2 uptake is related to the recapture of photorespiratory loss of carbon. Of the divergent CO 2 assimilation strategies operative in different oraganisms, the capacity to recapture photorespiratory CO 2 could be an important approach to develop plants with efficient photosynthetic capacity.