1^4^Ackerly,D D^Coleman,J S^Morse,S R^Bazzaz,F A^1992^1^CO2 and Temperature Effects on Leaf Area Production in Two Annual Plant Species^2^73^^1260-1269^^^^^^^^^^3^^^^^^^^^^^Abutilon theophrasti/Amaranthus retroflexus;sϝ_ZÀ}&>!&&C^1^Ecology[PQR&Dt&"O&\&D t&Du&|Au&|But&|tV2r^ZYXA^1^We studied leaf area production in two annual plant species, _Abutilon theophrasti_ and _Amaranthus retroflexus_, under three day/night temperature regimes (18/14C, 28/22C, and 28/31C) and two concentrations of carbon dioxide (400 and 700 uL/L). The production of whole-plant leaf area during the first 30 d of growth was analyzed in terms of the leaf initiation rate, leaf expansion, individual leaf area, and, in _Amaranthus_, production of branch leaves. Temperature and CO2 inf% luenced leaf area production through stem (the plastochron index), and through shifts in the relationship between whole-pl) ant leaf area and the number of main stem nodes. In _Abutilon_, leaf initiation rate was highest at 38C, but area of indi- vidual leaves was greatest at 28C. Total leaf area was greatly reduced at 18C due to slow leaf initiation rates. Elevate0 d CO2 concentration increased leaf initiation rate at 28C, resulting in an increase in whole-plant leaf area. In _Amarant3 hus_, leaf initiation rate increased with temperature, and was increased by elevated CO2 at 28C. Individual leaf area wasA greatest at 28C, and was increased by elevated CO2 at 28C but decreased at 38C. Branch leaf area displayed a similar response to CO2, but was greater at 38C. Overall, whole-plant leaf area was slightly increased at 38C relative to 28C, aDnd elevated CO2 levels resulted in increased leaf area at 28C but decreased leaf area at 38C. The effects on leaf area cTlosely parallel rates of biomass accumulation in the same experiment, suggesting that responses of developmental processesW to elevated CO2 and interacting factors may play an important role in mediating effects on plant growth.uPVښ*[2^1^Acock,B^1990^3^Effects of CO2 on Photosynthesis, Plant Growth and Other Processes^Impact of CO2, Trace Gases, and Clim^ate Change on Global Agriculture^American Society of Agronomy^Madison, Wisconsin^45-60^^^^^^^ASA Special Publication No. 53^^^^^^^^^^^^^^^^^^^^^^^^Kimball,BA^Rosenberg,NJ^Allen,LH,Jri&4t tCVt\ut t1TtJctPt=Vtb3^3^Acock,B^Acock,M C^Pasternak,D^1990^1^Interactions of CO2 Enrichment and Temperature on Carbohydrate Production and Acciumulation in Muskmelon Leaves^3^115^^525-529^^^^^^^^^^7^^^^^^^^^^^muskmelon/Cucumis meloL. XX B~. CC^5^J. Amer. Soc. Hort. Sci.6&P& &&&@&& S~X؊}ǀtttttmA^5^We examined how temperature and stage of vegetative growth affect carbohydrate production and accumulation in _Cucumisu melo_ L. 'Haogen' grown at various CO2 concentrations ([CO2]). Carbohydrate production was measured by net assimilation rate either on a leaf-area basis (NARa) or a leaf dry-weight basis (NARw); carbohydrate accumulation was measured by leaf sxtarch plus sugar content. Twenty-four- and 35-day-old muskmelon plants were grown for 11 days in artificially lighted cabinets at day/night temperatures of 20/20 or 40/20C and at [CO2] of 300 or 1500 uL/L. NARa and NARw both increased with increasing [CO2], but the CO2 effect was smaller at low temperature, especially for plants at the later stage of vegetative growth. NARw was a better indicator of total dry-weight gain than was NARa. Both suboptimal temperatures and CO2 enrichment caused carbohydrates to accumulate in the leaves at both stages of vegetative growth. NARw was correlated negatively with !leaf starch plus sugar content. The rate of decrease in NARw with increasing leaf starch plus sugar content was significan"tly greater for CO2-enriched plants. Leaf starch plus sugar content >0.03 to 0.04 kg/kg of leaf residual dry weight at the# end of a dark period may indicate that temperature is suboptimal for growth. Plants grown at the same temperature had hig$her leaf starch plus sugar content if they were CO2-enriched than if grown in ambient [CO2], suggesting that an optimal temperature for growth in ambient [CO2] may be suboptimal in elevated [CO2].@&&2'&>tQ3&6S~&Dt tS~ &4^4^Acock,B^Acock,M C^Reddy,V R^Baker,D N^1985^5^The Simulation, with GLYCIM, of Soybean Crops Grown in the Field and at V'arious CO2 Concentrations in Open-top Chambers during 1982^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S(. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean^^011 in Green Report Series^Response of Vegetation to Carbon Dioxide^^S~@&tG;u:&>u&>#w&uS~Z&S~@&uC*5^7^Acock,B^Baker,D N^Reddy,V R^McKinion,J M^Whisler,F D^Del Castillo,D^Hodges,H F^1982^5^Soybean Responses to Carbon Diox+ide: Measurement and Simulation 1981^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture,, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^004 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^~uG~us~~ -6Z~\~D ^~D\DD~$s~^RV.6^2^Acock,B^Allen,LH,Jr^1985^3^Crop Responses to Elevated Carbon Dioxide Concentrations^Direct Effects of Increasing Carbo/n Dioxide on Vegetation^Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^53-97^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,JD~DDDь\s"6N~D${6N~|>N~6N~&&t 8& 17^2^Acock,B^Pasternak,D^1986^3^Effects of CO2 Concentration on Composition, Anatomy, and Morphology of Plants^Physiology, 2Yield and Economics^CRC Press, Inc.^Boca Raton, Florida^41-52^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^12^^^^^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,BAl,B A &Dt&T&D@t&Dt&tr v &Du &t⇨uZX4A^11^In summary, we can say that species differ in their response to high CO2. Plants which are using CAM are relatively u5nresponsive. Other plants with the C4 pathway show modest dry weight gains but large reductions in transpiration rate. Pla6nts which only have the C3 pathway, or well-watered CAM plants which are behaving like C3 plants, exhibit modest reduction7s in transpiration rate and large gains in dry weight, resulting in a variety of changes in plant composition, anatomy, an8d morphology. We know too little to even begin dividing C3 species into response groups. However, we can describe a typica9l or average response as follows. All organs on the plants become heavier with roots gaining proportionally more dry weigh:t than stems, and stems more than leaves. The additional dry matter in the root is mainly used to increase root length wit;h very little going to increase the density of the root tissue. Additional dry matter going to the stem causes increases ir which is probably greater than can be explained by the increase in number of mesophyll cell layers, although no one has  ?even done a definitive experiment on this. Finally, there is an increase in starch accumulating in the leaves which, depen@ding on the circumstances, can be very large. Branch and tiller numbers are frequently increased, as are the number of flowers. Either the weight or number of individual fruits is increased.8s@+CJJXS28+@I[WPS3B8^5^Acock,B^Reddy,V R^Hodges,H F^Baker,D N^McKinion,J M^1985^1^Photosynthetic Response of Soybean Canopies to Full-Season !Carbon Dioxide Enrichment^4^77^^942-947^^^^^^^^^^15^^^^^^^^^^^soybean/Glycine maxx(L.) Merr.T_PSQV5Y: |<C^13^Agron. J.5&|Du=:u2&L F&< t:T13^Y[XPSQR&tt2N$:T15:$EA^13^Global atmospheric CO2 concentration ([CO2]) is increasing as a result of the burning of fossil fuels. At present the+Fre is little information about how agronomic crops will respond to future high [CO2]. To investigate the basic process thaGt will be most affected, soybean canopies were continuously exposed to various [CO2] and photosynthetic rates were measure-Hd throughout the growing season. Soybean was grown to physiological maturity in sunlit controlled-environment chambers in 9ICO2 concentrations of 330, 450, 600 and 800 uL/L. Carbon dioxide fluxes were measured on the canopies at 15-min intervals Jevery day and used to calculate photosynthetic and respiration rates. Gross photosynthetic rate increased with each increm<Kent in [CO2] regardless of stage of development, but there was considerable day-to-day and seasonal variation. Seasonal chCLanges in photosynthetic rate were associated with developmental changes in the crop. Photosynthetic rates were low during Mearly vegetative development, even after the canopy had closed, but increased threefold just before flowering to reach a pGNeak during flowering at stage R2. They then decreased by 30% or more until just before the start of pod expansion (R3) whePOn a 45% increase occurred. Thereafter, photosynthetic rates decreased slowly and continuously to final harvest. The daily Pcurves of photosynthetic rate _vs._ photosynthetic photon flux density were further analyzed to determine canopy light utiSQlization efficiency () and canopy conductance to CO2 transfer (). Plants grown in 800 uL/L [CO2] had a value of that a\Rveraged about 40% higher than that for plants grown in 330 uL/L and a value of that averaged about 24% lower for the seaSson. Differences in between these treatments were significant throughout the season, while initial differences in betw_een treatments became less obvious after late vegetative growth stage VII.2t&G2t&G3t&G 3 t&GjU9^7^Acock,B^Reddy,V R^Whisler,F D^Baker,D N^McKinion,J M^Hodges,H F^Boote,K J^1983^5^The Soybean Crop Simulator GLYCIM: MoVdel Documentation^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.m$w, Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^002 in Green Report Series^Response of Vegetation to Carbon {X10^7^Acock,B^Reddy,V R^Del Castillo,D^Hodges,H F^Baker,D N^McKinion,J M^Whisler,F D^1983^5^Soybean Responses to Carbon DioYxide: Measurement and Simulation 1982^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of AgriculturZe, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^008 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^ PSQRVU3MUEU?EU tsJ tE t%r\11^2^Acock,B^Trent,A^1991^5^The Soybean Crop Simulator GLYCIM: Documentation for the Modular Version 91^U.S. Dept. of Ener]gy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^017 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^t-< t(< t#<t<_12^3^Aizawa,K^Nakamura,Y^Miyachi,S^1985^1^Variation of Phosphoenolpyruvate Carboxylase Activity in _Dunaliella_ Associated` with Changes in Atmospheric CO2 Concentration^128^26^^1199-1203^^^^^^^^^^21^^^^^^^^^^^Dunaliella tertiolecta/Dunaliella bioculata/Dunaliella viridis/Porphyridium cruentumm3 tփs<3;rr;r@uBy ^YCC^19^Plant Cell Physiol.&g RQ&g0uYZPSQRVWSsu^&wv&w&G'u։S&&G [P&GcA^19^In _Dunaliella tertiolecta_, _D. bioculata_ and _D. viridis_ the activities of phosphoenolpyruvate carboxylase and cadrbonic anhydrase were higher in the cells grown in ordinary air (low-CO2 cells) than in those grown in air enriched with 1e-5% CO2 (high-CO2 cells), whereas in _Porphyridium cruentum_ R-1 there was no difference in phosphoenolpyruvate carboxylasfe activity between these two types of cells. Apparent Km (NaHCO3) values for photosynthesis in low-CO2 cells of all speciegs tested were smaller than those in high-CO2 cells. Most of the 14C was incorporated into 3-phosphoglycerate, sugar mono- hand di-phosphates during the initial periods of photosynthetic NaH14CO3-fixation, indicating that both types of cells in _D. tertiolecta_ are C3 plants.y ^3 twPSQRVWb3ۊ@ ^r%2&N3ɾ &j13^3^Akey,D H^Kimball,B A^Mauney,J R^1988^1^Growth and Development of the Pink Bollworm,_ Pectinophora gossypiella_ (Lepidkoptera: Gelechiidae), on Bolls of Cotton Grown in Enriched Carbon Dioxide Atmospheres^6^17^^452-455^^^^^^^^^^24^^^^^^^^^^^cotton/Gossypium hirsutummL. FQnYsS&&W&O[ & u6& u & u &O$&O$0^NtsFC^22^Environ. Entomol.42҃t#2ᰀtt^Y PQVPQVrʚd${su^YXSnA^22^The pink bollworm, _Pectinophora gossypiella_ (Saunders), was reared on the bolls of cotton plants grown in CO2-enricohed (649 uL/L) and ambient (371 uL/L) chambers and in two open field plots, one with free-air CO2 enrichment (522 uL/L) anpd one without enrichment (ambient CO2, 360 uL/L). The effects of increased CO2 levels on growth and development were examiqned. There was no difference in pupal weights of pink bollworm raised on CO2-enriched cotton compared with those raised onr ambient CO2 cotton (26.80 versus 26.64 mg, respectively). Also, there was no difference in developmental time (21-27 d). sAnalysis of percent seed damage by larvae showed no differences between CO2-enriched and ambient CO2 cotton. These resultst were attributed to the nutritional qualities of the seed remaining the same (specifically the carbon:nitrogen ratio) despite CO2 and photosynthetic changes in the plant.t,ltr_r t _ F F ]_Y[XZR2Rv14^2^Akey,D H^Kimball,B A^1989^1^Growth and Development of the Beet Armyworm on Cotton Grown in an Enriched Carbon Dioxide Atmosphere^7^14^^255-260^^^^^^^^^^27^^^^^^^^^^^cotton/Gossypium hirsutummL.^€~ t2tĚ__rFlC^25^Southwestern Entomol.GDLVydr%^F FuPbkPr*X=o&+15^1^Allen,L H,Jr^1991^3^Effects of Increasing Carbon Dioxide Levels and Climate Change on Plant Growth, Evapotranspiration, and Water Resources^Managing Water Resources in the West under Conditions of Climate Uncertainty; 1990 Nov. 14-16; Scot-tsdale, Arizona^National Academy Press^Washington, D.C.^101-147^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^^^^^^^^^Committee on Climate Uncertainty and Water Resources Management8r>u&]&Ùt+016^1^Allen,L H,Jr^1992^1^Free-Air CO2 Enrichment Field Experiments: An Historical Overview^8^11^^121-134^^0;9u;>t;&SC^29^Crit. Rev. Plant Sci.=?Nv;5u;6t.`T5633҇13tC9;]_^Y[V u u17^1^Allen,L H,Jr^1990^1^Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants^9^19^^15-?34^^^^^^^^^^333v&D u3&\ &t VvK^6Hdؿ9Vv&\&]&\%]E&| t&&D &d &t fKC^31^J. Environ. Qual. &DE&DE&]Y]&D2 W> uv&t&| uuK6H]3&t t@[WA^31^As global population increases and industrialization expands, carbon dioxide (CO2) and toxic air pollutants can be exNpected to be injected into the atmosphere at increasing rates. This analysis reviews a wide range of direct plant responseds to rising CO2, increasing levels of gaseous pollutants, and climate change, and potential interactions among the factors. Although several environmental interactions on stomata and foliage temperatures are reviewed briefly, a comprehensive refview of effects of potential climatic change on plants is not a major objective of this analysis. Research shows that elevwated CO2 increases photosynthetic rates, leaf area, biomass, and yield. Elevated CO2 also reduces transpiration rate per uznit leaf area, but not in proportion to reduction of stomatal conductance, because foliage temperature tends to rise. With increasing leaf area and foliage temperature, water use per unit land area is scarcely reduced by elevated CO2. Increases in photosynthetic water-use efficiency are caused primarily by increased photosynthesis rather than reduced transpiration. Gaseous pollutants (O3, SO2, NOx, H2S) affect plants adversely primarily by entry through the stomata. An example calculation showed that reduction in stomatal conductance by doubled CO2 could potentially reduce the effects of ambient O3 and SO2 by 15%. However, information on the interaction of CO2 and air pollutants is scanty. More research is needed on these interactions, because regional changes in air pollutants are occurring concurrently with global changes in CO2.o4:r$18^2^Allen,L H,Jr^Beladi,S E^1990^5^Free-Air CO2 Enrichment (FACE): Analysis of Gaseous Dispersion Arrays for the Study of Rising Atmospheric CO2 Effects on Vegetation. 1983-1989 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Div#6ision, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^^^057 in Green Report Seri19^4^Allen,L H,Jr^Bisbal,E C^Campbell,W J^Boote,K J^1990^1^Carbon Dioxide Effects on Soybean Developmental Stages and Expansive Growth^10^49^^124-131^^^^^^^^^^37^^^^^^^^^^^soybean/Glycine maxx(L.) Merr.ZSQRVW5NP9RTr>wC^35^Soil and Crop Sci. Soc. Fla. Proc.dfd؉=ԉ?ԸbءhYj]l n[oWpXqYrZsVtA^35^Crop productivity is expected to increase as atmospheric carbon dioxide (CO2) continues to rise. The purpose of this paper is to examine the response of soybean [_Glycine max_ (L.) Merr., cv. Bragg] stages of development and plant size to CO2 concentration during four experiments (1981-1984) in outdoor controlled-environment chambers. Attached lysimeters contained Arredondo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult). Air temperature and dewpoint temperature were controlled to common set-points within each year with CO2 concentration being the treatment variable among chambers. Vegetative and reproductive developmental stages were determined at frequent intervals during each experiment. Growth parameters of mainstem height, total mainstem plus branch stem length, number of mainstem nodes with branches, mainstem diameter, and leaf areas were measured during at least one experiment. Vegetative stages progressed slightly faster and the final number of nodes was slightly greater with increased CO2 concentration. All size parameters clearly increased with increasing CO2 concentration. Growth responses per unit CO2 concentration change were greater over the subambient range (160 to 330 umol/mol) than over the superambient range (330 to 990 umol/mol). For soybean, plant expansive growth will increase as atmospheric CO2 continues to rise, whereas direct effects of CO2 (without interaction of potential climatic changes) will have little effect on phenology.X[1ș&X[&X[+ڋȋ&X[ȋ&X[ȋ&X[##&X[320^4^Allen,L H,Jr^Bisbal,E C^Boote,K J^Jones,P H^1991^1^Soybean Dry Matter Allocation under Subambient and Superambient Levels of Carbon Dioxide^4^83^^875-883^^^^^^^^^^40^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.ƀt҃C^38^Agron. J.ڒt ҃>tƀt҃ǀt t t tA^38^Rising atmospheric carbon dioxide concentration [CO2] is expected to cause increases in crop growth and yield. The objective of this study was to investigate effects of subambient, as well as superambient, [CO2] on soybean [_Glycine max_ (L.) Merr.] dry matter production and allocation for two reasons: to assess response of plants to prehistoric as well as fu-ture expected CO2 levels and to increase confidence in [CO2] response curves by imposing a wide range of [CO2] treatments. Soybean was grown in outdoor, sunlit, controlled-environment chambers at CO2 levels of 160, 220, 280, 330, 660, and 990 u0mol (CO2)/mol (air). Total dry matter growth rates during the linear phase of vegetative growth were 5.0, 8.4, 10.9, 12.5,= 18.2, and 20.7 g/m2/d for the above respective [CO2]. Samples taken from 24 to 94 d after planting showed that the percentage of total plant mass in leaf trifoliates decreased with increasing [CO2] whereas the percentage in structural componen@ts (petioles and stems) increased. At final harvest the respective [CO2] treatments resulted in 38, 53, 62, 100, 120 and 9K2% seed yield with respect to the 330 umol/mol treatment. Total dry weight responses were similar. Late season spider mite damage of the 990 and 280 umol/mol treatments reduced yields. These data confirm not only that rising CO2 should increaseO plant growth, but also that plant growth was probably seriously limited by atmospheric [CO2] in preindustrial revolution \times back to the previous global glaciation.E~ tM&%E &!E ]EWn*_ub21^8^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Vu,C V^Valle,R^Campbell,W J^1982^5^Effects of Increased Carbon _Dioxide on Photosynthesis and Agricultural Productivity of Soybeans. 1981 Progress Report^U.S. Dept. of Energy, Carbon Diobxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^003 in Green Report Series^Response of Vegetation to Carbon Dioxide^^ Dioxide^^PSQRVWU&>&[22^10^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Vu,C V^Valle,R R^Campbell,W J^Harris,P R^Heimburg,K F^1984^5^Effects of Increased Carbon Dioxide and Water Stress Interactions on Photosynthesis, Transpiration, and Productivity of Soybeans. 1983 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^014 in Green Report Series^Response of Vegetation to Carbon Dioxide^^n Dioxide^^&dGs6 ~| ~X u tt%523^8^Allen,L H,Jr^Boote,K J^Jones,J W^Jones,P H^Valle,R R^Acock,B^Rogers,H H^Dahlman,R C^1987^1^Response of Vegetation to Rising Carbon Dioxide: Photosynthesis, Biomass, and Seed Yield of Soybean^11^I^^1-14^^^^^^^^^^45^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.H122ɿr@>' %5F %'F fP %YF_^[r;C^43^Global Biogeochem. Cycles&v = u Ms鉅Wf22sv>W>tsNV A^43^Elevated carbon dioxide throughout the lifespan of soybean causes an increase in photosynthesis, biomass, and seed yield. A rectangular hyperbola model predicts a 32% increase in soybean seed yield with a doubling of carbon dioxide from 315 to 630 ppm and shows that yields may have increased by 13% from about 1800 A.D. to the present due to global carbon dioxide increases. Several other sets of data indicate that photosynthetic and growth response to rising carbon dioxide of many species, including woody plants, is similar to that of soybean. Calculations suggest that enough carbon could be sequestered annually from increased photosynthesis and biomass production due to the rise in atmospheric carbon dioxide from 315 ppm in 1958 to about 345 ppm in 1986 to reduce the impact of deforestation in the tropics on the putative current flux of carbon from the biosphere to the atmosphere.FȉF̉F҉FЉF։F@FʉF΋3FƋ1FvĿc$6F~6F624^7^Allen,L H,Jr^Boote,K J^Jones,J W^Mishoe,J W^Jones,P H^Valle,R R^Bisbal,E C^1985^5^Subambient and Superambient Carbon Dioxide Effects on Growth, Nonstructural Carbohydrates, Biochemistry of Photosynthesis and Transpiration of Soybeans. 1984 Progress Report^U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv.," Washington, D.C^^^^^^^^^^^^^^^^^^^^^^^^soybean/Glycine max^^031 in Green Report Series^Response of Vegetation to Carbon D25^2^Allen,L H,Jr^Boote,K J^1992^3^Vegetation, Effect of Rising CO2^Encyclopedia of Earth System Science^Academic Press, Inc.^New York^409-416^^^^4^^^^^^^^^^^^^^^^^^^^^^Ƅ_^mcwW u^NV t7rp^_N]ҍ^^^^^^^^^^^^^^^^^^^^^^^^^Shands,WE^Hoffman,JSNV^ t 닋^Ftr&E-26^4^Allen,L H,Jr^Drake,B G^Rogers,H H^Shinn,J H^1992^1^Field Techniques for Exposure of Plants and Ecosystems to Elevated CO2 and Other Trace Gases^8^11^^85-119^^0~tF܉FtF׈c DŽ[Ƅ_.&t ^N&fnC^49^Crit. Rev. Plant Sci.fN6v t2J*r+*W%5)55%N%NW 27^5^Allen,L H,Jr^Valle,R R^Mishoe,J W^Jones,J W^Jones,P H^1990^1^Soybean Leaf Gas Exchange Responses to CO2 Enrichment^10^49^^192-198^^^^^^^^^^53^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.[^6:s.S^r[[ a6:rad6:r F\C^51^Soil and Crop Sci. Soc. Fla. Proc.NV*6 _ZY[^K}M3ێF&Cu OFQu!3c 3VȉFƋ]28^5^Allen,L H,Jr^Vu,J C V^Valle,R R^Boote,K J^Jones,P H^1988^1^Nonstructural Carbohydrates and Nitrogen of Soybean Grown `under Carbon Dioxide Enrichment^12^28^^84-94^^^^^^^^^^56^^^^^^^^^^^soybean/Glycine maxx (L.) Merr.c 3 t<3eC^54^Crop Sci.c 3^ t<N剕A?qoc 35 t 3#, uJGusc 3 tgA^54^Carbon dioxide (CO2) concentration has been rising in the atmosphere for over a century. This study was conducted to determine the effects of anticipated future levels of CO2 on nonstructural carbohydrates and N of soybean [_Glycine max_ (jL.) Merr. cv. Bragg]. Plants were grown at Gainesville, FL from seed to maturity in six sunlit, controlled-environment chaumbers that maintained CO2 at 330, 330, 450, 600, 800, and 800 umol (CO2)/mol (air). Attached lysimeters contained Arredondyo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult). Leaflet blades were sampled five times per day at 48 a{nd 69 d after planting (DAP). At 48 DAP, average daytime starch conc. of leaflets increased with increasing CO2 from 85 g/|kg of dry wt at 330 umol/mol to 205 g/kg at 800 umol/mol. On each date, the daytime rate of starch accumulation combined over all CO2 treatments was 6 g/kg. Specific leaf weight increased significantly throughout the day both at 48 (0.64 g/m2/h) and 69 DAP (0.29 g/m2/h). Total Kjeldahl N (TKN) conc., expressed on a g/m2 basis, showed no change over the day. Total final dry wt increased 18, 34, and 54% at 450, 600 and 800 umol/mol, respectively. The TKN harvested per plant increased 25, 26 and 45% in the 450, 600 and 800 umol/mol CO2 treatments, respectively. Plants in the 450 umol/mol CO2 treatment partitioned more biomass to seed than the other CO2 treatments. With that exception, we saw no great differences among treatment partitioning at final harvest, and thus interpret the main effect of CO2 enrichment to be enhanced photoassimilation by soybean canopies while maintaining consistent allometric relationships of the plants.&>&2&e%_ZY[QRW&L29^3^Allen,S G^Idso,S B^Kimball,B A^1990^1^Interactive Effects of CO2 and Environment on Net Photosynthesis of Water-Lily^13^30^^81-88^^^^^^^^^^59^^^^^^^^^^^Nymphaea marliac/water lilyy6&r+3ɿ & GGr&>&2>s&M'C^57^Agric. Ecosystems Environ.r&>&22&&8\ t&M'^_ZY[XPQRVWU&@&|&D2&d&L&A^57^Water-lily (_Nymphaea marliac_) plants were grown out of doors in 570-L stock tanks contained in plastic-walled, open-topped CO2-enrichment chambers continuously supplied with either 640 or 340 (ambient) uL CO2/L air. Net photosynthesis (Pn) of water-lily leaves in each CO2 treatment was measured hourly between 0800 and 1600 h MST on 26 October and 10 and 24 November 1987. Air temperature and net solar radiation were measured at the same time. The 3 days on which Pn was measured provided an air temperature range of 10.3-33.2C and a net solar radiation range of 30-659 W/m2. Significant linear relationships were established between Pn and air temperature and Pn and net solar radiation for both CO2 treatments. Significant interactive effects of CO2 and air temperature and CO2 and net solar radiation were also found to affect Pn. In conditions generally unfavorable for Pn (low light and low temperature), there was no difference in Pn rate between the two CO2 treatments. In conditions that were favorable for Pn (high light and high temperature), however, Pn in the 640 uL CO2/L air treatment was as much as 60% greater than in the ambient CO2 treatment.t Zrs Z>Xs3]_^YPSUC30^4^Allen,S G^Idso,S B^Kimball,B A^Anderson,M G^1988^1^Relationship between Growth Rate and Net Photosynthesis of _Azolla_ in Ambient and Elevated CO2 Concentrations^13^20^^137-141^^^^^^^^^^62^^^^^^^^^^^Azolla pinnataa~F33ɋ^V3C^60^Agric. Ecosystems Environ.6F߹d dÉF_^ZY[XVWu23 uφ ++r r; A^60^_Azolla pinnata_ was grown out-of-doors at Phoenix, AZ, U.S.A. in open-topped plastic-walled chambers supplied with e ither 340 or 640 uL CO2/L air. Net photosynthesis and growth rate were measured weekly between September 1985 and May 1986 and a significant (P<0.01) positive correlation was established between these two parameters in both CO2 environments. Regression coefficients for the linear regression of growth rate onto net photosynthesis were not significantly different in the two CO2 environments, indicating that the rate of growth per unit of CO2 uptake is not influenced by an atmospheric C O2 concentration-environment interaction.F&FF tFF 7X7XÚ${Ú${ÚO${Ú31^3^Alpert,P^Warembourg,F R^Roy,J^1992^1^Transport of Carbon among Connected Ramets of _Eichhornia crassipes_ (Pontederiaceae) at Normal and High Levels of CO2^14^78^^1459-1466^^^^^^^^^^65^^^^^^^^^^^Eichhornia crassipes/water hyacinth/water hyacinth66u6r9S^[r t!"C266:|S^[rT^]_YZ[PSRU2666aC^63^Amer. J. Bot.&"]Z[XPQV&=t&|t&\&"${ ^YXPSQWU싏a&;MuEX&:Mu;A^63^The floating stoloniferous plant, _Eichhornia crassipes_, has high rates of productivity and rapidly invades new site+s. Because the transport of carbon among connected ramets in known to increase the growth of clonal plants, we asked whether there is intraclonal carbon transport in _E. Crassipes_. Because net photosynthesis of _E. Crassipes_ is significantly .higher at high levels of atmospheric CO2, we also asked if high CO2 can change patterns of carbon transport in ways that m<ight modify clonal growth. We exposed individual ramets within groups of connected ramets to 14-CO2 for 15-45 min and measured the distribution of 14-C in the group after 4 days of growth at 350, 700, 1,400, or 2,800 uL/L CO2. At 350 uL/L CO2, @a parent ramet exported approximately 10% of the 14-C that it assimilated to its first rooted offspring ramet. The offspriMng exported a similar percentage of the 14-C it assimilated toward the parent; two-thirds of this 14-C was retained by the parent, and one-third moved into new offspring of the parent. In all ramets, imported carbon moved into leaves as well asP roots. At the higher levels of CO2, the percentage of assimilated carbon exported from a parent ramet to the leaf blades ^of its first offspring was lower by half. High CO2 had little other effect on carbon transport. _E. crassipes_ maintains b idirectional transport of carbon between ramets even under uniform and favorable environmental conditions and when externabl CO2 levels are very high.LD0D~t!tu t t5*s =uoF]ZXSVb腚r.&6n"32^2^Alscher,G^Krug,H^1989^1^On-line Control of CO2 Enrichment in Protected Cultivation^15^248^^321-327^^^^^^^^^^68^^^^^^^^^^^lettuce/Lactuca sativaa L.]^_ZY[XPSQRWVU这s&>t,&M&&] 2&=&E t&E u &e|rStrr C^66^Act. Hort.}0&O &E't&E' uS&2&a [0rsF]^_ZY[XPWUr&;>s&e{%A^66^As a base for experiments on CO2 on-line control the CO2 fluxes in greenhouses are simulated and potential control st&rategies presented. Some approaches are tested, others outlined for discussion. Preliminary experiments with lettuce were 'performed with CO2 supply depending on wind velocity and irradiance. Additionally, intermittent CO2 application was tested(. Results indicate that the efficiency of CO2 enrichment varies relying on season and year. If planted in October cutting )off CO2 supply led to extended growth periods with increased energy demands. If planted in January no significant differen*ces in growing periods occurred between constant CO2 treatments, intermittent CO2 supply and cutting off due to wind velocity and irradiance, except differences to the control. Simulations for optimizing CO2 on-line control are in progress.33^1^Amthor,J S^1991^1^Respiration in a Future, Higher-CO2 World^16^14^^13-20^^^^^^^^^^711 tTdؾDu&E&M#C^69^Plant, Cell and EnvironmentHr~r: sF ]^_ZY[XRPWVU˷r觔r&6&D&t&t:ŷrsF.A^69^Apart from its impact on global warming, the annually increasing atmospheric [CO2] is of interest to plant scientists/ primarily because of its direct influence on photosynthesis and photorespiration in C3 species. But in addition, 'dark' r0espiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO2] independen1t of an increase in temperature. Literature pertaining to an impact of [CO2] on respiration rate is reviewed. With an incr2ease in [CO2], respiration rate is increased in some cases, but decreased in others. The effects of [CO2] on respiration r3ate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms rel4ate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) c5omposition of phytomass, (4) direct chemical interactions between CO2 and respiratory enzymes, (5) direct chemical interac6tions between CO2 and other cellular components, (6) dark CO2 fixation rate, and (7) ethylene biosynthesis rate. Because a7 range of (possibly interactive) effects exists, and present knowledge is limited, the impact of future [CO2] on respirati8on rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined.5 ƚe,sG*"P7 e,sG t[2 *3>et:6bt)F:34^3^Amthor,J S^Koch,G W^Bloom,A J^1992^1^CO2 Inhibits Respiration in Leaves of _Rumex crispus_ L^17^98^^757-760^^^^^^^^^^74^^^^^^^^^^^Rumex crispus/curly dockdock^_+rXr ^o]^ZY[XˉF SVWPR2@t<u23 t 2$6F_^,C^72^Plant Physiol.b& t̀u4: Nt @suFu^~[XPSRUbۀt.0.=A^72^Curly dock (_Rumex crispus_ L.) was grown from seed in a glasshouse at an ambient CO2 partial pressure of about 35 pa>scals. Apparent respiration rate (CO2 efflux in the dark) of expanded leaves was then measured at ambient CO2 partial pres?sure of 5 to 95 pascals. Calculated intercellular CO2 partial pressure was proportional to ambient CO2 partial pressure in@ these short term experiments. The CO2 level strongly affected apparent respiration rate: a doubling of the partial pressuAre of CO2 typically inhibited respiration by 25 to 30%, whereas a decrease in CO2 elicited a corresponding increase in res!Bpiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO2 (a byproduct o*f respiration) and some component(s) of heterotrophic metabolism is indicated.^_Y;w+PRVW363^VF-D35^4^Anderson,I H^Dons,C^Nilsen,S^Haugstad,M K^1985^1^Growth, Photosynthesis and Photorespiration of _Lemna gibba_: Respon0Ese to Variations in CO2 and O2 Concentrations and Photon Flux Density^18^6^^87-96^^^^^^^^^^77^^^^^^^^^^^Lemna gibba/duckwe3edd2F xd }2hZ-$d<(  D 6 _PSQRWV ;C^75^Photosynth. Res....&ˆFFFsvFVNF^rr^ Ffu8t2FvBtOfF6HA^75^Dry weight and Relative Growth Rate of _Lemna gibba_ were significantly increased by CO2 enrichment up to 6000 uL CO2AI/L. This high CO2 optimum for growth is probably due to the presence of nonfunctional stomata. The response to high CO2 waDJs less or absent following four days growth in 2% O2. The Leaf Area Ratio decreased in response to CO2 enrichment as a resGKult of an increase in dry weight per frond. Photosynthetic rate was increased by CO2 enrichment up to 1500 uL CO2/L duringL measurement, showing only small increases with further CO2 enrichment up to 5000 uL CO2/L at a photon flux density of 210JM umol/m2/s and small decreases at 2000 umol/m/s. The actual rate of photosynthesis of those plants cultivated at high CO2 XNlevels, however, was less than the air grown plants. The response of photosynthesis to O2 indicated that the enhancement oOf growth and photosynthesis by CO2 enrichment was a result of decreased photorespiration. Plants cultivated in low O2 prod[uced abnormal morphological features and after a short time showed a reduction in growth. t_:guZguRF?t;w uEFkQ36^1^Andersson,N E^1991^1^The Influence of Constant and Diurnally Changing CO2 Concentrations on Plant Growth and Development^19^66^^569-574^^^^^^^^^^80^^^^^^^^^^^Ficus benjamina/Rosa hybridaa&}D&=tv:/#:v*tmFC^78^J. Hort. Sci.^XPQRVWF~FFًLNLNLNLN^&2N&>N F&E'@tFVF m;VrTA^78^Plants of _Ficus benjamina_ and miniature rose (_Rosa hybrida_ cv. Red Minimo) were grown under four CO2 treatments. UTwo had constant CO2 levels (600 and 900 ppm) and the other two had diurnal changes in CO2 levels, one increasing from 600V to 1500 ppm and one decreasing from 1500 to 600 ppm, each in four steps of 300 ppm during the day-time. In all treatmentsW 900 ppm CO2 was maintained during the night when supplementary light was used, except in the treatment with constant 600 Xppm where 600 ppm was also continued throughout the night. Plant growth was monitored under both decreasing and increasingY natural daylength and irradiance. The tallest plants and greatest increment in height for _Ficus_ occurred with plants grZown under constant CO2 concentration at 900 ppm. In both experiments with miniature roses the number of flower buds was si[gnificantly increased under diurnally changing CO2 concentration or when the CO2 level was constant at 600 ppm compared with a constant 900 ppm. Time to flowering was decreased by constant CO2 at 900 as compared with the other treatments.I.:]37^6^Andre,M^Cotte,F^Gerbaud,A^Massimino,D^Massimino,J^Richaud,C^1989^1^Effect of CO2 and O2 on Development and Fructification of Wheat in Closed Systems^124^9^^(8)17-(8)28^^^^^^^^^^83^^^^^^^^^^^Triticum aestivum/wheat^^^^^^^um aestivum L./whme that physiological evidence indicates the CCM is approaching maximal activity. Glycolate DH activity in 24 hour air-ad`A^81^The cultivation of wheat (_Triticum aestivum_ L.) was performed in controlled environment chambers with the continuouas monitoring of photosynthesis, dark respiration, transpiration and main nutrient uptakes. A protocol in twin chambers wasb developed to compare the specific effects of low O2 and high CO2. Each parameter is able to influence photosynthesis but cdifferent effects are obtained in the development, fructification and seed production, because of the different effects ofd each parameter on the ratio of reductive to oxidative cycle of carbon. The first main conclusion is that low level of O2,e at the same rate of biomass production, strongly acts on the rate of ear appearance and on seed production. Ear appearancfe was delayed and seed production reduced with a low O2 treatment (about 4%). The O2 effect was not mainly due to the reprgession of the oxidative cycle. The high CO2 treatment (700 to 900 uL/L) delayed ear appearance by 4 days, but did not reduhce seed production. High CO2 treatment also reduced transpiration by 20%. Two hypotheses were proposed to explain the similarities and the difference in the O2 and CO2 effects on the growth of wheat.r &W&GN3zr rr rFF^r transfer and then declines to the original level within 48 hours. The decline in PGPase activity begins at about the tik38^2^Andre,M^Du Cloux,H^1993^1^Interaction of CO2 Enrichment and Water Limitations on Photosynthesis and Water-Use Efficie ncy in Wheat^20^31^^103-112^^^^^^^^^^86^^^^^^^^^^^wheat/Triticum aestivumm L.2&3ҁ~|u &L&L&;Lt&RC^84^Plant Physiol. Biochem.OIr`t\RQ&Gt&WNYZr;&G&g}r( t~\u%6:"6:nA^84^Wheat plants (_Triticum aestivum_ L. cv. Capitole) were grown in twin closed growth chambers with continuous monitoriong of CO2 and water exchanges. During the vegetative stage the effect of CO2 enrichment, from 330 to 660 uL/L, was studiedp under an irradiance of 660 uE/m2/s with an optimum watering. Comparisons were made with successive experiments in which d!qaily water supply was fixed to a fraction (0.62-0.5-0.25) of the maximal transpiration of previous experiments. In a well 1rwatered canopy, the doubling of CO2 decreased transpiration by only 8%. Water use efficiency was increased (factor 1.45) msainly by the stimulation of photosynthesis. Under restricted water supply, photosynthesis of plants was more limited than 4ttranspiration. The inhibition of photosynthesis and the increase of water use efficiency can be predicted by a simple diffAuusion model applied to the response curve of photosynthesis to CO2, measured on canopy in standard conditions of watering.v The main hypothesis is that the equivalent stomatal conductance is reduced proportionally to the water availability, withDwout closure by patching. Under enriched CO2, the same reduction of leaf surface by water limitation was observed. PhotosynRxthesis was less affected. Therefore, water use efficiency was again increased. Doubling CO2 concentration can compensate fyor water stress inhibition on CO2 assimilation. That model also predicts interactions of CO2 and water stress observed on Uzwater-use-efficiency which was increased by a factor up to 5 in comparison with well-watered plants in standard atmospheref. The implications of this study on global change models are discussed.&&G^SRYԡ[ tgb&y >^Ԛ(6: |39^3^Andre,M^Du Cloux,H^Richaud,C^1986^3^Wheat Response to CO2 Enrichment: CO2 Exchanges, Transpiration and Mineral Uptakej}s^Controlled Ecological Life Support System: CELLS '85 Workshop^AMES Research Center^Moffett Field, California^405-428^^^^x^^^1985 July 16-19, NASA Report TM88215^^^^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^^^^MacElroy,R^Martello,NV^Smernoff,D,DlXrq&GF&&G!_rY&ON&WVxXrBF t3ɋ^t XFFN^ t XFF t X|40^7^Andre,M^Ducloux,H^Richaud,C^Massimino,D^Daguenet,A^Massimino,J^Gerbaud,A^1987^1^Etude des Relations entre Photosynthese Respiration, Transpiration et Nutrition Minerale chez le Ble^124^7^^(4)105-(4)114^^^^^^^^^^90^^^^^^^^^^^wheat/Triticum aestivum^^^^^^^Triticum aestivum L.]Xse k xX^Y[F 7  F 7  >m^^^^^ Adv. Space Res. ',, &A^88^La croissance du Ble _Triticum aestivum_ a ete etudiee en environnement controle et ferme pendant une periode de 70 jours. Les echanges gazeux (Photosynthese, Respiration) hydriques (Transpiration) et al consommation en elements mineraux (Azote, Phosphore, Potassium) ont ete mesures en continu. On prsentera les relations dynamiques observees entre les differentes fonctions physiologiques, d'une part sous l'influence de la croissance et d'autre part en reponse a des modifications de l'environnement. L'influence de la teneur en CO2 pendant la croissance (teneur normale ou doublee) sera mise en evidence. In French.'-.---4,%%%%%%//,&l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(l(41^5^Andreeva,T F^Strogonova,L E^Voevudskaya,S Yu^Maevskaya,S N^Cherkanova,N N^1989^1^Effect of Enhanced CO2 Concentration on Photosynthesis, Carbohydrate and Nitrogen Metabolism, and Growth Processes in Mustard Plants^21^36^^40-48^^^^^^^^^^93^^^^^^^^^^^mustard/Brassica junceaa L.bC    ! V~C^91^Fiziol. Rast.U(sp10h12vsb3T&d@E%-12345X@PJL RDYMSG DISPLAY = "" %-12345Xerences*p1005Xwhich*p1132Xcan*p1210A^91^We investigated prolonged (8- to 10-day) influence of enhanced carbon dioxide content (0.03-0.05%) in the air on photosynthesis of mustard plants (_Brassica juncea_ L.), on their carbohydrate and nitrogen metabolism, and on the course of growth processes. Considerable attention is devoted to the question of the effect of leaf starch excess on the rate of photosynthesis. It is demonstrated that mustard plants in the vegetative phase of growth under conditions of enhanced CO2 concentration in the air exhibit higher pure productivity of photosynthesis and a higher rate of photosynthesis than in plants growing at normal CO2 content in the atmosphere. Increase of apparent photosynthesis is realized without supplementary synthesis of fraction I protein. Increase in the rate of photosynthesis is accompanied by intensification of nitrogen metabolism, increase of growth, and accumulation of biomass. An excess of assimilates in the form of starch accumulates in the chloroplasts (25% of leaf dry mass at 27/24). Starch content increases significantly in plants grown under conditions of reduced temperature compared with ones grown at a higher temperature (34.4% of leaf dry mass at 20/17 as compared with 20.1% at 32/27). It is concluded that high starch content in the leaves is not a cause of photosynthesis suppression. Decline of photosynthesis is observed only when the starch excess disturbs structure of the chloroplasts.))42^1^Apel,P^1989^1^Influence of CO2 on Stomatal Numbers^22^3^^72-74^^^^^^^^^^96^^^^^^^^^^^Phaseolus vulgaris/Vicia faba/Lycopersicon esculentum/Acer pseudoplatanus/Triticum aestivum/Hordeum vulgare/Secale cereale/Avena sativa/Zea mays/bean/broad bean/tomato/sycamore maple/wheat/barley/rye/oat/cornmaple/wheat/barley/rye/oat/cornTUPPPUUUUUUUUUUC^94^Biol. PlantarumUUUUUUUUUUUUUUUUUUUUUUUUUUUUEDDDDDDDDDEDDDDDDDDDTDDDDDDDDDDDDDDDDP A^94^From nine different plant species grown at 1500 cm3/m3 CO2 five responded with a significant increase in stomatal numbers per mm2 as compared with plants grown under normal air conditions. Within a collection of twelve french bean cultivars remarkable cultivar differences with regard to the CO2 enhancement effect on stomatal numbers was found. 43^1^Arnone,J A,III^1988^6^Photosynthesis, Carbon Allocation, and Nitrogen Fixation in Red Alder^^Yale University^^Doctora(l Dissertation^^^Dissertation Abstracts Vol.50:08-B, p.3244 (96 pp.)^^^^^^^98^^^^^^^^^^^Alnus rubra/red alderalderA^97^Research reported in the three sections of this dissertation addresses the problem of the effect of potentially high *carbon costs of nitrogen fixation by alder-Frankia symbioses on host plant biomass productivity. Effects of root nodulatio7n and nitrogen fixation on plant biomass productivity and allocation patterns were evaluated by growing inoculated and uninoculated red alder seedlings in atmospheres containing ambient (350 uL/L) and elevated (650 uL/L) levels of CO2, with and: without combined nitrogen (20 mg/L NH4NO3) supplied in modified N-free Hoagland's nutrient solution. Effect of nodulationD, CO2 enrichment, substrate nitrogen, and the feedback interaction on early seedling development and aboveground and belowground growth were also tested using the same plant material. Root:shoot ratios for plants in all treatments decreased oveHr the course of the experiment. This occurred more rapidly in nodulated plants and was attributed to more rapid attainmentU of balanced root:shoot growth. This and evidence supporting the hypothesis that whole plant internal carbon/nitrogen balance regulated aboveground and belowground growth is presented and discussed.X44^2^Arnone,J A,III^Gordon,J C^1990^1^Effect of Nodulation, Nitrogen Fixation and CO2 Enrichment on the Physiology, Growth` and Dry Mass Allocation of Seedlings of _Alnus rubra_ Bong^23^116^^55-66^^^^^^^^^^101^^^^^^^^^^^Alnus rubrara Bong.C^99^New Phytol.cA^99^Inoculated and uninoculated _Alnus rubra_ Bong. seedlings were grown for 47 days in atmospheres containing ambient (3t50 uL CO2/L) and elevated (650 uL CO2/L) levels of CO2, with and without combined nitrogen (20 mg/L) supplied as ammonium nitrate. Five plants from each treatment were harvested 15, 30, and 47 days after exposure to CO2 treatments began. Evidenwce for the presence of a positive feedback loop between nitrogen fixation and photosynthesis was observed in nodulated plants growing at elevated CO2. These plants had greater whole-plant photosynthesis and nitrogenase activity, leaf area and nitrogen content, as well as nodule and plant dry mass, relative to nodulated plants grown at ambient CO2 and non-nodulated plants grown at both CO2 levels. This feedback may be an important way in which the potential carbon drain of nitrogen fixation on the host plant could be compensated; increased nitrogen availability resulting in stimulated leaf area growth and whole-plant photosynthesis. The relative amount of dry mass allocated to below ground decreased for all seedlings over time, and the amount allocated above ground increased. This shift in allocation occurred slowly and at a constant rate in non-nodulated plants and more rapidly and abruptly when plants were nodulated. The proportion of dry mass allocated below ground was consistently greater in non-nodulated plants grown at high CO2. Dry mass partitioning among other organs was not directly affected by nodulation, CO2 enrichment, or other treatment interactions.45^1^Arp,W J^1991^1^Effects of Source-Sink Relations on Photosynthetic Acclimation to Elevated CO2^16^14^^869-875^^^^^^^^^C^102^Plant Cell Environ. 8GA^102^While photosynthesis of C3 plants is stimulated by an increase in the atmospheric CO2 concentration, photosynthetic capacity is often reduced after long-term exposure to elevated CO2. This reduction appears to be brought about by end product inhibition, resulting from an imbalance in the supply and demand of carbohydrates. A review of the literature revealed that the reduction of photosynthetic capacity in elevated CO2 was most pronounced when the increased supply of carbohydrates was combined with small sink size. The volume of pots in which plants were grown affected the sink size by restricting root growth. While plants grown in small pots had a reduced photosynthetic capacity, plants grown in the field showed no reduction or an increase in this capacity. Pot volume also determined the effect of elevated CO2 on the root:shoot ratio--the root:shoot ratio increased when root growth was not restricted and decreased in plants grown in small pots. The data presented in this paper suggest that plants growing in the field will maintain a high photosynthetic capacity as the atmospheric CO2 level continues to rise.    ^10404     46^1^Arp,WJ^1991^6^Vegetation of a North American Salt Marsh and Elevated Atmospheric Carbon Dioxide^^Centrale Huisdrukkerij Vrije Universiteit, Amsterdam^^Doctoral Dissertation^^^^^^^^^^^^^^^^^^^^^Distichlis spicata/Spartina patens/Scirpus olneyi^^^^^eyi        47^2^Arp,W J^Drake,B G^1991^1^Increased Photosynthetic Capacity of _Scirpus olneyi_ after 4 Years of Exposure to Elevated CO2^16^14^^1003-1006^^^^^^^^^^108^^^^^^^^^^^sedge/Scirpus olneyiyi C^106^Plant Cell Environ. A^106^While a short-term exposure to elevated atmospheric CO2 induces a large increase in photosynthesis in many plants, long-term growth in elevated CO2 often results in a smaller increase due to reduced photosynthetic capacity. In this study,  it was shown that, for a wild C3 species growing in its natural environment and exposed to elevated CO2 for four growing (seasons, the photosynthetic capacity has actually increased by 31%. An increase in photosynthetic capacity has been observ +ed in other species growing in the field, which suggests that photosynthesis of certain field grown plants will continue t /o respond to elevated levels of atmospheric CO2.a d h? 548^5^Arp,W J^Drake,B G^Pockman,W T^Curtis,P S^Whigham,D F^1993^1^Interactions between C3 and C4 Salt Marsh Plant Species d 9uring Four Years of Exposure to Elevated Atmospheric CO2^123^104/105^^133-143^^^^^^^^^^111^^^^^^^^^^^Spartina patens/Scirp =us olneyi/Distichlis spicata^^^^^&s4&s) ي54t "k)9 &s43kean variety was more promoted by CO2 enrichment than by NO3-N application, while that of the wild one was enhanced by NO3- @A^109^Elevated atmospheric CO2 is known to stimulate photosynthesis and growth of plants with the C3 pathway but less of p Jlants with the C4 pathway. An increase in the CO2 concentration can therefore be expected to change the competitive interactions between C3 and C4 species. The effect of long term exposure to elevated CO2 (ambient CO2 concentration + 340 umol C NO2/mol) on a salt marsh vegetation with both C3 and C4 species was investigated. Elevated CO2 increased the biomass of the W C3 sedge _Scirpus olneyi_ growing in a pure stand, while the biomass of the C4 grass _Spartina patens_ in a monospecific Zcommunity was not affected. In the mixed C3/C4 community the C3 sedge showed a very large relative increase in biomass in elevated CO2 while the biomass of the C4 species declined. The C4 grass _Spartina patens_ dominated the higher areas of th ]e salt marsh, while the C3 sedge _Scirpus olneyi_ was most abundant at the lower elevations, and the mixed community occup jied intermediate elevations. _Scirpus_ growth may have been restricted by drought and salt stress at the higher elevations, while _Spartina_ growth at the lower elevations may be affected by the higher frequency of flooding. Elevated CO2 may af mfect the species distribution in the salt marsh if it allows _Scirpus_ to grow at higher elevations where it in turn may a vffect the growth of _Spartina_.is required $ Error: 80286 or higher CPU is required $ 49^1^Artus,N N^1990^1^Two Mutants of _Arabidopsis thaliana_ That Become Chlorotic in Atmospheres Enriched with CO2^16^13^^ y575-580^^^^^^^^^^114^^^^^^^^^^^Arabidopsis thalianana L.2꤀DF>?a꤀DpF>?꤀D C^112^Plant Cell Environ.DWPP^WWP^#d":ffp d#d:ZA^112^Two nonallelic, nuclear recessive mutants of _Arabidopsis thaliana_ (L.) Heynh. which become chlorotic when grown in  an atmosphere enriched to 20,000 cm3 CO2/m3 have been isolated. For one of the mutants, chlorosis begins at the veins and  gradually spreads to the interveinal regions. A minimum photon flux density of ca 50 umol/m2/s is required for this response. For the other mutant, the yellowing is independent of the light intensity and begins at the basal regions of the leav es and spreads to the tips. The injurious effects of CO2 seem to be restricted to photosynthetic tissues, since root elong ation and callus growth were not inhibited by a high atmospheric CO2 concentration for either mutant. Neither mutant became chlorotic in a low O2 atmosphere that suppressed photorespiration as effectively as the elevated CO2 does. Thus, the mut ations do not impose a requirement for photorespiration. The possibilities that the high CO2-sensitive phenotypes are caus ed by an effect of CO2 in stomata, on ethylene synthesis, or on mineral uptake are discussed but are considered unlikely.50^3^Ashenden,T W^Baxter,R^Rafarel,C R^1992^1^An Inexpensive System for Exposing Plants in the Field to Elevated Concentra tions of CO2^16^15^^365-372^^^^^^^^^^11717SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS C^115^Plant Cell Environ.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS A^115^An inexpensive, potentially mobile field exposure system is described which may be easily constructed by a small wor kshop. It may be operated as an open-top with a frustum or covered with a polycarbonate 'lid'. The system is cost-effective for CO2 exposure work because the small size allows provision of CO2-enriched atmospheres over prolonged periods at rela tively low cost. A preliminary assessment of the chambers has been made and concentrations can be maintained at +/- 6% for  a target atmosphere of 680 cm3/m3 CO2 under normal operating conditions. Other chamber environmental conditions are reported.SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS            ! " # % & ) * + , - . 0 1 2 3 4 7 ; @  E F G H J K L M N O Q R S T V W X Y Z [ \ ] ^ _ a b c d e f g h j k l m n o p q r v w x y z { | } ~   51^1^Aston,A R^1984^1^The Effect of Doubling Atmospheric CO2 on Streamflow: a Simulation^24^67^^273-280^^^^^^^^^^1200t C^118^J. Hydrol. &Yt 8r>u&]&Ùt+ A^118^There is a potential for atmospheric CO2 to rise four- or six-fold, and at some time in the foreseeable future a dou bling of stomatal resistance seems, on present evidence, to be inevitable. A distributed deterministic process model was used to simulate the effects of changed stomatal resistance on streamflow of a 5-ha experimental catchment and a large (417  km2) water-supply area. The results indicated that we can expect streamflow to increase from 40 to 90% as a consequence of doubling of atmospheric CO2 concentration.Y]&D2 W> uv&t&| uuK6H]3&t t@[W 52^1^Austin,M P^1992^1^Modelling the Environmental Niche of Plants: Implications for Plant Community Response to Elevated CO2 Levels^25^40^^615-630^^^^^^^^^^123^^^^^^^^^^^Eucalyptus fastigatataK<}EE&&dFV&&`FV C^121^Aust. J. Bot.^NV;u;rEEEE3F^NV;u;֋NV;u;֋F^;u; u  A^121^No simple natural gradients in CO2 concentration exist for testing predictions about changes in plant communities in  response to elevated CO2. However indirect effects of CO2 via temperature increases can be tested by reference to natural  analogues. Physiologists, vegetation modellers of climate change and community ecologists assume very different temperature responses for plants. Physiologists often assume a skewed non-monotonic curve with a tail towards low temperatures, for est modellers using FORET type models, a symmetric curve, and community ecologists a skewed response with a tail towards h #igh temperatures. These assumptions are reviewed in relation to niche theory, and recent propositions concerning the continuum concept. Confusion exists between the different approaches over the shape of response curves to temperature. Distinctions need to be made between responses due to growth (physiological response), potential fitness (fundamental niche) and observed performance (realised niche). These types of response should be quantified and related to each other if process-models are to be tested for predictive success by reference to naturally occurring communities and temperature gradients. An / example of a statistical method for quantifying the realised environmental niche response of a species to temperature is provided. It is based on generalised linear modelling (GLM) of presence/absence data on _Eucalyptus fastigata_ for 8377 si 3tes in southern New South Wales, Australia. Seven environmental variables or factors are considered: mean annual temperatu >re, mean annual rainfall, mean monthly solar radiation, topographic position, rainfall seasonality, lithology, and soil; nutrient status. The temperature response is modelled by a _Beta_-function, log _y + a + alpha_ log _(t - a) + sigma_ log _ A(b - t)_, where _t_ is temperature and letters are parameters. The probability of occurrence is shown to be a skewed funct Jion of mean annual temperature. Any process-models of climate change for vegetation incorporating temperature changes due to elevated CO2 must be capable of generating such realised environmental niche responses for species.YPSQRVWUt M53^1^Badger,M^1992^1^Manipulating Agricultural Plants for a Future High CO2 Environment^25^40^^421-429^^^^^^^^^^12626 P C^124^Aust. J. Bot.&ur N?&^XW>~;6w*r&2r _ A^124^This paper discusses the potential ways in which C3 plant performance may benefit from a future high-CO2 environment!. These include increases in the efficiencies for light, nitrogen and water utilisation, particularly at elevated temperat b"ures, resulting from the improvement which will occur in the performance of the primary carboxylating enzyme, Rubisco. How n#ever, while growth experiments at elevated CO2 indicate that C3 plants show stimulation of dry matter accumulation, the po$tential gains are greatly ameliorated by a redistribution of plant resources. This primarily occurs via a reduction in the q% leaf area ratio which offsets increases in the net assimilation rate. In addition, there may be an overcommitment of nitr y&ogen in key photosynthetic components such as Rubisco and the thylakoid electron transport system. It is concluded that pl'ants may not be genetically adapted to optimise their growth and performance at elevated CO2 and that consideration should }( be given to exploring avenues for manipulating plants for more optimal responses. Targets for improvement of growth at el )evated CO2 include (1) altering source-sink relations; (2) improving the redistribution of nitrogen between the photosynth*etic machinery and the rest of the plant; and (3) changing the response of stomata to CO2 and humidity to increase water-u se efficiency even further than is currently predicted.tƀt҃ǀt t t t 54^1^Baille,A^1989^1^Greenhouse Microclimate and Its Management in Mild Winter Climates^15^246^^23-36^^28Xr uC^127^Act. Hort.\&Q9r J9rK&2Q &79rY5O&r9rr9rr֊9rϊ8rr .55^2^Bailly,J^Coleman,J R^1988^1^Effect of CO2 Concentration on Protein Biosynthesis and Carbonic Anhydrase Expression in _Chlamydomonas reinhardtii_^17^87^^833-840^^^^^^^^^^131^^^^^^^^^^^Chlamydomonas reinhardtiiiidu&^_X. ,C^129^Plant Physiol.rdۉsW3PWPryd3ҹd4Xך؇6F_ tы:_QrFw33ɋ&:w 1A^129^The effect of external inorganic carbon (Ci) concentrations on protein biosynthesis and carbonic anhydrase (CA) mRNA2 abundance were examined in the eukaryotic alga _Chlamydomonas reinhardtii_. Transfer of high CO2 (5%) grown algae to air 3levels of CO2 resulted in the transitory synthesis of two polypeptides of approximately 49,000 and 52,000 daltons as well 4as prolonged synthesis and accumulation of the 37,000 dalton CA monomer and an unidentified 20,000 dalton polypeptide. The5 gene coding for carbonic anhydrase was isolated from a genomic expression library and subjected to restriction endonuclea 6se analysis. Southern blot analysis of chromosomal DNA indicates that only a single copy of the gene is present. The 2.5 k 7ilobase DNA fragment hybridizes specifically to a 1.4 kilobase transcript in RNA isolated from air-grown cells and from ce 8lls grown on 5% CO2 that have been exposed to air levels of CO2. Maximum mRNA abundance was observed after 1 to 3 hours of 9 exposure to air. Transfer of air-grown cells to a high CO2 environment resulted in the elimination of the CA transcript a:fter 60 minutes of exposure. Changes in CA transcript abundance in response to external Ci concentrations occurred in the presence or absence of light. & tG4&_&&c&[ }r4Fr ^r$s^r&>&F^2 <56^2^Baker,R G E^Boatman,D J^1990^1^Some Effects of Nitrogen, Phosphorus, Potassium and Carbon Dioxide Concentration on th=e Morphology and Vegetative Reproduction of _Sphagnum cuspidatum_ Ehrh^23^116^^604-611^^^^^^^^^^134^^^^^^^^^^^Sphagnum cus pidatumum Ehrh.ZY[XSRQU&DžOv&t%&%N.P&%&!Y&Q&!U&tD&!vP&+Uy&!& /C^132^New Phytol.&UY&Q&U&!v]YZ[PSQRVW&6&[ oskF^Nc&E%t@A^132^Five experiments are described which were designed to investigate the effects of varying the concentrations of nitra Ate, phosphate, potassium and carbon dioxide in the culture solution on the morphology and vegetative reproduction of _Spha Bgnum cuspidatum_ Ehrh. The plants were grown axenically from spores sown on agar containing inorganic salts and then transCferred to aqueous culture solutions through which air containing enhanced concentrations of carbon dioxide was passed. In Dthree of the experiments the plants were grown in a balanced inorganic salt solution at various dilutions and in two of th Eese the concentration of carbon dioxide in the gas bubbled through the solution was varied. The concentrations of nitrogenF, phosphorus and potassium were varied independently and in combination in the remaining experiments while the concentrati Gon of carbon dioxide was kept constant. In some of the experiments the minimum concentrations of nitrogen and potassium su Hpplied were considerably below the minimum average concentrations recorded in rain but the minimum concentration of phosph Iorus supplied was within the upper part of the range recorded in rain. Within the ranges supplied the concentrations of al Jl three elements and of carbon dioxide affected interfascicle length and vegetative reproduction (innovation formation) bu t it was concluded that the element limiting innovation formation in natural conditions is phosphorus.2~FU&E0 %L57^3^Baldocchi,D D^White,R^Johnston,J W^1989^1^A Wind Tunnel Study to Design Large, Open-top Chambers for Whole-tree Pollu 'tant Exposure Experiments^27^39^^549-1556^^^^^^^^^^13737F։F@FʉF΋3FƋ1FvĿc$6F~6F6 3>C^135^JapcaFF-]6F^3&E&E&E&E &E&E"tQ!&E(&E*%&E,&E._ZY[XPSQRVW F 6OA^135^A wind tunnel study was conducted to determine the optimal design features of a large, open-top chamber, as needed f 8Por pollution exposure studies on mature trees. An optimally-designed, open-top chamber must minimize the incursion of ambi GQent air through its opening and maintain a uniform treatment concentration throughout the chamber. The design features of Rinterest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be m JSounted on top of a model chamber. Design specifications depend on the turbulence regime about the chamber, which is influe ZTnced by the nature of the surrounding vegetation. Consequently, our investigation was performed on scale-model, open-top cUhambers in a wind tunnel populated with a model coniferous forest. Turbulence measurements demonstrated the similarity bet ]Vween the turbulence regime of the model and a natural forest. A hydrocarbon tracer was injected into the wind tunnel flow kWto characterize chamber performance. The main design features of open-top chambers are the velocity of air exiting throughX the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit nYvelocities increase, the proportion of eddies with sufficient force to penetrate into the chamber decrease. Therefore, for qZ equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambien t[t air incursions. Almost total exclusion of ambient air is achieved as the exit velocity of the air exceeds the magnitude \of one standard deviation of the vertical wind velocity measured at the chamber top. The incursion of ambient air is also w]reduced when the diameter of the chamber opening is smaller than the characteristic length scale of the turbulence, a meas |^ure of mean eddy size. Frusta deflect air flow over the chamber. Three prototypes, with 30-, 45- and 60-degree angles were _ tested. A 30-degree frustum slightly improves the performance of the chamber and is more effective in preventing ambient `air from entraining into the chamber opening than frusta with either a 45- or 60-degree angle. A flatter frustum allows fo ar a smoother transition in the wind velocity streamline and is less apt to cause wake turbulence, as is the case with stee bper frusta. Knowledge of the turbulence characteristics of plant canopies are readily available in the literature and can caid scientists and engineers in designing the optimal chamber and frusta dimensions for their particular application. Ther efore, the empirical approach to chamber design can be avoided, and substantial savings can be realized.[uS^v58^2^Ball,M C^Munns,R^1992^1^Plant Responses to Salinity under Elevated Atmospheric Concentrations of CO2^25^40^^515-525^^ MC^138^Aust. J. Bot.QNv^Ft6FN6FFvY[XPSQRV6@t%KKwtMt c gA^138^This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of hhalophytic and non-halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be iregulated to protect sensitive metabolic sites from salt toxicity. Salt-tolerant species exclude most of the salt from the j transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concent krations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt s ltorage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and th me expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one nof the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies co oupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CpO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevat qed CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake r is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient ands elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in t both C3 and C4 non-halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust t uo environmental factors affecting the availability of water and ions at the roots (salinity) and those affecting carbon gain in relation to water loss at the leaves (atmospheric concentrations of water vapour and carbon dioxide).DF&DF& ^^^^^^^^14040F{s& 2& ؋&^&\^FlOriF22賱rX؋&&tt 2&&2&e'_ZYSQRWr$3ɿ & GGr&>&2&e%_ZY[QRW&L {A^141^Australia produced $2.7 billion worth of forest products in 1983-84 but a further $1.3 billion worth, principally so |ftwood, were imported. Because of this ever increasing demand for softwood, there is a move away from utilization of nativ }e hardwoods and by 2020 AD, when the atmospheric CO2 concentration is likely to be greater than 450 ppmv, 75% of forest pr~oducts are projected to come from coniferous plantations. This move towards _Pinus radiata_ is a result of both demand for  softwood and lack of indepth investigations of the potential of Australian native species, particularly eucalypts, for plantation forestry. _Pinus radiata_ is the major plantation softwood in southern Australia and is presently grown at sites where phosphorus deficiency and repeated episodes of drought are common. Consequently, we are investigating the growth res ,ponse of pines to elevated CO2 at a range of phosphorus and water levels. When phosphorus was adequate, doubling CO2 conce /ntration more than doubled the rate of photosynthesis and increased the total plant dry weight by about 40%. However, ther Pe was no response when phosphorus was deficient. In contrast, there was a slightly higher response under simulated drought conditions. A further possible effect of rising CO2 levels is that the climatic range of _P. radiata_ may be altered due Tto a reduction in water use or an increase in the drought tolerance of the trees. We found that CO2 enrichment did not aff dect either of these factors but the water-use efficiency was increased when phosphorus was adequate. All families of _P. radiata_ do not respond to CO2 enrichment in the same manner. In a study investigating the response of four families to ele gvated CO2 at two phosphorus levels, we have identified a considerable variation between the families in their response to pCO2 and phosphorus. To date our studies have indicated that the projected increase in atmospheric CO2 levels is likely to have a significant influence on the productivity of Australia's _P. radiata_ plantations. But this will only occur if phos tphorus fertilization is adequate. If the rise in CO2 results in climatic change the range of _P. radiata_ may be even furt her restricted because there will be no concomitant decrease in water use or increase in drought tolerance. There is an urgent need for complementary studies of the response of Australian native species to elevated CO2 at realistic levels of ph osphorus and water to enable more accurate prediction of the productivity and water use of Australian native forests and e ucalyptus plantations.]ZY[_^F&FF tFF 7X7XÚ${Ú${ÚO${Ú%;60^2^Baron,J J^Gorski,S F^1986^1^Response of Eggplant to a Root Environment Enriched with CO2^28^21^^495-498^^^^^^^^^^2058 eC^143^HortSci.t &\?2A'&L&8t&W326 rJ& rA&9s"s5ʋF3${r)&F |rv&<3 62^2^Barson,M M^Gifford,R M^1990^3^Carbon Dioxide Sinks: The Potential Role of Tree Planting in Australia^Greenhouse and Energy^CSIRO^Australia^433-443^^^^^^^^^^149^^^^^^^^^^^^^^^^^^^^^Swain,DJ9;5_^Y[ˀ>@ t>@ u A^148^Reforestation has been suggested as a possible policy option at several recent international 'greenhouse effect' for ums. The issue of deforestation/reforestation may be the subject of a protocol for which detailed arrangements will be developed following the establishment of a non-obligatory Framework Convention on Climate Change in the early 1990's. Althoug h forestry cannot in principle offer a permanent solution to continuous emission of CO2 from fossil fuel burning, its expa nsion could assist in slowing down net emissions. This would 'buy time' to reduce rates of CO2 emission and to develop strategies to adapt to global atmospheric and climate change. A simple model is developed to explore the dynamics of carbon s equestration by new forest plantations. The areal extent of land suitable for reforestation is also examined. It is concluded from one optimistic scenario that a program of planting 40,000 ha/y of new forest onto non-forested land could, after 20 y absorb about 5-12 Mt (C) p.a. (7-17 per cent 1987-88 total Australian emissions) as long as planting at that rate continued.F&9&uHr~r: sF ]^_ZY[XRPWVU˷r觔r&6&D&t&t:ŷrsFA^151^Increasing atmospheric carbon dioxide concentrations present a novel resource condition for plant communities. In or der to understand and predict how plant community structure and function may be altered in a high CO2 world, we need to understand how interactions among neighboring plants within a community will alter the growth and reproduction of component species. Because CO2 is readily diffusible, plants have little influence on the CO2 acquisition of their neighbors, except . within particularly dense canopies. Thus, plants seldom compete directly for CO2. Rather, CO2 availability is likely to alter plant-plant interactions indirectly through its effects on plant growth and competition for other resources. As a con 2sequence, competitive outcome under elevated CO2 atmospheres within even simple systems is not easy to predict. For example, under some conditions, C4 species in competitive assemblages have improved competitive ability relative to C3 competito 5rs as a result of CO2 enrichment, contrary to expectations based on their photosynthetic pathways. It is now clear that in Bdividually grown plants can differ substantially from those within mono- or multispecific stands in response to CO2 enrichment. At present, our understanding of how stands of interacting plants modify the availability of CO2 and other resources E is incomplete. We urgently need information about how elevated CO2 atmospheres influence stand formation and population d Synamics, specifically with regard to the identities, numbers, sizes and reproductive fitnesses of individuals within singl Ue and multiple species stands, if we are to make multi-generational predictions concerning the fate of populations and communities in an elevated CO2 world.t̀u4: Nt @suFu^~[XPSRUbۀt.0. Y353r^^]Z[XˉFV&<uFQr&<t&<u r E4:^V&<uF#r&<t&<u `r 4:^65^2^Bazzaz,F A^Garbutt,K^1988^1^The Response of Annuals in Competitive Neighborhoods: Effects of Elevated CO2^2^69^^937-9 \46^^^^^^^^^^156^^^^^^^^^^^Ambrosia artemisiifolia/Abutilon theophrasti/Amaranthus retroflexus/Setaria faberiiSetaria fabe erii Herm.^_ZY[XPQVWUd&>u6 hA^154^Four members of an annual community were used to investigate the effects of changing neighborhood complexity and inc xreased CO2 concentration on competitive outcome. Plants were grown in monoculture and in all possible combinations of two, three, and four species in CO2-controlled growth chambers at CO2 concentrations of 350, 500, and 700 uL/L with ample mois {ture and high light. Species responded differently to enhanced CO2 level. Some species (e.g., _Abutilon theophrasti_) had increased biomass with increasing CO2, while others (e.g., _Amaranthus retroflexus_) had decreased biomass with increasing CO2 concentration. In mixtures, species tended to interact strongly, and, in some cases, the interaction canceled out the  effects of CO2. Furthermore, there were clear differences in species behavior in different competitive neighbors. In gene ral, competitive arrays that had C3 species depressed the response of C4 species, especially _Amaranthus_. _Ambrosia artemisiifolia_ was the strongest competitor in the assemblage. Strong statistical interactions between CO2 and the identity of  the competing species in mixtures were found to be primarily due to the as yet unexplained response of plants with CO2 at  500 uL/L. The potential effects of CO2 on community structure could be profound, particularly at the intermediate levels of CO2 that are predicted to be reached during the first half of the next century.PSQV &}tGt)< u!&2&A 66^1^Bazzaz,F A^1990^1^The Response of Natural Ecosystems to the Rising Global CO2 Levels^30^21^^167-196^^58_rtDޚ C^157^Ann. Rev. Ecol. Syst.dPSQRVWtE&4u ?u<6}t~tGXv3ҋF&;uGG t uB:67^4^Bazzaz,F A^Ackerly,D D^Woodward,F I^Rochefort,L^1992^1^CO2 Enrichment and Dependence of Reproduction on Density in an Annual Plant and a Simulation of Its Population Dynamics^31^80^^643-651^^^^^^^^^^161^^^^^^^^^^^Abutilon theophrasti^^^^^C^159^J. Ecol.Q t t:YXPW&2&E:G _XPSQVW<f&}D&=tv:/#:v*t A^159^1. Populations of an annual plant, _Abutilon theophrasti_, were grown at four densities (100, 500, 1500 and 4000/m2)  and two CO2 concentrations (350 and 700 uL/L) to examine the influence of CO2 environment on density-dependent patterns o f demography and reproduction. Variables measured included survivorship, proportion of plants flowering and fruiting, numb er of fruiting individuals, number of seeds per individual, total seed production per population, mean seed mass, and germination of seeds produced in each environment. 2. All variables, except the number of fruiting individuals, declined with increasing density, and at the highest density no individuals set seed. The number of fruiting individuals was highest at a density of 500/m2. In the elevated CO2 environment, survivorship was significantly reduced but the proportion of plants flowering and fruiting and the number of fruiting individuals in each population all increased. Total population seed prod uction was higher in the elevated CO2 environment at all densities, although the differences were not significant. Significant effects of CO2 concentration were observed only for population-level variables, but not for mean individual fecundity  or seed size. Seed germination declined with increasing maternal density, and no germination was recorded for seeds produ ced at 1500 /m2. 3. Simple models of population dynamics, utilizing difference equations, were constructed to examine potential population-level consequences of these density and CO2 effects. In the absence of a persistent seed pool, the simula ted populations exhibited damped or stable oscillations under low germination values, but displayed non-cyclic ('chaotic') oscillations or went extinct for higher germination due to the complete failure of seed-set at high density. Because of its higher fecundity, the elevated-CO2 population generally exhibited greater oscillations, and the critical germination value at which the simulated populations went extinct was much lower for the elevated-CO2 than for the ambient-CO2 population.ˉN rB_r=&G &8r*&&3Ћ"r3 F&8Et &MN&M0&&O&G{r68^3^Bazzaz,F A^Coleman,J S^Morse,S R^1990^1^Growth Responses of Seven Major Co-occurring Tree Species of the Northeastern  United States to Elevated CO2^32^20^^1479-1484^^^^^^^^^^164^^^^^^^^^^^American beech/Fagus grandifolia/paper birch/Betula papyrifera/black cherry/Prunus serotina/white pine/Pinus strobus/red maple/Acer rubrum/sugar maple/Acer saccharum/eastern hemlock/Tsuga canadensis./eastern hemlock/Tsuga canadensis (L.) Carr.2ˉN0urI rA&G &C^162^Can. J. For. Res.3 F&8Et A&M&M0&&O&G$r &W&GN3zr rr rFFA^162^We examined how elevated CO2 affected the growth of seven co-occurring tree species: American beech (_Fagus grandifolia_ Ehrh.), paper birch (_Betula papyrifera_ Marsh.), black cherry (_Prunus serotina_ Ehrh.), white pine (_Pinus strobus_ L.), red maple (_Acer rubrum_ L.), sugar maple (_Acer saccharum_ Marsh.), and eastern hemlock (_Tsuga canadensis_ (L.) Carr.). We also tested whether the degree of shade tolerance of species and the age of seedlings affected plant responses to enhanced CO2 levels. Seedlings that were at least 1 year old, for all species except beech, were removed while dormant fr%om Harvard Forest, Petersham, Massachusetts. Seeds of red maple and paper birch were obtained from parent trees at Harvard& Forest, and seeds of American beech were obtained from a population of beeches in Nova Scotia. Seedlings and transplants were grown in one of four plant growth chambers for 60 d (beech, paper birch, red maple, black cherry) or 100 d (white pin*e, hemlock, sugar maple) under CO2 levels of 400 or 700 uL/L. Plants were then harvested for biomass and growth determinat2ions. The results showed that the biomass of beech, paper birch, black cherry, sugar maple, and hemlock significantly increased in elevated CO2, but the biomass of red maple and white pine only marginally increased in these conditions. Furtherm5ore, there were large differences in the magnitude of growth enhancement by increased levels of CO2 between species, so it; seems reasonable to predict that one consequence of rising levels of CO2 may be to increase the competitive ability of some species relative to others. Additionally, the three species exhibiting the largest increase in growth with increased CO>2 concentrations were the shade-tolerant species (i.e., beech, sugar maple, and hemlock). Thus, elevated CO2 levels may enHhance the growth of relatively shade-tolerant forest trees to a greater extent than growth of shade-intolerant trees, at least under the light and nutrient conditions of this experiment. We found no evidence to suggest that the age of tree seedKlings greatly affected their response to elevated CO2 concentration.6&&G^SRYԡ[ tgb&y >^Ԛ(6: S69^2^Bazzaz,F A^Fajer,E D^1992^1^Plant Life in CO2-Rich World^33^266^^68-74^^66SRb&y >^Ԛ(6: u eԋ_CC^165^Sci. Amer.u_ԋw+e+my+e+mԋw+_+kZ[nNV t~hZuNc+_@Fa+e@FW70^3^Bazzaz,F A^Garbutt,K^Williams,W E^1985^3^Effect of Increased Atmospheric Carbon Dioxide Concentration on Plant Communfities^Direct Effects of Increasing Carbon Dioxide on Vegetation^U.S. Dept. of Energy, Carbon Dioxide Research Division^Washington, D.C.^155-204^^^^^^^DOE/ER-0238^^^^^^^^^^^^^^^^^^^^^^^^Strain,BR^Cure,J D @^~t ;c u>i uc i71^3^Bazzaz,F A^Garbutt,K^Williams,W E^1985^5^The Effect of Elevated Atmospheric CO2 on Plant Communities^NTIS, U.S. Dept.q of Commerce, Springfield, Virginia^^^^^^^^^^^^^^^^^^^^^^^^^^TR023 in Yellow Report Series^DOE/EV/04329-5^Dept. of Energy, Carbon Dioxide Research Division^de Research Division^ ',, &t72^4^Bazzaz,F A^Garbutt,K^Reekie,E G^Williams,W E^1989^1^Using Growth Analysis to Interpret Competition between a C3 and a C4 Annual under Ambient and Elevated CO2^34^79^^223-235^^^^^^^^^^171^^^^^^^^^^^Abutilon theophrasti/Amaranthus retroflexusroflexus L.  (((0)9))))))(((((())))")*-*Y*L)&&&&&&&&&&'<'C^169^Oecologiap([(B(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p(p( /.,,,,, , , , , ,,,A^169^Detailed growth analysis in conjunction with information on leaf display and nitrogen uptake was used to interpret c ompetition between _Abutilon theophrasti_, a C3 annual, and _Amaranthus retroflexus_, a C4 annual, under ambient (350 uL/L ) and two levels of elevated (500 and 700 uL/L) CO2. Plants were grown both individually and in competition with each othe r. Competition caused a reduction in growth in both species, but for different reasons. In _Abutilon_, decreases in leaf a rea ratio (LAR) were responsible, whereas decreased unit leaf rate (ULR) was involved in the case of _Amaranthus_. Mean ca nopy height was lower in _Amaranthus_ than _Abutilon_ which may explain the low ULR of _Amaranthus_ in competition. The decrease in LAR of _Abutilon_ was associated with an increase in root:shoot ratio implying that _Abutilon_ was limited by competition for below ground resources. The root:shoot ratio of _Amaranthus_ actually decreased with competition, and _Amaranthus_ had a much higher rate of nitrogen uptake per unit of root than did _Abutilon_. These latter results suggest that _Amaranthus_ was better able to compete for below ground resources than _Abutilon_. Although the growth of both species was reduced by competition, generally speaking, the growth of _Amaranthus_ was reduced to a greater extent than that of _Abutilon_. Regression analysis suggests that the success of _Abutilon_ in competition was due to its larger starting capital (seed size) which gave it an early advantage over _Amaranthus_. Elevated CO2 had a positive effect upon biomass in _Amaranthus_, and to a lesser extent, _Abutilon_. These effects were limited to the early part of the experiment in the case of the individually grown plants, however. Only _Amaranthus_ exhibited a significant increase in relative growth rate (RGR). In spite of the transitory effect of CO2 upon size in individually grown plants, level of CO2 did effect final biomass of competitively grown plants. _Abutilon_ grown in competition with _Amaranthus_ had a greater final biomass than _Amaranthus_ at ambient CO2 levels, but this difference disappeared to a large extent at elevated CO2. The high RGR of _Amaranthus_ at elevated CO2 levels allowed it to overcome the difference in initial size between the two species.ddd' 73^1^Beer,S^1986^3^The Fixation of Inorganic Carbon in Plant Cells^Physiology, Yield, and Economics^CRC Press, Inc.^Boca Raton, Florida^3-11^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^173^^^^^^^^^^^^^^^^^^^^^Enoch,H^Kimball,B AB AA^172^The initial fixation of atmospheric inorganic carbon (CO2) in plant cells is carried out via either the C3 or C4 pathway. The first step of the C3 pathway is the fixation of CO2 by a five-carbon compound to yield two molecules of PGA (a three-carbon compound). PGA is subsequently reduced to form sugars. In the so-called C3 plants, this is the only pathway fo r incorporation of CO2. The enzyme (RuBPcase) catalyzing CO2 fixation in the C3 pathway may also act as an oxygenase. When! doing so, glycolate (a two-carbon compound) is formed together with PGA, and there is no net carbon gain of the process. "In the further metabolism of glycolate, CO2 is released. This is called photorespiration and its rate is, in contrast to m#itochondrial or dark respiration, strongly enhanced by O2 and light. In the C4 pathway, atmospheric CO2 is fixed, via the $enzyme PEPcase, by a three-carbon compound to yield one molecule of malate or aspartate (four-carbon compounds). In C4 pla%nts, this occurs in mesophyll cells. Malate or aspartate is then transported to bundle sheath cells where it is decarboxyl&ated, and the released CO2 is refixed via the C3 pathway. There is no apparent photorespiration in C4 plants, because CO2 'levels in the vicinity of RuBPcase are probably elevated and any CO2 released from the bundle sheath cells is efficiently (refixed via PEPcase in the mesophyll cells. In CAM plants, atmospheric CO2 is fixed into malate during the night while the) decarboxylation and refixation of CO2 occurs in the daytime. The C4 pathway provides C4 and CAM plants with an efficient *carbon-capturing system complementing the basic C3 pathway. In C4 plants this leads to a higher net CO2 incorporation rate+ than in C3 plants under high light and temperature regimes such as are found in the tropics. In CAM plants it allows for  nightly CO2 fixation in arid climates where opening of stomates during the day would cause excessive water loss..74^2^Beerling,D J^Chaloner,W G^1993^1^The Impact of Atmospheric CO2 and Temperature Change on Stomatal Density: Observatio+ns from _Quercus robur_ Lammas Leaves^35^71^^231-235^^^^^^^^^^176^^^^^^^^^^^Quercus roburur L.C^174^Ann. Bot..1A^174^A comparative study of leaves formed on shoots during the spring and summer (lammas) of _Quercus robur_ from three c92ontrasting geographical locations (Cardiff, Durham and London) gives a measure of the effect of temperature on stomatal de3nsity. This is of value in attempting to distinguish the effects of CO2 and temperature on observed stomatal density chang<4es under different CO2 and temperature conditions through the Quaternary. These leaves of normal and lammas shoots will haF5ve developed under similar CO2 levels but different environmental temperatures. Our results demonstrate that leaves formed6 under the warmer summer temperatures had reduced stomatal densities and indices from all sites, compared with their sprinI7g counterparts. This trend was also detected from measurements of spring and summer leaves made upon herbarium material coS8llected from the same tree in 1840. The results suggest that for _Q. robur_ temperature overrides the influence of irradia9nce intensity and small seasonal (75^2^Beerling,D J^Chaloner,W G^1993^1^Stomatal Density Responses of Egyptian _Olea europaea_ L. Leaves to CO2 Change Since 1327 BC^35^71^^431-435^^^^^^^^^^179^^^^^^^^^^^Olea europaea/olivelive~/C^177^Ann. Bot.AA^177^We have attempted to separate the effects of CO2 and temperature change on stomatal density by examining ancient leaBf material of _Olea europaea_ L. The distribution of this species is confined to a Mediterranean type climate, so that _O.C europaea_ leaves of different ages will have formed under similar temperatures but different CO2 levels over the last 300D0 years. Stomatal density measurements have been made upon leaves of _O. europaea_ originating from King Tutankhamun's tomEb dating from 1327 BC, and have been compared with values obtained from Egyptian _O. europaea_ material dating from pre-33F2 BC, 1818 and 1978 AD. Together, the four dates provide a record of how the plant has responded to increases in atmospherGic CO2 concentration during that time. The results demonstrate that in accordance with similar studies examining the stomaHtal density response of plants over three time scales (hundreds, thousands and tens of thousands of years) stomatal densitIy falls as CO2 levels increase. Since we have examined a natural system with leaves developing under similar environmentalJ temperatures the results confirm observations from experimental studies in which plants were grown under the same temperature but different CO2 regimes.      L76^6^Beerling,D J^Chaloner,W G^Huntley,B^Pearson,J A^Tooley,M J^Woodward,F I^1992^1^Variations in the Stomatal Density of M_Salix herbacea_ L. under the Changing Atmospheric CO2 Concentrations of Late- and Post-glacial Time^36^336^^215-224^^^^^^^^^^182^^^^^^^^^^^Salix herbaceaea L.?C^180^Phil. Trans. R. Soc. Lond. B.PA^180^The rapidly rising CO2 concentration of the past 200 years has been shown to be accompanied by a fall in stomatal deQnsity in the leaves of temperate trees. The present study attempts to investigate the relationship of atmospheric CO2 chanRge and stomatal density in the arctic-alpine shrub, _Salix herbacea_, over the longer time span of 11,500 years offered byS fossil leaves from post-glacial deposits. Comparisons of fossil material from Scotland and Norway are made with leaves frTom living populations growing in Austria, Greenland and Scotland. The Austrian material, from an altitudinal gradient betwUeen 2000 and 2670 m above sea level, gives added comparisons of contemporary differences of CO2 partial pressure with altiVtude. The results of our investigation indicate, rather surprisingly, that the rising CO2 concentration of the past 11,500W years has been accompanied by an increase in the stomatal density of _S. herbacea_ in contrast to the shorter-term observXations on the herbarium material of temperate trees. The most likely explanation appears to centre on the temperature and Ywater availability of the early post-glacial environment overriding the effect of the lower CO2 regime. However, the scaleZ of the time interval involved may also be significant. Natural selection over the 11,500 year period concerned may have f[avoured a different response to what is, in effect, an acclimatory response observed in trees within the period of rapid CO2 rise of the past 200 years..ۘ* xZ'3*p*@@ ]77^2^Beeson,R C,Jr^Graham,M E D^1991^1^CO2 Enrichment of Greenhouse Roses Affects Neither Rubisco nor Carbonic Anhydrase Activities^3^116^^1040-1045^^^^^^^^^^2059^^^^^^^^^^^Rosa hybrida/rose^^^^^  WordPerfect NC^183^J. Amer. Soc. Hort. Sci.  6.0     `78^2^Bellamy,L A^Kimball,B A^1986^3^CO2 Enrichment Duration and Heating Credit as Determined by Climate^Physiology, Yield,"a and Economics^CRC Press, Inc.^Boca Raton, Florida^168-197^^^^II^^Carbon Dioxide Enrichment of Greenhouse Crops^^^^186^^^^%^^^^^^^^^^^^^^^^^Enoch,HZ^Kimball,B AB A   (cA^185^To determine if it is economical to invest in CO2 enrichment equipment, a detailed economic analysis considering the4d increases in income and operating expenses should be performed. The procedure for such an analysis is straightforward (e.eg., Chapter 13) but it is necessary to make estimates of the percent increase in yield, the amount of CO2 used, and of any7f reduction in heating energy requirements resulting from a combustion-type CO2 generator. For any given greenhouse and croBgp, these three factors will vary with the local climate and in particular, with the outside air temperature, and global soEhlar radiation. It is practical to enrich with CO2 only while a greenhouse is closed and not ventilated. Therefore, CO2 enrPiichment duration equals day length minus ventilation time. Using Kimball's MEB program curves were generated which show thUje ventilation time fraction a 0.05 m3/m2/s capacity (47 greenhouse volume changes per hour) fan would need to operate to mYkaintain a given set point temperature as a function of transmitted solar radiation for various ambient air temperatures. S^limilar curves were generated showing the heating credit from a CO2 generator rated at 42.5 W/m2 (CO2 output 9.5 g/m2/h). Hbmourly solar radiation and temperature data for days typical of each month of the year for six climate regions were generatned using simple models from values of monthly mean minimum and maximum temperatures and mean total daily global radiation.eo Such data should be available nearby to most greenhouse locations. The hourly climate data for each of the typical monthlqpy days were used in conjunction with the ventilation time fraction curves to compute the ventilation requirement throughouqt the year for six locations--Oslo, Norway; De Bilt, Netherlands; Milan, Italy; Columbus, Ohio, U.S.; Tokyo, Japan; Tel Avuriv, Israel. The number of hours at which the greenhouse operated in five ventilation classes (0%, 0 to 20%, 20 to 50%, 50 sto 100%, 100%) for a 30C ventilation temperature setpoint were plotted. For all sites except Tel Aviv, enrichment is possxtible throughout the whole day during winter. At Oslo, a greenhouse can remain unventilated and enriched for up to 7 monthsu of the year. The areas in each ventilation class were measured to estimate the corresponding annual number of hours of povssible CO2 enrichment. From these CO2 enrichment duration values, the required amounts of CO2 can be estimated. The amountw of solar radiation received by the crop during each of the ventilation classes was also determined, so that the percent ixncrease in yield due to CO2 enrichment could be calculated. A greenhouse in Oslo can remain closed and CO2 enriched for 79y% of the total annual daylight hours, yet only 51% of the total radiation is received by the crop during this time. Using zthe assumption that yield is directly proportional to transmitted solar radiation, yields with and without CO2 enrichment {were compared for the six locations to assess the effect of climate on percent yield increase. Annual yields could be incr|eased 2% at Tel Aviv and 26% at Oslo if enrichment is limited to when the greenhouse remains completely closed. If CO2 is }pulsed into the greenhouse between intervals of fan operation, these CO2 response values can increase to 22 and 48%, respe~ctively. The effects on CO2 enrichment duration of using 'hot' CO2 from a combustion-type generator rather than 'cold' CO2 from other sources were computed for the Tel Aviv location. Using a 27C greenhouse air temperature for the ventilation setpoint, average daily CO2 enrichment duration (0% ventilation) was 4.0 hr during the winter using cold CO2, but decreased to 2.6 hr with hot CO2. Finally, the annual heating credit was determined for each of the six locations for 15C day heating setpoint, and the annual and winter savings in heating energy requirements were tabulated. The proportion of annual CO2 enrichment duration (0% ventilation) that was heating credit time ranged from 49% for Oslo to 8% for Tel Aviv."\79^2^Bentley,B L^Johnson,N D^1990^3^Plants as Food for Herbivores: The Roles of Nitrogen Fixation and Carbon Dioxide Enrichment^Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions^John Wiley & Sons, Inc.^^257-272^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Price,PW^Lewinsotin,TM^Fernandes,GW^Benson,WWZi~~0XCF@80^2^Berntson,G M^Woodward,F I^1992^1^The Root System Architecture and Development of _Senecio vulgaris_ in Elevated CO2 and Drought^37^6^^324-333^^^^^^^^^^190^^^^^^^^^^^Senecio vulgaris^dpD$NsLp'oy!oF>^C^188^Funct. Ecol.d>$"8>F"dZz+!p'd#C@dd#CC$dCC+a *FS3A^188^1. The impact of elevated CO2 and drought on the architecture and development of root systems of _Senecio vulgaris_ was examined and implications for water and nutrient uptake discussed. Plants were grown in miniature rhizotrons to non-destructively monitor the development of roots _in situ_ at both an elevated (700 umol/mol) and ambient (350 umol/mol) atmospheric CO2 concentration and high or low supply of water. 2. CO2 and water had a significant impact on the way that _S. vulgaris_ root systems filled the soil matrix. Elevated CO2 resulted in more branched, longer root systems that foraged through larger volumes of soil. Under elevated CO2 and a low water supply, root systems had branching and foraging patterns and root length similar to those grown under ambient CO2 with a high water supply. 3. Overall, water had a more pronounced impact on the growth rate of _S. vulgaris_ roots than did CO2. The density of rooting remained unchanged across all treatments. Thus, under elevated CO2 the intensity of foraging _S. vulgaris_ root systems might be unchanged while the extent of  foraging by these root systems, as indicted by the horizontal spread of roots, may be increased.$ 6Fi?5T5Zr4581^1^Besford,R T^1990^1^The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Relative Changes in Calvin Cycle Enzymes^38^136^^458-463^^^^^^^^^^192^^^^^^^^^^^Lycopersicon esculentum^^^^^^WO6P|PPGQNQQQ R"/ A^191^Tomato plants (cv. Findon Cross) were grown in a normal concentration of CO2 (approximately 340 vpm) or in elevated CO2 (1000 vpm) with a 12 h photoperiod of 400 umol quanta/m2/s, PAR. The activities of three Calvin cycle enzymes, RuBPco !(E.C. 4.1.1.39), 3 phosphoglyceric acid phosphokinase (E.C. 2.7.2.3) and NADP-dependent glyceraldehyde 3-phosphate dehydro6genase (E.C. 1.2.1.13) were determined in extracts from the unshaded 5th leaf during leaf development. RuBPco activity was reduced in the high-CO2 grown leaves at 60% expansion compared with leaves grown in 340 vpm CO2, but there were no appare9nt differences in the other two Calvin cycle enzymes at this stage of expansion. With subsequent leaf development in high FCO2 there was an accelerated decline in all three enzyme activities. The loss of RuBPco activity was studied further by raising antibodies to RuBPco and the large subunit of RuBPco (LSU) was detected in electroblotted crude extracts from normalI and high-CO2 grown plants. This specific immunoassay estimated a 75% reduction of LSU in the high-CO2 grown leaf at full Wexpansion.Xu7vX7vX7vX7vX7vX7vX7vX<8vX8vXvXvXvX7vXLvX]vXbvXlvXwvXvXvXvX4vXKvXRvXXvXvXvX[82^1^Besford,R T^1993^1^Photosynthetic Acclimation in Tomato Plants Grown in High CO2^123^104/105^^441-448^^^^^^^^^^195^^^^^^^^^^^Lycopersicon esculentum/tomato^^^^^^^^^^vX+vX+vX+vX+vX+vX+vX+vX+vX+vX,vX,vX,vX ,vX&,vX2,vXe,vX^wth and dinitrogen fixation in the vegetative growth stage were examined. 1. The whole plant weight of the cultivated soyb_A^193^The effects of prolonged CO2 enrichment of tomato plants on photosynthetic performance and Calvin cycle enzymes, including the amount and activity of ribulose-1,5-bisphosphate carboxylase (RuBPco), were determined. Also the light-saturatebd rate of photosynthesis (Pmax) of the 5th leaf throughout leaf development was predicted based on the amount and kineticso of RuBPco. With short-term CO2 enrichment, i.e. only during the photosynthesis measurements, Pmax of the young leaves did not increase while the leaves reaching full expansion more than doubled their net rate of CO2 fixation. However, with lonrger-term CO2 enrichment, i.e. growing the crop in high CO2, the plants did not maintain this photosynthetic gain. Compared| with leaves of plants grown in normal ambient CO2 the high CO2-grown leaves, when almost fully expanded, contained only about half as much RuBPco protein and Pmax in 300 and 1000 vpm CO2 was similarly reduced. The loss of RuBPco protein may be a factor associated with the accelerated fall in Pmax since Pmax was close to that predicted from the amount and kinetics of RuBPco assuming RuBP saturation. Acclimation to high CO2 is fundamentally different from acclimation to high light. In contrast to acclimation to high light, acclimation to high CO2 does not usually involve an increase in photosynthetic machinery so the synthesis and maintenance costs (as indicate by the dark respiration rate) are generally lower..0S183^2^Besford,R T^Hand,D W^1989^1^The Effects of CO2 Enrichment and Nitrogen Oxides on some Calvin Cycle Enzymes and Nitrite Reductase in Glasshouse Lettuce^39^40^^329-336^^^^^^^^^^198^^^^^^^^^^^Lactuca sativa L.N~C^196^J. Exp. Bot.A^196^Glasshouse lettuce (cvs Pascal and Talent) was grown during late autumn and early winter in an atmosphere polluted with nitrogen oxides (NOx) generated from direct-fired natural gas burners used for CO2 enrichment and warm air heating (high CO2 + NOx treatment). Concentrations of 0.3-0.4 vpm NOx were detected during the daytime when near 3-fold CO2 enrichment (1000 vpm) was practised without heating. In cold weather, the CO2 and NOx levels were dependent on the amount of heating required to maintain minimum temperatures of 5C (night) and 7C (day). Concentrations of between 2000-5000 vpm CO2 and 1-2.5 vpm NOx were recorded at night during an intensely cold period in early January just prior to sampling for leaf enzymes. The plants were compared with those grown in unpolluted atmospheres with either a natural (340 vpm) or an enriched level (1000 vpm) of CO2. Pascal grown in elevated CO2 had less activity per g fresh weight of RuBPc (E.C. 4.1.1.39), 3PGA phosphokinase (E.C. 2.7.2.3) and NADP-G3P dehydrogenase (E.C 12.1.13) than plants grown in a normal ambient CO2 atmosphere. The cytoplasmic enzyme PEPc (E.C. 4.1.1.31) was not significantly affected by the pure CO2 enrichment. With high CO2 + NOx the activities of the Calvin cycle enzymes were restored to values close to those present in non-enriched plants, while the activity of PEPc was increased. The activity of nitrite reductase (NiR) (E.C. 1.7.7.1) was increased in Pascal and Talent by high CO2 + NOx. Immunoblotting techniques were used to show that the increase in activity of this enzyme was accompanied by an increase in the steady state concentration of the protein. Only one molecular form of NiR was detected by immunoblotting, and it would appear that the 'induction' of NiR activity resulted from increased net enzyme synthesis rather than activation of pre-existing enzyme. At the time of sampling no visible damage by high CO2 and NOx was evident and the lack of symptoms may have been associated with the enhanced levels of nitrite reductase in these cultivars.84^3^Besford,R T^Ludwig,L J^Withers,A C^1990^1^The Greenhouse Effect: Acclimation of Tomato Plants Growing in High CO2, Photosynthesis and Ribulose-1, 5-_Bis_phosphate Carboxylase Protein^39^41^^925-931^^^^^^^^^^201^^^^^^^^^^^Lycopersicon esculentumumC^199^J. Exp. Bot.A^199^Tomato plants were grown in solution culture in a controlled environment at 20C with a 12 h photoperiod of 400 umol# quanta/m2/s PAR with either normal ambient CO2, approximately 340 vpm, or with 1000 vpm CO2. The short- and long-term eff/ects of CO2 enrichment on photosynthesis were determined together with the levels of ribulose-1,5-_bis_phosphate carboxyla3se (RuBPco) EC. 4.1.1.39 protein and activity throughout leaf development of the unshaded 5th leaf above the cotyledons. T6he high CO2 concentration during growth did not appreciably affect the rate of leaf expansion or final leaf area but did iBncrease the fresh weight per unit area of leaf. With short-term CO2 enrichment, i.e. only during the photosynthesis measurements, the light-saturated photosynthetic rate (Pmax) of young leaves did not increase while those reaching full expansioFn more than doubled their net rate of CO2 fixation. However, with longer term CO2 enrichment, i.e. growing the crop in higUh CO2, the plants did not maintain this photosynthetic gain. While the CO2 concentration during growth did not affect the peak in Pmax measured in 300 vpm CO2 or Pmax measured in 1000 vpm CO2, RuBPco protein or its activity, the subsequent ontoXgenetic decline in these parameters was greatly accelerated by the high CO2 treatment. Compared with plants grown in normal ambient CO2 the high CO2 grown leaves, when almost fully expanded, contained only approximately half as much RuBPco prot[ein and Pmax in 300 vpm CO2 and Pmax in 1000 vpm CO2 were similarly reduced. The loss of RuBPco protein may be a major facetor associated with the accelerated fall in Pmax since it was close to that predicted from the amount and kinetics of RubBPco assuming RuBP saturation. In the oldest leaves examined grown in high CO2 additional factors may be limiting photosynthhesis since RuBPco kinetics marginally overestimated Pmax in 300 vpm CO2 and the initial slope of photosynthesis in responrse to intercellular CO2 was also less than expected from the extractable RuBPco.@@ @ @ WPCs85^5^Betsche,T^Morin,F^Cotte,F^Gaugain,F^Andr,M^1989^3^Gas Exchanges, Chlorophyll _a_ Fluorescence, and Metabolite Levelsu in Leaves of _Trifolium subterraneum_ during Long-term Exposure to Elevated CO2^Progress in Photosynthesis Research, Proc|. VIIIth International Congress on Photosynthesis, Stockholm, Sweden, 1989^^^^^^^^^^^^^203^^^^^^^^^^^Trifolium subterraneuA^202^High CO2 stimulates photosynthesis of C3-plants initially, but then photosynthesis often declines and undesirable effects such as excessive starch accumulation and yellowing of leaves can occur. Results from chlorophyll _a_ fluorescence measurements and metabolite determinations indicate that high CO2 can perturb photosynthesis probably on the level of phosphate recycling. We propose that the absence of photorespiration in high CO2 causes phosphate deficiency in the chloroplast stroma and a low phosphorylation potential in the cytosol. Both conditions favour the synthesis of starch.86^1^Bhattacharya,N C^1992^3^Prospects of Agriculture in a Carbon Dioxide-enriched Environment^A Global Warming Forum: Scientific, Economic and Legal Overview^CRC Press, Inc.^Boca Raton, Florida^^^^^^^^^^^205^^^^^^^^^^^^^^^^^^^^^Geyer,R AA^204^The CO2 concentration in the atmosphere is steadily increasing. It has been predicted that it will double the preindustrial level (270 umol/mol) by the year 2080. Investigations conducted on different food and fiber crops in response to elevated CO2 in phytotrons, glasshouses, open-top chambers, SPAR units, and Face environments have generally showed increases in growth and yields of most of the crops, although some plants responded negatively to increased concentrations of CO2. The increased growth of plants in a CO2-enriched environment may rapidly deplete nutrients from the soil and consequently, positive effects of CO2 may not persist under low fertility levels. Similarly, interactive effects of high CO2 with high temperature may not be good for all plant species because of specific temperature requirements for each plant. In certain cases, plants may remain vegetative at high temperatures throughout the growth cycle. Therefore, cropping patterns may have to be modified with the increase in atmospheric temperature in the future world of high CO2. Interestingly, water use efficiency of plants in a CO2-enriched environment may have beneficial effects in tropical and subtropical regions of the world where water is limited for crop production. Elevated CO2 in the atmosphere results in increased concentrations of carbohydrates and 'dilution' of other metabolites such as chlorophyll, proteins, amino acids, carotene and reduced nutrients in plant tissues. Increasing atmospheric CO2 may alter plant/herbivore interactions. The impact of leaf-eating herbivores may increase as the level of atmospheric CO2 rises. Furthermore, C3 weeds may grow faster than C4 crops of agricultural importance in a CO2-enriched environment, and vice versa. In unmanaged ecosystems, these effects of elevated CO2 may cause marked changes.SUP\WP{WPC}.DLN\WP{WPC}.DLNWP}WPC{.GMKWP}WPC{.GKGMK.EXEC:\WP60\WP.FIL87^4^Bhattacharya,N C^Bhattacharya,S^Strain,B R^Biswas,PK^1989^1^Biochemical Changes in Carbohydrates and Proteins of Sweet Potato Plants (_Ipomoea batatas_ [L.] Lam.) in Response to Enriched CO2 Environment at Different Stages of Growth and Development^38^135^^261-266^^^^^^^^^^208^^^^^^^^^^^Ipomoea batatas/sweet potatosweet potatoo;5Hs8C^206^J. Plant Physiol.ggHP;5H8000A^206^Sweet potato (_Ipomoea batatas_ [L.] Lam., cv. Georgia Jet) plants were grown at different CO2 concentrations (350, 675 and 1000 umol/mol) in controlled environment conditions. The effect of CO2 enrichment on carbohydrate concentrations i n leaves, stems, roots and tubers at different stages of growth and development were investigated. The glucose, sucrose and starch concentrations in leaves increased during 0-35 days after planting as compared to stems and roots receiving incre ased CO2 concentrations. However, starch and glucose concentrations increased significantly in tubers during the 50-65 day interval which corresponded with rapid growth of tubers at high CO2 concentrations. Increasing CO2 concentrations did not raise the protein content of leaves, roots or tubers at any stages of growth and development. CO2 enrichment increased the soluble protein concentration in stems during the 20-50 day growth interval which subsequently decreased at maturity.88^5^Bhattacharya,N C^Bhattacharya,S^Strain,B R^Biswas,P K^Tolbert,M E M^1986^3^An Insight into the Mechanism of Auxin Action in Rooting Hypocotyl Cuttings of _Impatiens balsamina_ Grown in Phytotron under Enriched CO2 Environment^Proc., Thirte