scholarly journals Why is plant-growth response to elevated CO2 amplified when water is limiting, but reduced when nitrogen is limiting? A growth-optimisation hypothesis

2008 ◽  
Vol 35 (6) ◽  
pp. 521 ◽  
Author(s):  
Ross E. McMurtrie ◽  
Richard J. Norby ◽  
Belinda E. Medlyn ◽  
Roderick C. Dewar ◽  
David A. Pepper ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Elevated Co2 ◽  
Nitrogen Limitation ◽  
Growth Response ◽  
Nitrogen Concentration ◽  
N Uptake ◽  
Co2 Enrichment ◽  
Area Index ◽  
Oak Ridge ◽  
Leaf N

Experimental evidence indicates that the stomatal conductance and nitrogen concentration ([N]) of foliage decline under CO2 enrichment, and that the percentage growth response to elevated CO2 is amplified under water limitation, but reduced under nitrogen limitation. We advance simple explanations for these responses based on an optimisation hypothesis applied to a simple model of the annual carbon–nitrogen–water economy of trees growing at a CO2-enrichment experiment at Oak Ridge, Tennessee, USA. The model is shown to have an optimum for leaf [N], stomatal conductance and leaf area index (LAI), where annual plant productivity is maximised. The optimisation is represented in terms of a trade-off between LAI and stomatal conductance, constrained by water supply, and between LAI and leaf [N], constrained by N supply. At elevated CO2 the optimum shifts to reduced stomatal conductance and leaf [N] and enhanced LAI. The model is applied to years with contrasting rainfall and N uptake. The predicted growth response to elevated CO2 is greatest in a dry, high-N year and is reduced in a wet, low-N year. The underlying physiological explanation for this contrast in the effects of water versus nitrogen limitation is that leaf photosynthesis is more sensitive to CO2 concentration ([CO2]) at lower stomatal conductance and is less sensitive to [CO2] at lower leaf [N].

scholarly journals Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO<sub>2</sub> and contrasting site conditions

2013 ◽  
Vol 10 (11) ◽  
pp. 7703-7721 ◽  
Author(s):  
R. F. Grant
Keyword(s):  
Net Primary Productivity ◽  
National Laboratory ◽  
N Uptake ◽  
Co2 Enrichment ◽  
Ecosystem Model ◽  
Site Conditions ◽  
Biological Fixation ◽  
Oak Ridge ◽  
Soil N Mineralization ◽  
Nutrient Conservation

Abstract. If increases in net primary productivity (NPP) caused by rising concentrations of atmospheric CO2 (Ca) are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and nutrient conservation must also be increased. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root nutrient uptake and plant nutrient conservation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevated Ca in Free Air CO2 Enrichment (FACE) experiments in the USA at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin. More rapid soil N mineralization was found to be vital for simulating sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Greater nonsymbiotic N2 fixation from increased litterfall, root N uptake from increased root growth, and plant N conservation from increased translocation under elevated Ca were found to make smaller contributions to simulated increases in NPP. However greater nutrient conservation enabled larger increases in NPP with Ca to be modelled with coniferous vs. deciduous plant functional types. The effects of these processes on productivity now need to be examined over longer periods under transient rises in Ca and a greater range of site conditions.

Effects of repeated fertilization on needle longevity, foliar nutrition, effective leaf area index, and growth characteristics of lodgepole pine in interior British Columbia, Canada

2005 ◽  
Vol 35 (2) ◽  
pp. 440-451 ◽  
Author(s):  
Isaac G Amponsah ◽  
Philip G Comeau ◽  
Robert P Brockley ◽  
Victor J Lieffers
Keyword(s):  
British Columbia ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Response ◽  
Lodgepole Pine ◽  
Nitrogen Concentration ◽  
Nutrient Concentrations ◽  
Area Index ◽  
Needle Longevity ◽  
Effective Leaf Area Index

We investigated the effects of repeated fertilization (either periodically every 6 years or annual fertilization) on needle longevity and growth response in two juvenile lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands in the interior of British Columbia, Canada. Annual fertilization decreased needle longevity by 23% at the Kenneth Creek site and by 30% at Sheridan Creek, compared with the control treatments at each site. At Sheridan, repeated fertilization significantly increased effective leaf area index, foliated shoot length, and annual shoot growth. However, none of these variables was significantly altered by repeated fertilization at Kenneth. At both locations, fertilization elevated nutrient concentrations in the current year's foliage. Annual fertilization increased nitrogen concentration in mid-crown branches of retained cohorts (1998–2002) at both study sites. Furthermore, annual nitrogen addition apparently induced or exacerbated copper and iron deficiency in these stands, especially at Kenneth Creek, which may be related to the premature loss of foliage. Nutrient imbalance may also be related to poor effective leaf area index and growth response at Kenneth Creek. Stem growth efficiency declined with annual fertilization at Kenneth Creek because of accelerated turnover of needles, increased allocation of growth to branches, and probably reduced photosynthetic capacity.

The Influence of Nitrogen on the Elevated CO2 Response in Field-Grown Rice

1996 ◽  
Vol 23 (1) ◽  
pp. 45 ◽  
Author(s):  
LH Ziska ◽  
W Weerakoon ◽  
OS Namuco ◽  
R Pamplona
Keyword(s):  
Elevated Co2 ◽  
Growth Response ◽  
Oryza Sativa L ◽  
N Uptake ◽  
Root Production ◽  
N Availability ◽  
Above Ground Biomass ◽  
Co2 Response ◽  
Ground Biomass ◽  
N Supply

Rice (Oryza sativa L. cv. IR72) was grown in the tropics at ambient (345 μL L-1) or twice ambient (elevated, 700 μL L-1) CO2, concentration at three levels of supplemental nitrogen (N) (no additional N (N0), 90 kg ha-1 (N1) and 200 kg ha-1 (N2)) in open-top chambers under irrigated field conditions from seeding until flowering. The primary objective of the study was to determine if N supply alters the sensitivity of growth and photosynthesis of field-grown rice to enriched CO2. A second objective was to determine the influence of elevated CO2 on N uptake and tissue concentrations. Although photosynthesis was initially stimulated at the leaf and canopy level with elevated CO2 regardless of supplemental N supply, with time the photosynthetic response became highly dependent on the level of supplemental N, increasing proportionally as N availability increased. Similarly, a synergistic effect was noted between CO2 and N with respect to above-ground biomass with no effect of elevated CO2 observed for the No treatment. Most of the increase in above-ground biomass with increasing CO2 and N was associated with increased tiller and, to a lesser extent, root production. The concentration of above-ground N decreased at elevated CO2 regardless of N treatment; however, total above-ground N did not change for the N1 and N2 treatments because of the greater amount of biomass associated with elevated CO2. For rice, the photosynthetic and growth response to elevated CO2 may be highly dependent on the supply of N. If additional CO2 is given and N is not available, lack of sinks for excess carbon (e.g. tillers) may limit the photosynthetic and growth response.

scholarly journals Root growth and N dynamics in response to multi-year experimental warming, summer drought and elevated CO2 in a mixed heathland-grass ecosystem

2014 ◽  
Vol 41 (1) ◽  
pp. 1 ◽  
Author(s):  
M. F. Arndal ◽  
I. K. Schmidt ◽  
J. Kongstad ◽  
C. Beier ◽  
A. Michelsen
Keyword(s):  
Root Growth ◽  
Elevated Co2 ◽  
Environmental Changes ◽  
Nitrogen Concentration ◽  
N Uptake ◽  
Root Production ◽  
Summer Drought ◽  
Whole Plant ◽  
Grass Root ◽  
Biomass N

Ecosystems exposed to elevated CO2 are often found to sequester more atmospheric carbon due to increased plant growth. We exposed a Danish heath ecosystem to elevated CO2, elevated temperature and extended summer drought alone and in all combinations in order to study whether the expected increased growth would be matched by an increase in root nutrient uptake of NH4+-N and NO3– -N. Root growth was significantly increased by elevated CO2. The roots, however, did not fully compensate for the higher growth with a similar increase in nitrogen uptake per unit of root mass. Hence the nitrogen concentration in roots was decreased in elevated CO2, whereas the biomass N pool was unchanged or even increased. The higher net root production in elevated CO2 might be a strategy for the plants to cope with increased nutrient demand leading to a long-term increase in N uptake on a whole-plant basis. Drought reduced grass root biomass and N uptake, especially when combined with warming, but CO2 was the most pronounced main factor effect. Several significant interactions of the treatments were found, which indicates that the responses were nonadditive and that changes to multiple environmental changes cannot be predicted from single-factor responses alone.

Growth Pattern, Carbon Dioxide Exchange and Dry Weight Distribution in Wheat Growing Under Differing Photosynthetic Environments

1977 ◽  
Vol 4 (1) ◽  
pp. 99 ◽  
Author(s):  
RM Gifford
Keyword(s):  
Leaf Area ◽  
Negative Feedback ◽  
Growth Response ◽  
Co2 Enrichment ◽  
Net Photosynthesis ◽  
Carbon Dioxide Exchange ◽  
Co2 Uptake ◽  
Growth Responses ◽  
Reciprocal Effect ◽  
Area Index

Wheat (cv. WW15) was grown as a crop stand in different CO2 concentrations (ambient, ambient plus 200 � 20 vpm CO2, ambient minus 150 � 20 vpm CO2) from germination to maturity in naturally lit growth cabinets under winter or summer light conditions, at 21°C by day and 16°C at night. Ambient CO2 concentration during the daylight hours averaged 280-300 vpm. CO2 level had little effect on phenology of the mainshoot; most of the growth response was through tillering. From data on flag leaves in the winter light experiment, there was no indication of any positive or negative feedback on growth acting through maximum leaf net photosynthesis rate. Leaf area index was increased by CO2 at low light and the related self-shading acted as a negative feedback partially countering the effect due to an enhanced rate of CO2 uptake per unit leaf area. Dark respiratory CO2 loss represented a greater proportion of CO2 uptake in the light for the CO2-depleted crop than for the control crop. But the reciprocal effect was not evident for the enriched crop. Contrary to classical ideas on growth responses to variation of colimiting factors, the growth response to CO2 enrichment was relatively greater under the low radiation than the high radiation regime. The grain was the tissue most flexible in its responsiveness to changes in assimilation under the conditions of the summer experiment. For this crop, for which the grain yield of the control was very high (0.97 kgm-2), response of yield to CO2 enrichment corresponded to 0.25% per vpm.

scholarly journals Comparative Nitrogen Uptake and Distribution in Corn and Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
2007 ◽  
Vol 55 (2) ◽  
pp. 102-110 ◽  
Author(s):  
John L. Lindquist ◽  
Darren C. Barker ◽  
Stevan Z. Knezevic ◽  
Alexander R. Martin ◽  
Daniel T. Walters
Keyword(s):  
N Uptake ◽  
Soil Nutrient ◽  
Biomass Accumulation ◽  
Field Studies ◽  
Total Biomass ◽  
N Addition ◽  
N Content ◽  
Area Index ◽  
Leaf N Content ◽  
Leaf N

Weeds compete with crops for light, soil water, and nutrients. Nitrogen (N) is the primary limiting soil nutrient. Forecasting the effects of N on growth, development, and interplant competition requires accurate prediction of N uptake and distribution within plants. Field studies were conducted in 1999 and 2000 to determine the effects of variable N addition on monoculture corn and velvetleaf N uptake, the relationship between plant N concentration ([N]) and total biomass, the fraction of N partitioned to leaves, and predicted N uptake and leaf N content. Cumulative N uptake of both species was generally greater in 2000 than in 1999 and tended to increase with increasing N addition. Corn and velvetleaf [N] declined with increasing biomass in both years in a predictable manner. The fraction of N partitioned to corn and velvetleaf leaves varied with thermal time from emergence but was not influenced by year, N addition, or weed density. With the use of the [N]–biomass relationship to forecast N demand, cumulative corn N uptake was accurately predicted for three of four treatments in 1999 but was underpredicted in 2000. Velvetleaf N uptake was accurately predicted in all treatments in both years. Leaf N content (NL, g N m−2leaf) was predicted by the fraction of N partitioned to leaves, predicted N uptake, and observed leaf area index for each species. Average deviations between predicted and observed corn NLwere < 88 and 12% of the observed values in 1999 and 2000, respectively. Velvetleaf NLwas less well predicted, with average deviations ranging from 39 to 248% of the observed values. Results of this research indicate that N uptake in corn and velvetleaf was driven primarily by biomass accumulation. Overall, the approaches outlined in this paper provide reasonable predictions of corn and velvetleaf N uptake and distribution in aboveground tissues.

scholarly journals Modelling changes in nitrogen cycling to sustain increases in forest productivity under elevated atmospheric CO<sub>2</sub> and contrasting site conditions

2013 ◽  
Vol 10 (4) ◽  
pp. 6783-6837
Author(s):  
R. F. Grant
Keyword(s):  
Net Primary Productivity ◽  
National Laboratory ◽  
N Uptake ◽  
Co2 Enrichment ◽  
Ecosystem Model ◽  
Root Uptake ◽  
Biological Fixation ◽  
Oak Ridge ◽  
Soil N Mineralization ◽  
Plant Translocation

Abstract. If increases in net primary productivity (NPP) caused by rising concentrations of atmospheric CO2 (Ca) are to be sustained, key N processes such as soil mineralization, biological fixation, root uptake and plant translocation must be hastened. Simulating the response of these processes to elevated Ca is therefore vital for models used to project the effects of rising Ca on NPP. In this modelling study, hypotheses are proposed for changes in soil mineralization, biological fixation, root uptake and plant translocation with changes in Ca. Algorithms developed from these hypotheses were tested in the ecosystem model ecosys against changes in N and C cycling measured over several years under ambient vs. elevatedCa in Free Air CO2 Enrichment (FACE) experiments at the Duke Forest in North Carolina, the Oak Ridge National Laboratory forest in Tennessee, and the USDA research forest in Wisconsin, USA. Simulating more rapid soil N mineralization was found to be vital for modelling sustained increases in NPP measured under elevated vs. ambient Ca at all three FACE sites. This simulation was accomplished by priming decomposition of N-rich humus from increases in microbial biomass generated by increased litterfall modelled under elevated Ca. Simulating more rapid nonsymbiotic N2 fixation, root N uptake and plant N translocation under elevated Ca was found to make much smaller contributions to modelled increases in NPP, although such contributions might be greater over longer periods and under more N-limited conditions than those simulated here. Greater increases in NPP with Ca were also modelled with increased temperature and water stress, and with coniferous vs. deciduous plant functional types. These increases were also associated with changes in N cycling.

Effect of elevated CO2 on Vigna radiata and two weed species: yield, physiology and crop–weed interaction

2018 ◽  
Vol 69 (6) ◽  
pp. 617 ◽  
Author(s):  
Jay Prakash Awasthi ◽  
Kamlesh Singh Paraste ◽  
Meenal Rathore ◽  
Mayank Varun ◽  
Disha Jaggi ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Elevated Co2 ◽  
Vigna Radiata ◽  
Co2 Enrichment ◽  
Atmospheric Co2 ◽  
Green Gram ◽  
Weed Species ◽  
Test Species ◽  
Antioxidant Defence System ◽  
Species Specific

A field experiment was conducted in a free-air CO2 enrichment (FACE) facility to investigate the effect of elevated atmospheric CO2 on growth and physiology of green gram (Vigna radiata (L.) R.Wilczek) and associated weed species (Euphorbia geniculata Ortega and Commelina diffusa Burm.f.). Physiological and reproductive behaviour and interaction of the crop and two weed species under elevated CO2 was also studied. Plants were grown under ambient (390 ± 5 ppmv) and elevated (550 ± 50 ppmv) CO2. The results showed that growth, photosynthesis and carbonic anhydrase activity increased in all the test species. Stomatal conductance and transpiration decreased in V. radiata (5.1% and 30.5%, respectively) and C. diffusa (19% and 13.7%) but increased in E. geniculata (6.5% and 27.6%), suggesting a unique adaptive potential of E. geniculata at elevated CO2. Higher accumulation of reactive oxygen species (hydrogen peroxide and superoxide) was noticed at elevated CO2 in V. radiata than in E. geniculata and C. diffusa. Potential of E. geniculata to maintain redox homeostasis in its original state may provide an advantage over two other species in adaptation to climate change. Isoenzyme patterns of superoxide dismutase and stronger activity of antioxidant enzymes suggest species-specific differential regulation and induction of new isoforms under elevated CO2. Enrichment of atmospheric CO2 at a competitive density of weeds lowered the yield (12.12%) and quality of green gram seed, with diminished protein content (16.14% at ambient CO2 to 15.42% at elevated CO2) and enhanced carbohydrate content (3.11%). From the study, it may be concluded that a rise in atmospheric CO2 concentration affects plant performance in a species-specific manner. Among the three species, E. geniculata emerged as most responsive to elevated CO2, showing higher transpiration and stomatal conductance and a stronger antioxidant defence system in a higher CO2 atmosphere. At elevated CO2, weed–crop interaction altered in favour of weeds leading to considerable yield loss of green gram seed.

scholarly journals The Effect of Different Nitrogen Levels and Enrichment CO2 on the Nutrient Contents of Rice Cultivars

1970 ◽  
Vol 44 (2) ◽  
pp. 241-246 ◽  
Author(s):  
MA Razzaque ◽  
MM Haque ◽  
QA Khaliq ◽  
ARM Solaiman
Keyword(s):  
Elevated Co2 ◽  
Nitrogen Concentration ◽  
Co2 Enrichment ◽  
Rice Cultivars ◽  
Nutrient Contents ◽  
Plant Parts ◽  
Nitrogen Levels ◽  
Open Field Condition ◽  
Ambient Co2 ◽  
Key Words Rice

An experiment was conducted during the July -December of 2003 to determine the nutrient compositions of rice under CO2 enrichment of different levels of nitrogen supply. Rice plants were grown from seedlings to maturity inside open top chamber under elevated CO2 (570 ±50) ppm, ambient CO2 (~360ppm) and open field condition. Leaves and root were analyzed for C, N, Zn and Mg. C content was higher in the all plant parts of rice grown at elevated CO2 compare than ambient CO2 and field grown rice. Increased N supplies also increase C content of the plants. Nitrogen concentration was reduced in elevated CO2 compare than other grown condition. Modern variety (BRRIdhan 39) contained higher C than local cultivars (Khaskani and Shakkorkhora). Nitrogen concentration was decreased under elevated CO2 compare to other treatments. Key words : Rice cultivars, Enrichment CO2, C, N, Zn, Mg DOI: 10.3329/bjsir.v44i2.3680 Bangladesh J. Sci. Ind. Res. 44(2), 241-246, 2009   

Effects of water availability, nitrogen supply and atmospheric CO2 concentrations on plant nitrogen natural abundance values

2006 ◽  
Vol 33 (3) ◽  
pp. 219 ◽  
Author(s):  
William D. Stock ◽  
John R. Evans
Keyword(s):  
Stomatal Conductance ◽  
Water Supply ◽  
Elevated Co2 ◽  
Water Availability ◽  
Atmospheric Co2 ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations ◽  
Cape Gooseberry ◽  
Foliar Δ15n ◽  
Leaf N

The relative effects of soil N, water supply and elevated atmospheric CO2 on foliar δ15N values were examined. Phalaris arundinacea L. (Holdfast) and Physalis peruviana L. (Cape Gooseberry) were grown for 80 d with three water availability treatments, two atmospheric CO2 concentrations and four N supply rates. Elevated CO2 increased total plant biomass and N for each treatment and decreased allocation to roots, leaf N concentrations and stomatal conductance. Leaves had less negative leaf δ13C values under low water supply associated with decreased stomatal conductance and increased leaf N concentration, which decreased the ratio of intercellular to ambient CO2 concentration. The δ15N value of the supplied nitrate (4.15‰) was similar to the value for Phalaris leaves (4.11‰), but Cape Gooseberry leaves were enriched (6.52‰). The effects of elevated CO2 on leaf δ15N values were small, with Phalaris showing no significant change, while Cape Gooseberry showed a significant (P < 0.05) decline of 0.42 ‰. Variation in δ15N values was unrelated to stomatal conductance, transpiration, differential use of N forms or denitrification. Plants with low foliar N concentrations tended to be depleted in 15N. We suggest that changes in N allocation alter foliar δ15N values under different CO2 and water treatments.

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