ÿWPCB ûÿ2idge­ äuªë &ÆÀG«&ÆÀGƒéëæ3À^_Alphabetic List Listed with Format STRAIN Listing Created 17 Feb 1995, at 13:09 à Ã1Ä Ä° `  à ÃAckerly, D.D., J.S. Coleman, S.R. Morse, and F.A. Bazzaz.Ä Ä 1992. CO2 and Temperature Effects on Leaf Area Production in Two Annual Plant Species. ÃÃEcology 73:1260©1269.ÄÄ We studied leaf area production in two annual plant species, ÃÃAbutilon theophrastiÄÄ and ÃÃAmaranthus retroflexusÄÄ, under three day/night temperature regimes (18/14À$ÀC, 28/22À$ÀC, and 28/31À$ÀC) and two concentrations of carbon dioxide (400 and 700 uL/L). The production of whole©plant leaf area during the first 30 d of growth was analyzed in terms of the leaf initiation rate, leaf expansion, individual leaf area, and, in ÃÃAmaranthusÄÄ, production of branch leaves. Temperature and CO2 influenced leaf area production through stem (the plastochron index), and through shifts in the relationship between whole©plant leaf area and the number of main stem nodes. In ÃÃAbutilonÄÄ, leaf initiation rate was highest at 38À$ÀC, but area of individual leaves was greatest at 28À$ÀC. Total leaf area was greatly reduced at 18À$ÀC due to slow leaf initiation rates. Elevated CO2 concentration increased leaf initiation rate at 28À$ÀC, resulting in an increase in whole©plant leaf area. In ÃÃAmaranthusÄÄ, leaf initiation rate increased with temperature, and was increased by elevated CO2 at 28À$ÀC. Individual leaf area was greatest at 28À$ÀC, and was increased by elevated CO2 at 28À$ÀC but decreased at 38À$ÀC. Branch leaf area displayed a similar response to CO2, but was greater at 38À$ÀC. Overall, whole©plant leaf area was slightly increased at 38À$ÀC relative to 28À$ÀC, and elevated CO2 levels resulted in increased leaf area at 28À$ÀC but decreased leaf area at 38À$ÀC. The effects on leaf area closely parallel rates of biomass accumulation in the same experiment, suggesting that responses of developmental processes to elevated CO2 and interacting factors may play an important role in mediating effects on plant growth. Abutilon theophrasti/Amaranthus retroflexus ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, LEAF AREA DEVELOPMENT, OLD FIELD COMMUNITIES, PLASTOCHRON INDEX, TEMPERATUREÄÄ Ã Ã2Ä Ä° `  à ÃAcock, B.Ä Ä 1990. Effects of CO2 on Photosynthesis, Plant Growth and Other Processes. ÃÃIN: Impact of CO2, Trace Gases, and Climate Change on Global Agriculture, ASA Special Publication No. 53 (B.A. Kimball, N.J. Rosenberg, and L.H. Allen Jr., eds.), American Society of Agronomy, Madison, Wisconsin, pp. 45©60.ÄÄ ÃÃKEYWORDS: AGRICULTURE, ALLOCATION, CROPS, GROWTH, PHOTOSYNTHESIS, PHYSIOLOGICAL CO2 RESPONSES, REVIEWÄÄ Ã Ã3Ä Ä° `  à ÃAcock, B., M.C. Acock, and D. Pasternak.Ä Ä 1990. Interactions of CO2 Enrichment and Temperature on Carbohydrate Production and Accumulation in Muskmelon Leaves. ÃÃJournal of the American Society of Horticultural Science 115:525©529.ÄÄ We examined how temperature and stage of vegetative growth affect carbohydrate production and accumulation in ÃÃCucumis meloÄÄ 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 starch 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 significantly 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 higher 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]. muskmelon/Cucumis melo ÃÃKEYWORDS: CARBOHYDRATES, GROWTH ANALYSIS, GROWTH STAGES, NAR, SPAR UNITS, TEMPERATUREÄÄ Ã Ã4Ä Ä° `  à ÃAcock, B., M.C. Acock, V.R. Reddy, and D.N. Baker.Ä Ä 1985. The Simulation, with GLYCIM, of Soybean Crops Grown in the Field and at Various CO2 Concentrations in Open©top Chambers during 1982ÃÃ, 011 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean ÃÃKEYWORDS: CROP MODEL, MODELING, OPEN©TOP CHAMBERS, SIMULATIONÄÄ Ã Ã5Ä Ä° `  à ÃAcock, B., and L.H. Allen Jr.Ä Ä 1985. Crop Responses to Elevated Carbon Dioxide Concentrations. ÃÃIN: Direct Effects of Increasing Carbon Dioxide on Vegetation, DOE/ER©0238 (B.R. Strain and J.D. Cure, eds.), Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C., pp. 53©97.ÄÄ ÃÃKEYWORDS: CROP MODEL, ENVIRONMENTAL INTERACTIONS, PHOTOSYNTHESIS, REVIEW, TRANSPIRATION, WUEÄÄ Ã Ã6Ä Ä° `  à ÃAcock, B., D.N. Baker, V.R. Reddy, J.M. McKinion, F.D. Whisler, D. Del Castillo, and H.F. Hodges.Ä Ä 1982. Soybean Responses to Carbon Dioxide: Measurement and Simulation 1981ÃÃ, 004 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: ALLOCATION, CANOPY PHOTOSYNTHESIS, MODELING, RESPIRATION, ROOTS, SPAR UNITSÄÄ Ã Ã7Ä Ä° `  à ÃAcock, B., and D. Pasternak.Ä Ä 1986. Effects of CO2 Concentration on Composition, Anatomy, and Morphology of Plants. ÃÃIN: Physiology, Yield and Economics, Vol. II (H.Z. Enoch and B.A. Kimball, eds.), Carbon Dioxide Enrichment of Greenhouse Crops, CRC Press, Inc., Boca Raton, Florida, pp. 41©52.ÄÄ In summary, we can say that species differ in their response to high CO2. Plants which are using CAM are relatively unresponsive. Other plants with the C4 pathway show modest dry weight gains but large reductions in transpiration rate. Plants which only have the C3 pathway, or well©watered CAM plants which are behaving like C3 plants, exhibit modest reductions in transpiration rate and large gains in dry weight, resulting in a variety of changes in plant composition, anatomy, and morphology. We know too little to even begin dividing C3 species into response groups. However, we can describe a typical or average response as follows. All organs on the plants become heavier with roots gaining proportionally more dry weight than stems, and stems more than leaves. The additional dry matter in the root is mainly used to increase root length with very little going to increase the density of the root tissue. Additional dry matter going to the stem causes increases in its height and diameter and little increase in the density of the tissue. Additional dry matter going to the leaves causes both a small increase in leaf area and a small increase in leaf thickness. There is an increase in structural dry matter 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, depending 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. ÃÃKEYWORDS: ALLOCATION, C3, C4, REVIEWÄÄ Ã Ã8Ä Ä° `  à ÃAcock, B., V.R. Reddy, D. Del Castillo, H.F. Hodges, D.N. Baker, J.M. McKinion, and F.D. Whisler.Ä Ä 1983. Soybean Responses to Carbon Dioxide: Measurement and Simulation 1982ÃÃ, 008 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, MODELING, PHOTOSYNTHESIS MODEL, RESPIRATION, SIMULATION, SPAR UNITS, WATER STRESS, YIELDÄÄ Ã Ã9Ä Ä° `  à ÃAcock, B., V.R. Reddy, H.F. Hodges, D.N. Baker, and J.M. McKinion.Ä Ä 1985. Photosynthetic Response of Soybean Canopies to Full©Season Carbon Dioxide Enrichment. ÃÃAgronomy Journal 77:942©947.ÄÄ Global atmospheric CO2 concentration ([CO2]) is increasing as a result of the burning of fossil fuels. At present there is little information about how agronomic crops will respond to future high [CO2]. To investigate the basic process that will be most affected, soybean canopies were continuously exposed to various [CO2] and photosynthetic rates were measured throughout the growing season. Soybean was grown to physiological maturity in sunlit controlled©environment chambers in CO2 concentrations of 330, 450, 600 and 800 uL/L. Carbon dioxide fluxes were measured on the canopies at 15©min intervals every day and used to calculate photosynthetic and respiration rates. Gross photosynthetic rate increased with each increment in [CO2] regardless of stage of development, but there was considerable day©to©day and seasonal variation. Seasonal changes in photosynthetic rate were associated with developmental changes in the crop. Photosynthetic rates were low during early vegetative development, even after the canopy had closed, but increased threefold just before flowering to reach a peak during flowering at stage R2. They then decreased by 30% or more until just before the start of pod expansion (R3) when a 45% increase occurred. Thereafter, photosynthetic rates decreased slowly and continuously to final harvest. The daily curves of photosynthetic rate ÃÃvs.ÄÄ photosynthetic photon flux density were further analyzed to determine canopy light utilization efficiency (ÀÀ) and canopy conductance to CO2 transfer (À)À). Plants grown in 800 uL/L [CO2] had a value of ÀÀ that averaged about 40% higher than that for plants grown in 330 uL/L and a value of À)À that averaged about 24% lower for the season. Differences in ÀÀ between these treatments were significant throughout the season, while initial differences in À)À between treatments became less obvious after late vegetative growth stage VII. soybean/Glycine max ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CONDUCTANCE, LIGHT UTILIZATION EFFICIENCY, PHOTOSYNTHESIS MODEL, SPAR UNITSÄÄ Ã Ã10Ä Ä° `  à ÃAcock, B., V.R. Reddy, F.D. Whisler, D.N. Baker, J.M. McKinion, H.F. Hodges, and K.J. Boote.Ä Ä 1983. The Soybean Crop Simulator GLYCIM: Model DocumentationÃÃ, 002 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CROP MODEL, MODELINGÄÄ Ã Ã11Ä Ä° `  à ÃAcock, B., and A. Trent.Ä Ä 1991. The Soybean Crop Simulator GLYCIM: Documentation for the Modular Version 91ÃÃ, 017 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CROP MODEL, GENERIC MODEL, SIMULATIONÄÄ Ã Ã12Ä Ä° `  à ÃAizawa, K., Y. Nakamura, and S. Miyachi.Ä Ä 1985. Variation of Phosphoenolpyruvate Carboxylase Activity in ÃÃDunaliellaÄÄ Associated with Changes in Atmospheric CO2 Concentration. ÃÃPlant Cell Physiology 26:1199©1203.ÄÄ In ÃÃDunaliella tertiolectaÄÄ, ÃÃD. bioculataÄÄ and ÃÃD. viridisÄÄ the activities of phosphoenolpyruvate carboxylase and carbonic anhydrase were higher in the cells grown in ordinary air (low©CO2 cells) than in those grown in air enriched with 1©5% CO2 (high©CO2 cells), whereas in ÃÃPorphyridium cruentumÄÄ R©1 there was no difference in phosphoenolpyruvate carboxylase activity between these two types of cells. Apparent Km (NaHCO3) values for photosynthesis in low©CO2 cells of all species tested were smaller than those in high©CO2 cells. Most of the 14C was incorporated into 3©phosphoglycerate, sugar mono© and di©phosphates during the initial periods of photosynthetic NaH14CO3©fixation, indicating that both types of cells in ÃÃD. tertiolectaÄÄ are C3 plants. Dunaliella tertiolecta/Dunaliella bioculata/Dunaliella viridis/Porphyridium cruentum ÃÃKEYWORDS: ALGAE, AQUATIC PLANTS, CARBONIC ANHYDRASE, CELL CULTURE, ENZYMES, PHOSPHOENOLPYRUVATE CARBOXYLASEÄÄ Ã Ã13Ä Ä° `  à ÃAkey, D.H., and B.A. Kimball.Ä Ä 1989. Growth and Development of the Beet Armyworm on Cotton Grown in an Enriched Carbon Dioxide Atmosphere. ÃÃSouthwestern Entomologist 14:255©260.ÄÄ Growth and development were studied in the beet armyworm (BAW), ÃÃSpodoptera exiguaÄÄ (HÀGÀbner), reared on cotton seedlings at high (640 uL/L) or ambient (320 uL/L) carbon dioxide (CO2) levels and at two fertilizer levels. Under high fertilization, female BAW reared on CO2 enriched seedlings weighed significantly less (87.3 mg) than controls (101.0 mg) and had a significantly longer developmental time (14.2 versus 12.4 days for controls). Male BAW followed the same pattern, but the differences were not statistically significant. Combined (male and female) survival rates for BAW reared on CO2©enriched cotton seedlings on a high fertilizer level were 19.1 compared to 41.6% for controls; more females survived than males by a significant ratio of 2:1. cotton/Gossypium hirsutum ÃÃKEYWORDS: BEET ARMYWORM, INSECTS, OPEN©TOP CHAMBERS, SPODOPTERA EXIGUAÄÄ Ã Ã14Ä Ä° `  à ÃAkey, D.H., B.A. Kimball, and J.R. Mauney.Ä Ä 1988. Growth and Development of the Pink Bollworm,Ãà Pectinophora gossypiellaÄÄ (Lepidoptera: Gelechiidae), on Bolls of Cotton Grown in Enriched Carbon Dioxide Atmospheres. ÃÃEnvironmental Entomology 17:452©455.ÄÄ The pink bollworm, ÃÃPectinophora gossypiellaÄÄ (Saunders), was reared on the bolls of cotton plants grown in CO2©enriched (649 uL/L) and ambient (371 uL/L) chambers and in two open field plots, one with free©air CO2 enrichment (522 uL/L) and one without enrichment (ambient CO2, 360 uL/L). The effects of increased CO2 levels on growth and development were examined. There was no difference in pupal weights of pink bollworm raised on CO2©enriched cotton compared with those raised on ambient CO2 cotton (26.80 versus 26.64 mg, respectively). Also, there was no difference in developmental time (21©27 d). Analysis of percent seed damage by larvae showed no differences between CO2©enriched and ambient CO2 cotton. These results 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. cotton/Gossypium hirsutum ÃÃKEYWORDS: CARBON:NITROGEN RATIO, INSECTS, OPEN©TOP CHAMBERS, PECTINOPHORA GOSSYPIELLA, PINK BOLLWORM, SEED DAMAGE, SEEDSÄÄ Ã Ã15Ä Ä° `  à ÃAllen, L.H., Jr.Ä Ä 1990. Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants. ÃÃJournal of Environmental Quality 19:15©34.ÄÄ As global population increases and industrialization expands, carbon dioxide (CO2) and toxic air pollutants can be expected to be injected into the atmosphere at increasing rates. This analysis reviews a wide range of direct plant responses 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 review of effects of potential climatic change on plants is not a major objective of this analysis. Research shows that elevated CO2 increases photosynthetic rates, leaf area, biomass, and yield. Elevated CO2 also reduces transpiration rate per unit 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. ÃÃKEYWORDS: AIR POLLUTION, CLIMATE CHANGE, CONDUCTANCE, REVIEW, TRANSPIRATION, WUEÄÄ Ã Ã16Ä Ä° `  à ÃAllen, L.H., Jr.Ä Ä 1991. Effects of Increasing Carbon Dioxide Levels and Climate Change on Plant Growth, Evapotranspiration, and Water Resources. ÃÃIN: Managing Water Resources in the West under Conditions of Climate Uncertainty; 1990 Nov. 14©16; Scottsdale, Arizona (Committee on Climate Uncertainty and Water Resources Management, ed.), National Academy Press, Washington, D.C., pp. 101©147.ÄÄ soybean/Glycine max ÃÃKEYWORDS: AGRICULTURE, CLIMATE CHANGE, CLIMATE MODEL, EVAPOTRANSPIRATION, GCM'S, MODELING, REVIEW, STREAMFLOW, WUEÄÄ Ã Ã17Ä Ä° `  à ÃAllen, L.H., Jr.Ä Ä 1992. Free©Air CO2 Enrichment Field Experiments: An Historical Overview. ÃÃCritical Reviews in Plant Sciences 11:121©134.ÄÄ ÃÃKEYWORDS: EXPOSURE METHODS, FACEÄÄ Ã Ã18Ä Ä° `  à ÃAllen, L.H., Jr., and S.E. Beladi.Ä Ä 1990. Free©Air CO2 Enrichment (FACE): Analysis of Gaseous Dispersion Arrays for the Study of Rising Atmospheric CO2 Effects on Vegetation. 1983©1989 Progress ReportÃÃ, 057 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. ÃÃKEYWORDS: EXPOSURE METHODS, FACEÄÄ Ã Ã19Ä Ä° `  à ÃAllen, L.H., Jr., E.C. Bisbal, K.J. Boote, and P.H. Jones.Ä Ä 1991. Soybean Dry Matter Allocation under Subambient and Superambient Levels of Carbon Dioxide. ÃÃAgronomy Journal 83:875©883.ÄÄ 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 [ÃÃGlycine maxÄÄ (L.) Merr.] dry matter production and allocation for two reasons: to assess response of plants to prehistoric as well as future 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 umol (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 components (petioles and stems) increased. At final harvest the respective [CO2] treatments resulted in 38, 53, 62, 100, 120 and 92% 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 increase plant growth, but also that plant growth was probably seriously limited by atmospheric [CO2] in preindustrial revolution times back to the previous global glaciation. soybean/Glycine max ÃÃKEYWORDS: ALLOCATION, GROWTH, PRE©INDUSTRIAL CO2 CONCENTRATION, SPAR UNITS, YIELDÄÄ Ã Ã20Ä Ä° `  à ÃAllen, L.H., Jr., E.C. Bisbal, W.J. Campbell, and K.J. Boote.Ä Ä 1990. Carbon Dioxide Effects on Soybean Developmental Stages and Expansive Growth. ÃÃSoil and Crop Science Society of Florida, Proceedings 49:124©131.ÄÄ 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 [ÃÃGlycine maxÄÄ (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. soybean/Glycine max ÃÃKEYWORDS: GROWTH, PHENOLOGY, PRE©INDUSTRIAL CO2 CONCENTRATION, SPAR UNITSÄÄ Ã Ã21Ä Ä° `  à ÃAllen, L.H., Jr., and K.J. Boote.Ä Ä 1992. Vegetation, Effect of Rising CO2. ÃÃIN: Encyclopedia of Earth System Science, Vol. 4, Academic Press, Inc., New York, pp. 409©416.ÄÄ ÃÃKEYWORDS: AIR POLLUTION, CLIMATE, NUTRITION, REVIEW, TEMPERATURE, TRANSPIRATIONÄÄ Ã Ã22Ä Ä° `  à ÃAllen, L.H., Jr., K.J. Boote, J.W. Jones, P.H. Jones, R.R. Valle, B. Acock, H.H. Rogers, and R.C. Dahlman.Ä Ä 1987. Response of Vegetation to Rising Carbon Dioxide: Photosynthesis, Biomass, and Seed Yield of Soybean. ÃÃGlobal Biogeochemical Cycles I:1©14.ÄÄ 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. soybean/Glycine max ÃÃKEYWORDS: CARBON CYCLE, CARBON SEQUESTERING, DEFORESTATION, GROWTH MODEL, PRE©INDUSTRIAL CO2 CONCENTRATION, REVIEWÄÄ Ã Ã23Ä Ä° `  à ÃAllen, L.H., Jr., K.J. Boote, J.W. Jones, J.W. Mishoe, P.H. Jones, R.R. Valle, and E.C. Bisbal.Ä Ä 1985. Subambient and Superambient Carbon Dioxide Effects on Growth, Nonstructural Carbohydrates, Biochemistry of Photosynthesis and Transpiration of Soybeans. 1984 Progress ReportÃÃ, 031 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CARBOHYDRATES, GROWTH, PHOTOSYNTHESIS, PRE©INDUSTRIAL CO2 CONCENTRATION, RIBULOSE BISPHOSPHATE CARBOXYLASE, SPAR UNITS, TRANSPIRATIONÄÄ Ã Ã24Ä Ä° `  à ÃAllen, L.H., Jr., K.J. Boote, J.W. Jones, J.W. Mishoe, P.H. Jones, C.V. Vu, R. Valle, and W.J. Campbell.Ä Ä 1982. Effects of Increased Carbon Dioxide on Photosynthesis and Agricultural Productivity of Soybeans. 1981 Progress ReportÃÃ, 003 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CARBOHYDRATES, CONDUCTANCE, GROWTH, GROWTH STAGES, NITROGEN, RIBULOSE BISPHOSPHATE CARBOXYLASE, SPAR UNITS, YIELDÄÄ Ã Ã25Ä Ä° `  à ÃAllen, L.H., Jr., K.J. Boote, J.W. Jones, J.W. Mishoe, P.H. Jones, C.V. Vu, R.R. Valle, W.J. Campbell, P.R. Harris, and K.F. Heimburg.Ä Ä 1984. Effects of Increased Carbon Dioxide and Water Stress Interactions on Photosynthesis, Transpiration, and Productivity of Soybeans. 1983 Progress ReportÃÃ, 014 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. soybean/Glycine max ÃÃKEYWORDS: CI:CA, GROWTH, LEAF PHOTOSYNTHESIS, PHOTOSYNTHETIC ACCLIMATION, SPAR UNITS, TRANSPIRATION, WATER STRESS, WUE, YIELDÄÄ Ã Ã26Ä Ä° `  à ÃAllen, L.H., Jr., B.G. Drake, H.H. Rogers, and J.H. Shinn.Ä Ä 1992. Field Techniques for Exposure of Plants and Ecosystems to Elevated CO2 and Other Trace Gases. ÃÃCritical Reviews in Plant Sciences 11:85©119.ÄÄ ÃÃKEYWORDS: EXPOSURE METHODS, REVIEW, SCALINGÄÄ Ã Ã27Ä Ä° `  à ÃAllen, L.H., Jr., R.R. Valle, J.W. Mishoe, J.W. Jones, and P.H. Jones.Ä Ä 1990. Soybean Leaf Gas Exchange Responses to CO2 Enrichment. ÃÃSoil and Crop Science Society of Florida, Proceedings 49:192©198.ÄÄ Carbon dioxide concentration of the atmosphere is expected to double within the next century. This study was undertaken to determine the leaf gas exchange responses of soybean (ÃÃGlycine MaxÄÄ (L.) Merr. cv. Bragg) grown continuously at 330, 450, 600, and 800 L (CO2)/million L (air), or volume parts per million volumes (vpm), in sunlit, controlled©environment chambers. The chambers were secured to soil bins filled with a reconstructed profile of Arredondo fine sand (a loamy siliceous hyperthermic Grossarenic Paleudult). A gas exchange system was used to measure leaf and air temperatures, flow rates, cuvette input and exit CO2 concentrations and vapor pressures, and incident solar photosynthetically active radiation (PAR). These measurements were used to calculate the carbon dioxide exchange rate (CER), transpiration rate (TRATE), stomatal resistance (rs), and leaf internal airspace (intercellular) CO2 concentration (Ci) of fully expanded, sunlit leaves held in a flat, horizontal position. Results indicated that leaf CER increased linearly over the CO2 concentration range of 330 to 800 vpm. Differences in leaf transpiration rates between the 800 and 330 vpm CO2 treatment were small. Water©use efficiency, CER/TRATE, increased as CO2 level increased, mainly due to an increase in CER. Both leaf stomatal resistance and leaf temperature increased with increasing CO2 concentrations at fixed PAR. The ratio of Ci to external CO2 concentration (Ce) was approximately constant across the range of [CO2] treatments. These findings showed no tendency for CO2©saturation of soybean leaf CER (and hence no evidence of CO2©induced feedback inhibition of photosynthetic rate) over the CO2 concentration range of 330 to 800 vpm. soybean/Glycine max ÃÃKEYWORDS: CI:CA, LEAF PHOTOSYNTHESIS, PHOTOSYNTHETIC FEEDBACK INHIBITION, SPAR UNITS, TRANSPIRATION, WUEÄÄ Ã Ã28Ä Ä° `  à ÃAllen, L.H., Jr., J.C.V. Vu, R.R. Valle, K.J. Boote, and P.H. Jones.Ä Ä 1988. Nonstructural Carbohydrates and Nitrogen of Soybean Grown under Carbon Dioxide Enrichment. ÃÃCrop Science 28:84©94.ÄÄ 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 [ÃÃGlycine maxÄÄ (L.) Merr. cv. Bragg]. Plants were grown at Gainesville, FL from seed to maturity in six sunlit, controlled©environment chambers that maintained CO2 at 330, 330, 450, 600, 800, and 800 umol (CO2)/mol (air). Attached lysimeters contained Arredondo fine sand (loamy, siliceous, hyperthermic Grossarenic Paleudult). Leaflet blades were sampled five times per day at 48 and 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. soybean/Glycine max ÃÃKEYWORDS: ALLOCATION, CARBOHYDRATES, NITROGEN, SPAR UNITS, SPECIFIC LEAF WEIGHTÄÄ Ã Ã29Ä Ä° `  à ÃAllen, S.G., S.B. Idso, and B.A. Kimball.Ä Ä 1990. Interactive Effects of CO2 and Environment on Net Photosynthesis of Water©Lily. ÃÃAgriculture, Ecosystems and Environment 30:81©88.ÄÄ Water©lily (ÃÃNymphaea marliacÄÄ) 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©33.2À$ÀC 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. Nymphaea marliac/water lily ÃÃKEYWORDS: AQUATIC PLANTS, CANOPY PHOTOSYNTHESIS, LIGHT, OPEN©TOP CHAMBERS, TEMPERATUREÄÄ Ã Ã30Ä Ä° `  à ÃAllen, S.G., S.B. Idso, B.A. Kimball, and M.G. Anderson.Ä Ä 1988. Relationship between Growth Rate and Net Photosynthesis of ÃÃAzollaÄÄ in Ambient and Elevated CO2 Concentrations. ÃÃAgriculture, Ecosystems and Environment 20:137©141.ÄÄ ÃÃAzolla pinnataÄÄ was grown out©of©doors at Phoenix, AZ, U.S.A. in open©topped plastic©walled chambers supplied with either 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 CO2 concentration©environment interaction. Azolla pinnata ÃÃKEYWORDS: AQUATIC PLANTS, CANOPY PHOTOSYNTHESIS, GROWTH RATE, OPEN©TOP CHAMBERSÄÄ Ã Ã31Ä Ä° `  à ÃAllen, S.G., S.B. Idso, B.A. Kimball, J.T. Baker, L.H. Allen Jr., J.R. Mauney, J.W. Radin, and M.G. Anderson.Ä Ä 1990. Effects of Air Temperature on Atmospheric CO2©Plant Growth RelationshipsÃÃ, TR048 in Yellow Report Series, DOE/ER©0450T, Dept. of Energy, Carbon Dioxide Research ProgramÄÄ. NTIS, U.S. Dept. of Commerce, Springfield, Virginia. ÃÃKEYWORDS: CARBOHYDRATES, CONDUCTANCE, PHENOLOGY, PHOTOSYNTHESIS, REVIEW, TEMPERATURE, YIELDÄÄ Ã Ã32Ä Ä° `  à ÃAlpert, P., F.R. Warembourg, and J. Roy.Ä Ä 1992. Transport of Carbon among Connected Ramets of ÃÃEichhornia crassipesÄÄ (Pontederiaceae) at Normal and High Levels of CO2. ÃÃAmerican Journal of Botany 78:1459©1466.ÄÄ The floating stoloniferous plant, ÃÃEichhornia crassipesÄÄ, has high rates of productivity and rapidly invades new sites. 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 ÃÃE. CrassipesÄÄ. Because net photosynthesis of ÃÃE. CrassipesÄÄ is significantly higher at high levels of atmospheric CO2, we also asked if high CO2 can change patterns of carbon transport in ways that might 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 offspring 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 as 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. ÃÃE. crassipesÄÄ maintains bidirectional transport of carbon between ramets even under uniform and favorable environmental conditions and when external CO2 levels are very high. Eichhornia crassipes/water hyacinth ÃÃKEYWORDS: 14C, AQUATIC PLANTS, ASSIMILATE EXPORT, CARBON BUDGET, GREENHOUSE, HYDROPONIC CULTURE, VEGETATIVE REPRODUCTIONÄÄ Ã Ã33Ä Ä° `  à ÃAlscher, G., and H. Krug.Ä Ä 1989. On©line Control of CO2 Enrichment in Protected Cultivation. ÃÃActa Horticulturae 248:321©327.ÄÄ As a base for experiments on CO2 on©line control the CO2 fluxes in greenhouses are simulated and potential control strategies 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 differences 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. lettuce/Lactuca sativa ÃÃKEYWORDS: CO2 MEASUREMENT AND CONTROL, COMMERCIAL USE OF CO2, GREENHOUSE, INTERMITTENT ENRICHMENT, SIMULATIONÄÄ Ã Ã34Ä Ä° `  à ÃAmthor, J.S.Ä Ä 1991. Respiration in a Future, Higher©CO2 World. ÃÃPlant, Cell and Environment 14:13©20.ÄÄ 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' respiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO2] independent of an increase in temperature. Literature pertaining to an impact of [CO2] on respiration rate is reviewed. With an increase in [CO2], respiration rate is increased in some cases, but decreased in others. The effects of [CO2] on respiration rate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms relate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) composition of phytomass, (4) direct chemical interactions between CO2 and respiratory enzymes, (5) direct chemical interactions between CO2 and other cellular components, (6) dark CO2 fixation rate, and (7) ethylene biosynthesis rate. Because a range of (possibly interactive) effects exists, and present knowledge is limited, the impact of future [CO2] on respiration rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined. ÃÃKEYWORDS: CARBON BUDGET, RESPIRATION, REVIEWÄÄ Ã Ã35Ä Ä° `  à ÃAmthor, J.S., G.W. Koch, and A.J. Bloom.Ä Ä 1992. CO2 Inhibits Respiration in Leaves of ÃÃRumex crispusÄÄ L. ÃÃPlant Physiology 98:757©760.ÄÄ Curly dock (ÃÃRumex crispusÄÄ L.) was grown from seed in a glasshouse at an ambient CO2 partial pressure of about 35 pascals. Apparent respiration rate (CO2 efflux in the dark) of expanded leaves was then measured at ambient CO2 partial pressure 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 pressure of CO2 typically inhibited respiration by 25 to 30%, whereas a decrease in CO2 elicited a corresponding increase in respiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO2 (a byproduct of respiration) and some component(s) of heterotrophic metabolism is indicated. Rumex crispus/curly dock ÃÃKEYWORDS: CI:CA, GREENHOUSE, RESPIRATIONÄÄ Ã Ã36Ä Ä° `  à ÃAnderson, I.H., C. Dons, S. Nilsen, and M.K. Haugstad.Ä Ä 1985. Growth, Photosynthesis and Photorespiration of ÃÃLemna gibbaÄÄ: Response to Variations in CO2 and O2 Concentrations and Photon Flux Density. ÃÃPhotosynthesis Research 6:87©96.ÄÄ Dry weight and Relative Growth Rate of ÃÃLemna gibbaÄÄ were significantly increased by CO2 enrichment up to 6000 uL CO2/L. This high CO2 optimum for growth is probably due to the presence of nonfunctional stomata. The response to high CO2 was less or absent following four days growth in 2% O2. The Leaf Area Ratio decreased in response to CO2 enrichment as a result of an increase in dry weight per frond. Photosynthetic rate was increased by CO2 enrichment up to 1500 uL CO2/L during measurement, showing only small increases with further CO2 enrichment up to 5000 uL CO2/L at a photon flux density of 210 umol/m2/s and small decreases at 2000 umol/m/s. The actual rate of photosynthesis of those plants cultivated at high CO2 levels, however, was less than the air grown plants. The response of photosynthesis to O2 indicated that the enhancement of growth and photosynthesis by CO2 enrichment was a result of decreased photorespiration. Plants cultivated in low O2 produced abnormal morphological features and after a short time showed a reduction in growth. Lemna gibba/duckweed ÃÃKEYWORDS: AQUATIC PLANTS, CANOPY PHOTOSYNTHESIS, CONTROLLED ENVIRONMENT CHAMBERS, GROWTH, LIGHT, OXYGEN, RESPIRATIONÄÄ Ã Ã37Ä Ä° `  à ÃAndersson, N.E.Ä Ä 1991. The Influence of Constant and Diurnally Changing CO2 Concentrations on Plant Growth and Development. ÃÃJournal of Horticultural Science 66:569©574.ÄÄ Plants of ÃÃFicus benjaminaÄÄ and miniature rose (ÃÃRosa hybridaÄÄ cv. Red Minimo) were grown under four CO2 treatments. Two had constant CO2 levels (600 and 900 ppm) and the other two had diurnal changes in CO2 levels, one increasing from 600 to 1500 ppm and one decreasing from 1500 to 600 ppm, each in four steps of 300 ppm during the day©time. In all treatments 900 ppm CO2 was maintained during the night when supplementary light was used, except in the treatment with constant 600 ppm where 600 ppm was also continued throughout the night. Plant growth was monitored under both decreasing and increasing natural daylength and irradiance. The tallest plants and greatest increment in height for ÃÃFicusÄÄ occurred with plants grown under constant CO2 concentration at 900 ppm. In both experiments with miniature roses the number of flower buds was significantly 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. Ficus benjamina/Rosa hybrida ÃÃKEYWORDS: COMMERCIAL USE OF CO2, DIURNAL CYCLE, FLOWER PRODUCTION, FLOWERING, GREENHOUSE, HORTICULTURAL CROPSÄÄ Ã Ã38Ä Ä° `  à ÃAndre, M., F. Cotte, A. Gerbaud, D. Massimino, J. Massimino, and C. Richaud.Ä Ä 1989. Effect of CO2 and O2 on Development and Fructification of Wheat in Closed Systems. ÃÃAdvances in Space Research 9:(8)17©(8)28.ÄÄ The cultivation of wheat (ÃÃTriticum aestivumÄÄ L.) was performed in controlled environment chambers with the continuous monitoring of photosynthesis, dark respiration, transpiration and main nutrient uptakes. A protocol in twin chambers was developed to compare the specific effects of low O2 and high CO2. Each parameter is able to influence photosynthesis but different effects are obtained in the development, fructification and seed production, because of the different effects of each parameter on the ratio of reductive to oxidative cycle of carbon. The first main conclusion is that low level of O2, at the same rate of biomass production, strongly acts on the rate of ear appearance and on seed production. Ear appearance was delayed and seed production reduced with a low O2 treatment (about 4%). The O2 effect was not mainly due to the repression of the oxidative cycle. The high CO2 treatment (700 to 900 uL/L) delayed ear appearance by 4 days, but did not reduce 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. Triticum aestivum/wheat ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CONTROLLED ENVIRONMENT CHAMBERS, OXYGEN, RESPIRATION, SEED PRODUCTIONÄÄ Ã Ã39Ä Ä° `  à ÃAndre, M., and H. Du Cloux.Ä Ä 1993. Interaction of CO2 Enrichment and Water Limitations on Photosynthesis and Water©Use Efficiency in Wheat. ÃÃPlant Physiology and Biochemistry 31:103©112.ÄÄ Wheat plants (ÃÃTriticum aestivumÄÄ L. cv. Capitole) were grown in twin closed growth chambers with continuous monitoring of CO2 and water exchanges. During the vegetative stage the effect of CO2 enrichment, from 330 to 660 uL/L, was studied under an irradiance of 660 uE/m2/s with an optimum watering. Comparisons were made with successive experiments in which daily water supply was fixed to a fraction (0.62©0.5©0.25) of the maximal transpiration of previous experiments. In a well watered canopy, the doubling of CO2 decreased transpiration by only 8%. Water use efficiency was increased (factor 1.45) mainly by the stimulation of photosynthesis. Under restricted water supply, photosynthesis of plants was more limited than transpiration. The inhibition of photosynthesis and the increase of water use efficiency can be predicted by a simple diffusion model applied to the response curve of photosynthesis to CO2, measured on canopy in standard conditions of watering. The main hypothesis is that the equivalent stomatal conductance is reduced proportionally to the water availability, without closure by patching. Under enriched CO2, the same reduction of leaf surface by water limitation was observed. Photosynthesis was less affected. Therefore, water use efficiency was again increased. Doubling CO2 concentration can compensate for water stress inhibition on CO2 assimilation. That model also predicts interactions of CO2 and water stress observed on water©use©efficiency which was increased by a factor up to 5 in comparison with well©watered plants in standard atmosphere. The implications of this study on global change models are discussed. wheat/Triticum aestivum ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CONDUCTANCE, CONTROLLED ENVIRONMENT CHAMBERS, GRASSES, PHOTOSYNTHESIS MODEL, TRANSPIRATION, WATER STRESS, WUEÄÄ Ã Ã40Ä Ä° `  à ÃAndre, M., H. Du Cloux, and C. Richaud.Ä Ä 1986. Wheat Response to CO2 Enrichment: CO2 Exchanges, Transpiration and Mineral Uptakes. ÃÃIN: Controlled Ecological Life Support System: CELLS '85 Workshop, 1985 July 16©19, NASA Report TM88215 (R. MacElroy, N.V. Martello, and D. Smernoff, eds.), AMES Research Center, Moffett Field, California, pp. 405©428.ÄÄ wheat/Triticum aestivum ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CONTROLLED ENVIRONMENT CHAMBERS, GROWTH ANALYSIS, NITROGEN, NUTRITION, PHOSPHORUS, PLANT DENSITY, POTASSIUM, TRANSPIRATION, WATER STRESS, WUEÄÄ Ã Ã41Ä Ä° `  à ÃAndre, M., H. Ducloux, C. Richaud, D. Massimino, A. Daguenet, J. Massimino, and A. Gerbaud.Ä Ä 1987. Etude des Relations entre Photosynthese Respiration, Transpiration et Nutrition Minerale chez le Ble. ÃÃAdvances in Space Research 7:(4)105©(4)114.ÄÄ La croissance du Ble ÃÃTriticum aestivumÄÄ 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 prÀ)Àsentera 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. wheat/Triticum aestivum ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CONTROLLED ENVIRONMENT CHAMBERS, NITROGEN, NUTRITION, PHOSPHORUS, POTASSIUM, RESPIRATION, TRANSPIRATIONÄÄ Ã Ã42Ä Ä° `  à ÃAndreeva, T.F., L.E. Strogonova, S.Y. Voevudskaya, S.N. Maevskaya, and N.N. Cherkanova.Ä Ä 1989. Effect of Enhanced CO2 Concentration on Photosynthesis, Carbohydrate and Nitrogen Metabolism, and Growth Processes in Mustard Plants. ÃÃFiziologiya Rastenii 36:40©48.ÄÄ 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 (ÃÃBrassica junceaÄÄ 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 27À$À/24À$À). Starch content increases significantly in plants grown under conditions of reduced temperature compared with ones grown at a higher temperature (34.4% of leaf dry mass at 20À$À/17À$À as compared with 20.1% at 32À$À/27À$À). 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. mustard/Brassica juncea ÃÃKEYWORDS: CARBOHYDRATES, CONTROLLED ENVIRONMENT CHAMBERS, FRACTION 1 PROTEIN, NITROGEN, PHOTOSYNTHESIS, TEMPERATUREÄÄ Ã Ã43Ä Ä° `  à ÃApel, P.Ä Ä 1989. Influence of CO2 on Stomatal Numbers. ÃÃBiologia Plantarum (Praha) 3:72©74.ÄÄ 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. 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/corn ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, CULTIVAR RESPONSES, STOMATAL DENSITYÄÄ Ã Ã44Ä Ä° `  à ÃArnone, J.A., III.Ä Ä 1988. Photosynthesis, Carbon Allocation, and Nitrogen Fixation in Red Alder. ÃÃDoctoral Dissertation, Yale University, Dissertation Abstracts Vol.50:08©B, p.3244 (96 pp.)ÄÄ. 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 nodulation 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 nodulation, 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 over the course of the experiment. This occurred more rapidly in nodulated plants and was attributed to more rapid attainment 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. Alnus rubra/red alder ÃÃKEYWORDS: ALLOCATION, CARBON:NITROGEN RATIO, CONTROLLED ENVIRONMENT CHAMBERS, NITROGEN, NITROGEN FIXATION, TREESÄÄ Ã Ã45Ä Ä° `  à ÃArnone, J.A., III, and J.C. Gordon.Ä Ä 1990. Effect of Nodulation, Nitrogen Fixation and CO2 Enrichment on the Physiology, Growth and Dry Mass Allocation of Seedlings of ÃÃAlnus rubraÄÄ Bong. ÃÃNew Phytologist 116:55©66.ÄÄ Inoculated and uninoculated ÃÃAlnus rubraÄÄ Bong. seedlings were grown for 47 days in atmospheres containing ambient (350 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. Evidence 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. Alnus rubra ÃÃKEYWORDS: ALLOCATION, CONTROLLED ENVIRONMENT CHAMBERS, NITROGEN FIXATION, NODULATION, TREESÄÄ Ã Ã46Ä Ä° `  à ÃArp, W.J.Ä Ä 1991. Effects of Source©Sink Relations on Photosynthetic Acclimation to Elevated CO2. ÃÃPlant, Cell and Environment 14:869©875.ÄÄ 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. ÃÃKEYWORDS: PHOTOSYNTHETIC ACCLIMATION, POT VOLUME, REVIEW, ROOT:SHOOT RATIO, SOURCE©SINK BALANCEÄÄ Ã Ã47Ä Ä° `  à ÃArp, W.J.Ä Ä 1991. Vegetation of a North American Salt Marsh and Elevated Atmospheric Carbon Dioxide. ÃÃDoctoral Dissertation, Centrale Huisdrukkerij Vrije Universiteit, AmsterdamÄÄ. Distichlis spicata/Spartina patens/Scirpus olneyi ÃÃKEYWORDS: C3, C4, EVAPOTRANSPIRATION, GROWTH, HALOPHYTES, LEAF PHOTOSYNTHESIS, OPEN©TOP CHAMBERS, PHOTOSYNTHETIC ACCLIMATION, SALT MARSH, SOURCE©SINK BALANCE, SPECIES COMPETITION, WATER STATUSÄÄ Ã Ã48Ä Ä° `  à ÃArp, W.J., and B.G. Drake.Ä Ä 1991. Increased Photosynthetic Capacity of ÃÃScirpus olneyiÄÄ after 4 Years of Exposure to Elevated CO2. ÃÃPlant, Cell and Environment 14:1003©1006.ÄÄ 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 observed in other species growing in the field, which suggests that photosynthesis of certain field grown plants will continue to respond to elevated levels of atmospheric CO2. sedge/Scirpus olneyi ÃÃKEYWORDS: LEAF PHOTOSYNTHESIS, OPEN©TOP CHAMBERS, PHOTOSYNTHETIC ACCLIMATIONÄÄ Ã Ã49Ä Ä° `  à ÃArp, W.J., B.G. Drake, W.T. Pockman, P.S. Curtis, and D.F. Whigham.Ä Ä 1993. Interactions between C3 and C4 Salt Marsh Plant Species during Four Years of Exposure to Elevated Atmospheric CO2. ÃÃVegetatio 104/105:133©143.ÄÄ Elevated atmospheric CO2 is known to stimulate photosynthesis and growth of plants with the C3 pathway but less of plants 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 CO2/mol) on a salt marsh vegetation with both C3 and C4 species was investigated. Elevated CO2 increased the biomass of the C3 sedge ÃÃScirpus olneyiÄÄ growing in a pure stand, while the biomass of the C4 grass ÃÃSpartina patensÄÄ in a monospecific community 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 ÃÃSpartina patensÄÄ dominated the higher areas of the salt marsh, while the C3 sedge ÃÃScirpus olneyiÄÄ was most abundant at the lower elevations, and the mixed community occupied intermediate elevations. ÃÃScirpusÄÄ growth may have been restricted by drought and salt stress at the higher elevations, while ÃÃSpartinaÄÄ growth at the lower elevations may be affected by the higher frequency of flooding. Elevated CO2 may affect the species distribution in the salt marsh if it allows ÃÃScirpusÄÄ to grow at higher elevations where it in turn may affect the growth of ÃÃSpartinaÄÄ. Spartina patens/Scirpus olneyi/Distichlis spicata ÃÃKEYWORDS: AQUATIC PLANTS, C3, C4, COMMUNITY LEVEL CO2 RESPONSES, GROWTH, HALOPHYTES, OPEN©TOP CHAMBERS, SALT MARSH, SALT STRESS, SPECIES COMPETITION, WATER STRESSÄÄ Ã Ã50Ä Ä° `  à ÃArtus, N.N.Ä Ä 1990. Two Mutants of ÃÃArabidopsis thalianaÄÄ That Become Chlorotic in Atmospheres Enriched with CO2. ÃÃPlant, Cell and Environment 13:575©580.ÄÄ Two nonallelic, nuclear recessive mutants of ÃÃArabidopsis thalianaÄÄ (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 leaves and spreads to the tips. The injurious effects of CO2 seem to be restricted to photosynthetic tissues, since root elongation 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 mutations do not impose a requirement for photorespiration. The possibilities that the high CO2©sensitive phenotypes are caused by an effect of CO2 in stomata, on ethylene synthesis, or on mineral uptake are discussed but are considered unlikely. Arabidopsis thaliana ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, MUTANTÄÄ Ã Ã51Ä Ä° `  à ÃAshenden, T.W., R. Baxter, and C.R. Rafarel.Ä Ä 1992. An Inexpensive System for Exposing Plants in the Field to Elevated Concentrations of CO2. ÃÃPlant, Cell and Environment 15:365©372.ÄÄ An inexpensive, potentially mobile field exposure system is described which may be easily constructed by a small workshop. 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 relatively 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. ÃÃKEYWORDS: EXPOSURE METHODS, OUTDOOR GROWTH CHAMBERSÄÄ Ã Ã52Ä Ä° `  à ÃAston, A.R.Ä Ä 1984. The Effect of Doubling Atmospheric CO2 on Streamflow: a Simulation. ÃÃJournal of Hydrology 67:273©280.ÄÄ There is a potential for atmospheric CO2 to rise four© or six©fold, and at some time in the foreseeable future a doubling 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. ÃÃKEYWORDS: HYDROLOGIC MODEL, STREAMFLOWÄÄ Ã Ã53Ä Ä° `  à ÃAustin, M.P.Ä Ä 1992. Modelling the Environmental Niche of Plants: Implications for Plant Community Response to Elevated CO2 Levels. ÃÃAustralian Journal of Botany 40:615©630.ÄÄ 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, forest modellers using FORET type models, a symmetric curve, and community ecologists a skewed response with a tail towards high 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 ÃÃEucalyptus fastigataÄÄ for 8377 sites in southern New South Wales, Australia. Seven environmental variables or factors are considered: mean annual temperature, mean annual rainfall, mean monthly solar radiation, topographic position, rainfall seasonality, lithology, and soil; nutrient status. The temperature response is modelled by a ÃÃBetaÄÄ©function, log ÃÃy + a + alphaÄÄ log ÃÃ(t © a) + sigmaÄÄ log ÃÃ(b © t)ÄÄ, where ÃÃtÄÄ is temperature and letters are parameters. The probability of occurrence is shown to be a skewed function 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. Eucalyptus fastigata ÃÃKEYWORDS: COMMUNITY LEVEL CO2 RESPONSES, ENVIRONMENTAL INTERACTIONS, FOREST, MODELING, NICHE THEORY, SPECIES RANGEÄÄ Ã Ã54Ä Ä° `  à ÃBadger, M.Ä Ä 1992. Manipulating Agricultural Plants for a Future High CO2 Environment. ÃÃAustralian Journal of Botany 40:421©429.ÄÄ 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 temperatures, resulting from the improvement which will occur in the performance of the primary carboxylating enzyme, Rubisco. However, while growth experiments at elevated CO2 indicate that C3 plants show stimulation of dry matter accumulation, the potential gains are greatly ameliorated by a redistribution of plant resources. This primarily occurs via a reduction in the leaf area ratio which offsets increases in the net assimilation rate. In addition, there may be an overcommitment of nitrogen in key photosynthetic components such as Rubisco and the thylakoid electron transport system. It is concluded that plants 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 elevated CO2 include (1) altering source©sink relations; (2) improving the redistribution of nitrogen between the photosynthetic machinery and the rest of the plant; and (3) changing the response of stomata to CO2 and humidity to increase water©use efficiency even further than is currently predicted. ÃÃKEYWORDS: AGRICULTURE, C3, C4, ENVIRONMENTAL INTERACTIONS, GROWTH ANALYSIS, LIGHT, NITROGEN, PHENOLOGY, REVIEW, RIBULOSE BISPHOSPHATE CARBOXYLASE, SOURCE©SINK BALANCE, TEMPERATURE, WUEÄÄ Ã Ã55Ä Ä° `  à ÃBaille, A.Ä Ä 1989. Greenhouse Microclimate and Its Management in Mild Winter Climates. ÃÃActa Horticulturae 246:23©36.ÄÄ ÃÃKEYWORDS: GREENHOUSEÄÄ Ã Ã56Ä Ä° `  à ÃBailly, J., and J.R. Coleman.Ä Ä 1988. Effect of CO2 Concentration on Protein Biosynthesis and Carbonic Anhydrase Expression in ÃÃChlamydomonas reinhardtiiÄÄ. ÃÃPlant Physiology 87:833©840.ÄÄ The effect of external inorganic carbon (Ci) concentrations on protein biosynthesis and carbonic anhydrase (CA) mRNA abundance were examined in the eukaryotic alga ÃÃChlamydomonas reinhardtiiÄÄ. Transfer of high CO2 (5%) grown algae to air levels of CO2 resulted in the transitory synthesis of two polypeptides of approximately 49,000 and 52,000 daltons as well as prolonged synthesis and accumulation of the 37,000 dalton CA monomer and an unidentified 20,000 dalton polypeptide. The gene coding for carbonic anhydrase was isolated from a genomic expression library and subjected to restriction endonuclease analysis. Southern blot analysis of chromosomal DNA indicates that only a single copy of the gene is present. The 2.5 kilobase DNA fragment hybridizes specifically to a 1.4 kilobase transcript in RNA isolated from air©grown cells and from cells grown on 5% CO2 that have been exposed to air levels of CO2. Maximum mRNA abundance was observed after 1 to 3 hours of exposure to air. Transfer of air©grown cells to a high CO2 environment resulted in the elimination of the CA transcript after 60 minutes of exposure. Changes in CA transcript abundance in response to external Ci concentrations occurred in the presence or absence of light. Chlamydomonas reinhardtii ÃÃKEYWORDS: ALGAE, AQUATIC PLANTS, CARBONIC ANHYDRASE, CELL CULTURE, ENZYMES, GENE EXPRESSIONÄÄ Ã Ã57Ä Ä° `  à ÃBaker, J.T., and L.H. Allen Jr.Ä Ä 1993. Contrasting Crop Species Responses to CO2 and Temperature: Rice, Soybean and Citrus. ÃÃVegetatio 104/105:239©260.ÄÄ The continuing increase in atmospheric carbon dioxide concentration ([CO2]) and projections of possible future increases in global air temperatures have stimulated interest in the effects of these climate variables on plants and, in particular, on agriculturally important food crops. Mounting evidence from many different experiments suggests that the magnitude and even direction of crop responses to [CO2] and temperature is almost certain to be species dependent and very likely, within a species, to be cultivar dependent. Over the last decade, [CO2] and temperature experiments have been conducted on several crop species in the outdoor, naturally©sunlit, environmentally controlled, plant growth chambers by USDA©ARS and the University of Florida, at Gainesville, Florida, USA. The objectives for this paper are to summarize some of the major findings of these experiments and further to compare and contrast species responses to [CO2] and temperature for three diverse crop species: rice (ÃÃOryza sativaÄÄ, L.), soybean (ÃÃGlycine maxÄÄ, L.) and citrus (various species). Citrus had the lowest growth and photosynthetic rates but under [CO2] enrichment displayed the greatest percentage increases over ambient [CO2] control treatments. In all three species the direct effect of [CO2] enrichment was always an increase in photosynthetic rate. In soybean, photosynthetic rate depended on current [CO2] regardless of the long©term [CO2] history of the crop. In rice, photosynthetic rate measured at a common [CO2], decreased with increasing long©term [CO2] growth treatment due to a corresponding decline in RuBP carboxylase content and activity. Rice specific respiration decrease from subambient to ambient and superambient [CO2] due to a decrease in plant tissue nitrogen content and a decline in specific maintenance respiration rate. In all three species, crop water use decreased with [CO2] enrichment but increased with increases in temperature. For both rice and soybean, [CO2] enrichment increased growth and grain yield. Rice grain yields declined by roughly 10% per each 1À$ÀC rise in day/night temperature above 28/21À$ÀC. rice/Oryza sativa/soybean/Glycine max/citrus/Citrus sinensis/Poncirus trifoliata ÃÃKEYWORDS: ENVIRONMENTAL INTERACTIONS, EVAPOTRANSPIRATION, NITROGEN, PHOTOSYNTHESIS, PHOTOSYNTHETIC ACCLIMATION, PRE©INDUSTRIAL CO2 CONCENTRATION, RESPIRATION, REVIEW, RIBULOSE BISPHOSPHATE CARBOXYLASE, TEMPERATURE, WUE, YIELDÄÄ Ã Ã58Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., and K.J. Boote.Ä Ä 1990. Growth and Yield Responses of Rice to Carbon Dioxide Concentration. ÃÃJournal of Agricultural Science, Cambridge 115:313©320.ÄÄ Rice plants (ÃÃOryza sativaÄÄ L., cv. IR30) were grown in paddy culture in outdoor, naturally sunlit, controlled©environment, plant growth chambers at Gainesville, Florida, USA, in 1987. The rice plants were exposed throughout the season to subambient (160 and 250), ambient (330) or superambient (500, 660, 900 umol CO2/mol air) CO2 concentrations. Total shoot biomass, root biomass, tillering, and final grain yield increased with increasing CO2 concentration, the greatest increase occurring between the 160 and 500 umol CO2/mol air treatments. Early in the growing season, root:shoot biomass ratio increased with increasing CO2 concentration; although the ratio decreased during the growing season, net assimilation rate increased with increasing CO2 concentration and decreased during the growing season. Differences in biomass and lamina area among CO2 treatments were largely due to corresponding differences in tillering response. The number of panicles/plant was almost entirely responsible for differences in final grain yield among CO2 treatments. Doubling the CO2 concentration from 330 to 660 umol CO2/mol air resulted in a 32% increase in grain yield. These results suggest that important changes in the growth and yield of rice may be expected in the future as the CO2 concentration of the earth's atmosphere continues to rise. rice/Oryza sativa ÃÃKEYWORDS: ALLOCATION, GROWTH ANALYSIS, PRE©INDUSTRIAL CO2 CONCENTRATION, SPAR UNITSÄÄ Ã Ã59Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., and K.J. Boote.Ä Ä 1992. Response of Rice to Carbon Dioxide and Temperature. ÃÃAgricultural and Forest Meteorology 60:153©166.ÄÄ The current increase in atmospheric carbon dioxide concentration ([CO2]) along with predictions of possible future increases in global air temperatures have stimulated interest in the effects of [CO2] and temperature on the growth and yield of food crops. This study was conducted to determine the effects and possible interactions of [CO2] and temperature on the growth and yield of rice (ÃÃOryza sativaÄÄ L., cultivar IR©30). Rice plants were grown for a season in outdoor, naturally sunlit, controlled©environment, and plant growth chambers. Temperature treatments of 28/21/25, 34/27/31, and 40/33/37À$ÀC (daytime dry bulb air temperature/night©time dry bulb air temperature/paddy water temperature) were maintained in [CO2] treatments of 330 and 660 umol CO2/mol air. In the 40/33/37À$ÀC temperature treatment, plants in the 330 umol/mol [CO2] treatment died during stem extension while the [CO2] enriched plants survived but produced sterile panicles. Plants in the 34/27/31À$ÀC temperature treatments accumulated biomass and leaf area at a faster rate early in the growing season than plants in the 28/21/25À$ÀC temperature treatments. Tillering increased with increasing temperature treatment. Grain yield increases owing to [CO2] enrichment were small and non©significant. This lack of [CO2] response on grain yield was attributed to the generally lower levels of solar irradiance encountered during the late fall and winter when this experiment was conducted. Grain yields were affected much more strongly by temperature than [CO2] treatment. Grain yields declined by an average of approximately 7©8% per 1À$ÀC rise in temperature from the 28/21/25 to 34/27/31À$ÀC temperature treatment. The reduced grain yields with increasing temperature treatment suggests potential detrimental effects on rice production in some areas if air temperatures increase, especially under conditions of low solar irradiance. rice/Oryza sativa ÃÃKEYWORDS: GROWTH, SPAR UNITS, TEMPERATURE, YIELDÄÄ Ã Ã60Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., and K.J. Boote.Ä Ä 1992. Temperature Effects on Rice at Elevated CO2 Concentration. ÃÃJournal of Experimental Botany 43:959©964.ÄÄ The continuing increase in atmospheric carbon dioxide concentration ([CO2]) and projections of possible future increases in global air temperatures have stimulated interest in the effects of these climate variables on agriculturally important food crops. This study was conducted to determine the effects of [CO2] and temperature on rice (ÃÃOryza sativaÄÄ L., cv. IR©30). Rice plants were grown season©long in outdoor, naturally sunlit, controlled©environment, plant growth chambers in temperature regimes ranging from 25/18/21À$ÀC to 37/30/34À$ÀC (daytime dry bulb air temperature/night©time dry bulb air temperature/paddy water temperature) and [CO2] of 660 umol CO2/mol air. An ambient chamber was maintained at a [CO2] of 330 umol/mol and temperature regime of 28/21/25À$ÀC. Carbon dioxide enrichment at 28/21/25À$ÀC increased both biomass accumulation and tillering and increased grain yield by 60%. In the 660 umol/mol [CO2] treatment, grain yield decreased from 10.4 to 1.0 Mg/ha with increasing temperature from 28/21/25À$ÀC to the 37/30/34À$ÀC temperature treatment. Across this temperature range, the number of panicles/plant nearly doubled while the number of seeds/panicle declined sharply. These results indicate that while future increase in atmospheric [CO2] are likely to be beneficial to rice growth and yield, potentially large negative effects on rice yield are possible if air temperatures also rise. rice/Oryza sativa ÃÃKEYWORDS: GROWTH, SEED PRODUCTION, SPAR UNITS, TEMPERATURE, YIELDÄÄ Ã Ã61Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., K.J. Boote, P. Jones, and J.W. Jones.Ä Ä 1989. Response of Soybean to Air Temperature and Carbon Dioxide Concentration. ÃÃCrop Science 29:98©105.ÄÄ Documented increases in global atmospheric CO2 concentration have stimulated interest in the direct effects of CO2 on plant growth and yield as well as the interactive effects of CO2 with other major climatic variables. This study was conducted to determine the effects and interactions of CO2 concentration and air temperature on the development, growth, total nonstructural carbohydrate (TNC), and final seed yield of soybean [ÃÃGlycine maxÄÄ (L.) Merr., cv. Bragg] grown season©long in naturally lit, controlled©environment chambers. Day/night air temperatures of 26/19, 31/24 and 36/29À$ÀC were maintained in CO2 treatments of 330 and 660 umol CO2/mol air. Both CO2 enrichment and increasing air temperature decreased main stem plastochron interval, while increasing air temperature increased final mainstem node number. Leaf area and above©ground biomass increased with CO2 enrichment and with temperature from 26/19À$ÀC to 31/24À$ÀC. The nonlinear increase with temperature in leaf area, aboveground biomass, and plastochron interval was attributed to the highest temperature treatment being near or above the optimum for soybean growth and development. Seed yield increased with CO2 enrichment due mainly to an increase in seed number rather than weight per seed. Individual seed weight decreased, while seed number increased with increasing temperature. Leaflet TNC was relatively stable throughout the day. Stem TNC was less affected by CO2 than by temperature treatment and decreased with increasing temperature. These results indicate that the response of soybean to elevated CO2 concentration is highly temperature dependent. soybean/Glycine max ÃÃKEYWORDS: CARBOHYDRATES, REPRODUCTION, SEEDS, SPAR UNITS, TEMPERATURE, YIELDÄÄ Ã Ã62Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., K.J. Boote, P. Jones, and J.W. Jones.Ä Ä 1990. Developmental Responses of Rice to Photoperiod and Carbon Dioxide Concentration. ÃÃAgricultural and Forest Meteorology 50:201©210.ÄÄ The documented increase in the carbon dioxide concentration of the Earth's atmosphere has stimulated interest in the effects of CO2 on plants and in particular the future prospects for the world's food supplies. While rice is a major food crop, relatively little is known about the effects of CO2 concentration on the timing of physiological growth stages and total growth duration, which are important aspects of a rice cultivar's adaptability to the environment of a particular geographic region. The objective of this study was to determine the developmental responses of a modern, improved rice cultivar (ÃÃOryza sativaÄÄ, cultivar 'IR©30') to a range of CO2 concentrations under two contrasting photoperiods. Rice plants were grown season©long in an outdoor, naturally lit, computer©controlled environment, plant growth chambers in CO2 concentrations of 160, 250 (subambient), 330 (ambient), 500, 660 and 900 (superambient) umol CO2/mol air. The entire experiment was conducted twice during 1987. The first or early planted rice (EPR) experiment was conducted with photoperiod extension lights during the vegetative phase of development, while the second or late©planted rice (LPR) experiment was conducted using only naturally occurring photoperiod. In both experiments, mainstem leaf developmental rates were greater during vegetative rather than reproductive growth stages and leaf appearance rates increased with CO2 treatment during vegetative development. In the LPR experiment, panicle initiation and boot stage occurred earlier and total growth duration was shortened for rice plants in the superambient compared with ambient and subambient CO2 treatments. This acceleration of plant development with increasing CO2 treatment was associated with a CO2©induced decrease in the number of mainstem leaves formed during the vegetative phase of growth. The reduced developmental response of rice plants to CO2 in the EPR compared with the LPR experiment was attributed to the artificially extended photoperiod during the EPR experiment forcing a delay in the onset of reproductive development particularly in the superambient treatments. The CO2©induced acceleration of development and shortening of total growth duration should become a topic of interest for rice agronomists and breeders involved with selecting rice cultivars and agronomic practices for a particular geographic region in view of the continued increases in global atmospheric CO2 concentration. rice/Oryza sativa ÃÃKEYWORDS: GROWTH STAGES, PHOTOPERIOD, PRE©INDUSTRIAL CO2 CONCENTRATION, SPAR UNITSÄÄ Ã Ã63Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., K.J. Boote, P. Jones, and J.W. Jones.Ä Ä 1990. Rice Photosynthesis and Evapotranspiration in Subambient, Ambient, and Superambient Carbon Dioxide Concentrations. ÃÃAgronomy Journal 82:834©840.ÄÄ The current global rise in atmospheric carbon dioxide concentration [CO2], has stimulated interest in the response of agricultural crops to [CO2]. The objectives were to determine the effects of [CO2] on photosynthesis, evapotranspiration, and water use efficiency of rice (ÃÃOryza sativaÄÄ L., cv. IR©30). Rice plants were grown in naturally sunlit, plant growth chambers in subambient (160 and 250), ambient (330), or superambient (500, 660, and 900 umol CO2/mol air) [CO2] treatments. Photosynthetic light response curves were analyzed to obtain estimates of canopy light utilization efficiency (ÀÀ) and canopy conductance to CO2 transfer (À)À). Estimates of ÀÀ increased with increasing [CO2] treatment with the greatest increase in the 160 to 500 umol/mol treatments. Estimates of À)À were more variable than those of ÀÀ and were not different among [CO2] treatments. Photosynthetic rates increased with increasing [CO2] treatment from 160 to 500 umol/mol followed by a leveling off of the response among the superambient [CO2] treatments. Evapotranspiration decreased while water©use efficiency increased with increasing [CO2]. Short©term cross©switching of [CO2] among the chambers revealed a profound adaptive response to long©term [CO2] growth treatment. The lack of further photosynthetic response above the 500 umol/mol [CO2] treatment appears to indicate a need to select or screen rice cultivars for increased response to superambient [CO2] in order to more fully take advantage of future increases in global atmospheric [CO2]. rice/Oryza sativa ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, LIGHT, PRE©INDUSTRIAL CO2 CONCENTRATION, SPAR UNITS, TRANSPIRATION, WUEÄÄ Ã Ã64Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., K.J. Boote, A.J. Rowland©Bamford, J.W. Jones, P.H. Jones, G. Bowes, and S.L. Albrecht.Ä Ä 1988. Response of Rice to Subambient and Superambient Carbon Dioxide Concentrations 1986©1987 Progress ReportÃÃ, 043 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. rice/Oryza sativa ÃÃKEYWORDS: ALLOCATION, ANABAENA VARIABILIS, CANOPY PHOTOSYNTHESIS, CARBOHYDRATES, CYANOBACTERIA, GROWTH STAGES, PRE©INDUSTRIAL CO2 CONCENTRATION, RIBULOSE BISPHOSPHATE CARBOXYLASE, SPAR UNITS, STOMATAL DENSITY, TRANSPIRATION, YIELDÄÄ Ã Ã65Ä Ä° `  à ÃBaker, J.T., L.H. Allen Jr., K.J. Boote, A.J. Rowland©Bamford, J.W. Jones, P.H. Jones, G. Bowes, and F. Laugel.Ä Ä 1989. Temperature and CO2 Effects on Rice. 1988 Progress ReportÃÃ, 053 in Green Report Series, Response of Vegetation to Carbon DioxideÄÄ. U.S. Dept. of Energy, Carbon Dioxide Research Division, and U.S. Dept. of Agriculture, Agric. Res. Serv., Washington, D.C. Oryza sativa/rice ÃÃKEYWORDS: CANOPY PHOTOSYNTHESIS, CARBOHYDRATES, EVAPOTRANSPIRATION, GROWTH STAGES, RESPIRATION, RIBULOSE BISPHOSPHATE CARBOXYLASE, SPAR UNITS, SUCROSEPHOSPHATE SYNTHASE, TEMPERATURE, YIELDÄÄ Ã Ã66Ä Ä° `  à ÃBaker, J.T., F. Laugel, K.J. Boote, and L.H. Allen Jr.Ä Ä 1992. Effects of Daytime Carbon Dioxide Concentration on Dark Respiration in Rice. ÃÃPlant, Cell and Environment 15:231©239.ÄÄ Rising atmospheric carbon dioxide concentration ([CO2]) has generated considerable interest in the response of agricultural crops to [CO2]. The objectives of this study were to determine the effects of a wide range of daytime [CO2] on dark respiration of rice (ÃÃOryza sativaÄÄ L. cv. IR©30). Rice plants were grown season©long in naturally sunlit plant growth chambers in subambient (160 and 250), ambient (330), or superambient (500, 660 and 900 umol CO2/mol air) [CO2] treatments. Canopy dark respiration, expressed on a ground area basis (Rd) increased with increasing [CO2] treatments and was very similar among the superambient treatments. The trends in Rd over time and in response to increasing daytime [CO2] treatment were associated with and similar to trends previously described for photosynthesis. Specific respiration rate (Rdw) decreased with time during the growing season and was higher in the subambient than the ambient and superambient [CO2] treatments. This greater Rdw in the subambient [CO2] treatments was attributed to a higher specific maintenance respiration rate and was associated with higher plant tissue nitrogen concentration. rice/Oryza sativa ÃÃKEYWORDS: NITROGEN, PRE©INDUSTRIAL CO2 CONCENTRATION, RESPIRATION, SPAR UNITSÄÄ Ã Ã67Ä Ä° `  à ÃBaker, R.G.E., and D.J. Boatman.Ä Ä 1990. Some Effects of Nitrogen, Phosphorus, Potassium and Carbon Dioxide Concentration on the Morphology and Vegetative Reproduction of ÃÃSphagnum cuspidatumÄÄ Ehrh. ÃÃNew Phytologist 116:604©611.ÄÄ Five experiments are described which were designed to investigate the effects of varying the concentrations of nitrate, phosphate, potassium and carbon dioxide in the culture solution on the morphology and vegetative reproduction of ÃÃSphagnum cuspidatumÄÄ Ehrh. The plants were grown axenically from spores sown on agar containing inorganic salts and then transferred to aqueous culture solutions through which air containing enhanced concentrations of carbon dioxide was passed. In three of the experiments the plants were grown in a balanced inorganic salt solution at various dilutions and in two of these the concentration of carbon dioxide in the gas bubbled through the solution was varied. The concentrations of nitrogen, phosphorus and potassium were varied independently and in combination in the remaining experiments while the concentration of carbon dioxide was kept constant. In some of the experiments the minimum concentrations of nitrogen and potassium supplied were considerably below the minimum average concentrations recorded in rain but the minimum concentration of phosphorus supplied was within the upper part of the range recorded in rain. Within the ranges supplied the concentrations of all three elements and of carbon dioxide affected interfascicle length and vegetative reproduction (innovation formation) but it was concluded that the element limiting innovation formation in natural conditions is phosphorus. Sphagnum cuspidatum ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, NITROGEN, NUTRITION, PHOSPHORUS, POTASSIUM, VEGETATIVE REPRODUCTIONÄÄ Ã Ã68Ä Ä° `  à ÃBaldocchi, D.D., R. White, and J.W. Johnston.Ä Ä 1989. A Wind Tunnel Study to Design Large, Open©top Chambers for Whole©tree Pollutant Exposure Experiments. ÃÃJournal of the Air Pollution Control Association 39:549©1556.ÄÄ A wind tunnel study was conducted to determine the optimal design features of a large, open©top chamber, as needed for pollution exposure studies on mature trees. An optimally©designed, open©top chamber must minimize the incursion of ambient air through its opening and maintain a uniform treatment concentration throughout the chamber. The design features of interest are the diameter and height of the chamber and the deflection angle and opening size of any frustum that may be mounted on top of a model chamber. Design specifications depend on the turbulence regime about the chamber, which is influenced by the nature of the surrounding vegetation. Consequently, our investigation was performed on scale©model, open©top chambers in a wind tunnel populated with a model coniferous forest. Turbulence measurements demonstrated the similarity between the turbulence regime of the model and a natural forest. A hydrocarbon tracer was injected into the wind tunnel flow to characterize chamber performance. The main design features of open©top chambers are the velocity of air exiting through the top and the relationship between the length scale of the turbulence and the diameter of the chamber opening. As exit velocities increase, the proportion of eddies with sufficient force to penetrate into the chamber decrease. Therefore, for equal volumetric air flows, smaller opening sizes increase the exit velocities and reduce the number and extent of ambient 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 reduced when the diameter of the chamber opening is smaller than the characteristic length scale of the turbulence, a measure 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 for a smoother transition in the wind velocity streamline and is less apt to cause wake turbulence, as is the case with steeper frusta. Knowledge of the turbulence characteristics of plant canopies are readily available in the literature and can aid scientists and engineers in designing the optimal chamber and frusta dimensions for their particular application. Therefore, the empirical approach to chamber design can be avoided, and substantial savings can be realized. ÃÃKEYWORDS: AIR POLLUTION, EXPOSURE METHODS, OPEN©TOP CHAMBERSÄÄ Ã Ã69Ä Ä° `  à ÃBall, M.C., and R. Munns.Ä Ä 1992. Plant Responses to Salinity under Elevated Atmospheric Concentrations of CO2. ÃÃAustralian Journal of Botany 40:515©525.ÄÄ This review explores effects of elevated CO2 concentrations on growth in relation to water use and salt balance of halophytic and non©halophytic species. Under saline conditions, the uptake and distribution of sodium and chloride must be regulated to protect sensitive metabolic sites from salt toxicity. Salt©tolerant species exclude most of the salt from the transpiration stream, but the salt flux from a highly saline soil is still considerable. To maintain internal ion concentrations within physiologically acceptable levels, the salt influx to leaves must match the capacities of leaves for salt storage and/or salt export by either retranslocation or secretion from glands. Hence the balance between carbon gain and the expenditure of water in association with salt uptake is critical to leaf longevity under saline conditions. Indeed, one of the striking features of halophytic vegetation, such as mangroves, is the maintenance of high water use efficiencies coupled with relatively low rates of water loss and growth. These low evaporation rates are further reduced under elevated CO2 conditions. This, with increased growth, leads to even higher water use efficiency. Leaves of plants grown under elevated CO2 conditions might be expected to contain lower salt concentrations than those grown under ambient CO2 if salt uptake is coupled with water uptake. However, salt concentrations in shoot tissues are similar in plants grown under ambient and elevated CO2 conditions despite major differences in water use efficiency. This phenomenon occurs in C3 halophytes and in both C3 and C4 non©halophytes. These results imply shoot/root communication in regulation of the salt balance to adjust to 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). ÃÃKEYWORDS: C3, C4, HALOPHYTES, REVIEW, SALT STRESSÄÄ Ã Ã70Ä Ä° `  à ÃBarlow, E.W.R., and J. Conroy.Ä Ä 1988. Influence of Elevated Atmospheric Carbon Dioxide on the Productivity of Australian Forestry Plantations. ÃÃIN: Greenhouse: Planning for Climate Change (G.I. Pearman, ed.), E.J. Brill, New York, pp. 520©533.ÄÄ Australia produced $2.7 billion worth of forest products in 1983©84 but a further $1.3 billion worth, principally softwood, were imported. Because of this ever increasing demand for softwood, there is a move away from utilization of native hardwoods and by 2020 AD, when the atmospheric CO2 concentration is likely to be greater than 450 ppmv, 75% of forest products are projected to come from coniferous plantations. This move towards ÃÃPinus radiataÄÄ 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. ÃÃPinus radiataÄÄ 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 response of pines to elevated CO2 at a range of phosphorus and water levels. When phosphorus was adequate, doubling CO2 concentration more than doubled the rate of photosynthesis and increased the total plant dry weight by about 40%. However, there 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 ÃÃP. radiataÄÄ may be altered due to a reduction in water use or an increase in the drought tolerance of the trees. We found that CO2 enrichment did not affect either of these factors but the water©use efficiency was increased when phosphorus was adequate. All families of ÃÃP. radiataÄÄ do not respond to CO2 enrichment in the same manner. In a study investigating the response of four families to elevated CO2 at two phosphorus levels, we have identified a considerable variation between the families in their response to CO2 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 ÃÃP. radiataÄÄ plantations. But this will only occur if phosphorus fertilization is adequate. If the rise in CO2 results in climatic change the range of ÃÃP. radiataÄÄ may be even further 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 phosphorus and water to enable more accurate prediction of the productivity and water use of Australian native forests and eucalyptus plantations. Pinus radiata ÃÃKEYWORDS: ALLOCATION, CONDUCTANCE, FAMILY RESPONSES, FOREST, GROWTH, LEAF PHOTOSYNTHESIS, NUTRITION, PHOSPHORUS, POT VOLUME, REVIEW, TREES, WATER STRESS, WUEÄÄ Ã Ã71Ä Ä° `  à ÃBaron, J.J., and S.F. Gorski.Ä Ä 1986. Response of Eggplant to a Root Environment Enriched with CO2. ÃÃHortScience 21:495©498.ÄÄ Several elevated concentrations of CO2 were injected into the root atmosphere to determine the influence of CO2 concentration in the soil on the growth of eggplant (ÃÃSolanum melongenaÄÄ L.). Elevated CO2 levels in the root atmosphere consistently increased stem diameter while a significant increase in plant total dry weight and leaf area only occurred during long day/warm temperature conditions. Under periods of short days and low light levels, 15% CO2 reduced total dry weight and leaf area. Applications of 14©CO2 to the root zone demonstrated that 14C eggplant roots absorb CO2 from the soil environment and translocate labeled compounds into the shoot. Solanum melongena/eggplant ÃÃKEYWORDS: 14C, FIZZ IRRIGATION, HORTICULTURAL CROPS, SOIL CO2 CONCENTRATIONÄÄ Ã Ã72Ä Ä° `  à ÃBarr, A.G., K.M. King, G.W. Thurtell, and M.E.D. Graham.Ä Ä 1990. Humidity and Soil Water Influence the Transpiration Response of Maize to CO2 Enrichment. ÃÃCanadian Journal of Plant Science 70:941©948.ÄÄ The impact of increasing atmospheric CO2 on the productivity of C4 crops may vary with soil water availability. This study investigates the hypothesis that elevating CO2 in ÃÃZea maysÄÄ L. reduces the degree to which transpiration is limited by soil water at high vapor pressure deficits or low soil water contents. Plants growing in controlled environments at 300 and 600 umol/mol CO2 were exposed daily to five levels of vapor pressure deficit as water was withheld and the soil dried over an 8©d period. Doubling CO2 caused an overall reduction of 23% in the transpiration rate and 34% in the leaf conductance, but the effect of CO2 on transpiration and leaf conductance was greatest at high soil water content and low vapor pressure deficit, when soil water least limited transpiration. Implications for the productivity of C4 crops in the field are discussed. corn/Zea mays ÃÃKEYWORDS: C4, CONDUCTANCE, CONTROLLED ENVIRONMENT CHAMBERS, HUMIDITY, TRANSPIRATION, VPD, WATER STRESSÄÄ Ã Ã73Ä Ä° `  à ÃBarson, M.M., and R.M. Gifford.Ä Ä 1990. Carbon Dioxide Sinks: The Potential Role of Tree Planting in Australia. ÃÃIN: Greenhouse and Energy (D.J. Swain, ed.), CSIRO, Australia, pp. 433©443.ÄÄ Reforestation has been suggested as a possible policy option at several recent international 'greenhouse effect' forums. 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. Although forestry cannot in principle offer a permanent solution to continuous emission of CO2 from fossil fuel burning, its expansion 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 sequestration 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. ÃÃKEYWORDS: MODELING, REFORESTATION, TREESÄÄ Ã Ã74Ä Ä° `  à ÃBauerle, W.L., D. Kretchman, and L. Tucker©Kelly.Ä Ä 1986. CO2 Enrichment in the U.S. ÃÃIN: Status and CO2 Sources, Vol. I (H.Z. Enoch and B.A. Kimball, eds.), Carbon Dioxide Enrichment of Greenhouse Crops, CRC Press, Inc., Boca Raton, Florida, pp. 49©57.ÄÄ ÃÃKEYWORDS: COMMERCIAL USE OF CO2, GREENHOUSEÄÄ Ã Ã75Ä Ä° `  à ÃBazzaz, F.A.Ä Ä 1990. The Response of Natural Ecosystems to the Rising Global CO2 Levels. ÃÃAnnual Review of Ecology and Systematics 21:167©196.ÄÄ ÃÃKEYWORDS: CO2 ENRICHMENT STUDIES, COMMUNITY LEVEL CO2 RESPONSES, ECOSYSTEM LEVEL CO2 RESPONSES, ENVIRONMENTAL INTERACTIONS, FAMILY RESPONSES, HERBIVORY, PHYSIOLOGICAL CO2 RESPONSES, POPULATION LEVEL CO2 RESPONSES, REVIEW, SOIL MICROORGANISMS, SPECIES COMPETITION, SPECIES RANGEÄÄ Ã Ã76Ä Ä° `  à ÃBazzaz, F.A., D.D. Ackerly, F.I. Woodward, and L. Rochefort.Ä Ä 1992. CO2 Enrichment and Dependence of Reproduction on Density in an Annual Plant and a Simulation of Its Population Dynamics. ÃÃJournal of Ecology 80:643©651.ÄÄ 1. Populations of an annual plant, ÃÃAbutilon theophrastiÄÄ, 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 of demography and reproduction. Variables measured included survivorship, proportion of plants flowering and fruiting, number 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 production 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 produced 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 simulated 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. Abutilon theophrasti ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, MODELING, OLD FIELD COMMUNITIES, PLANT DENSITY, POPULATION MODEL, REPRODUCTION, SIMULATION, SURVIVORSHIPÄÄ Ã Ã77Ä Ä° `  à ÃBazzaz, F.A., J.S. Coleman, and S.R. Morse.Ä Ä 1990. Growth Responses of Seven Major Co©occurring Tree Species of the Northeastern United States to Elevated CO2. ÃÃCanadian Journal of Forest Research 20:1479©1484.ÄÄ We examined how elevated CO2 affected the growth of seven co©occurring tree species: American beech (ÃÃFagus grandifoliaÄÄ Ehrh.), paper birch (ÃÃBetula papyriferaÄÄ Marsh.), black cherry (ÃÃPrunus serotinaÄÄ Ehrh.), white pine (ÃÃPinus strobusÄÄ L.), red maple (ÃÃAcer rubrumÄÄ L.), sugar maple (ÃÃAcer saccharumÄÄ Marsh.), and eastern hemlock (ÃÃTsuga canadensisÄÄ (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 from 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 pine, hemlock, sugar maple) under CO2 levels of 400 or 700 uL/L. Plants were then harvested for biomass and growth determinations. 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. Furthermore, 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 CO2 concentrations were the shade©tolerant species (i.e., beech, sugar maple, and hemlock). Thus, elevated CO2 levels may enhance 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 seedlings greatly affected their response to elevated CO2 concentration. 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 ÃÃKEYWORDS: CONTROLLED ENVIRONMENT CHAMBERS, GROWTH, SHADE TOLERANCE, SPECIES COMPETITION, TREESÄÄ Ã Ã78Ä Ä° `  à ÃBazzaz, F.A., and E.D. Fajer.Ä Ä 1992. Plant Life in CO2©Rich World. ÃÃScientific American 266:68©74.ÄÄ ÃÃKEYWORDS: C3, C4, CO2 ENRICHMENT STUDIES, ECOSYSTEM LEVEL CO2 RESPONSES, INSECTS, PHOTOSYNTHESIS, REVIEWÄÄ Ã Ã79Ä Ä° `  à ÃBazzaz, F.A., and K. Garbutt.Ä Ä 1988. The Response of Annuals in Competitive Neighborhoods: Effects of Elevated CO2. ÃÃEcology 69:937©946.ÄÄ Four members of an annual community were used to investigate the effects of changing neighborhood complexity and increased 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 moisture and high light. Species responded differently to enhanced CO2 level. Some species (e.g., ÃÃAbutilon theophrastiÄÄ) had increased biomass with increasing CO2, while others (e.g., ÃÃAmaranthus retroflexusÄÄ) 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 general, competitive arrays that had C3 species depressed the response of C4 species, especially ÃÃAmaranthusÄÄ. ÃÃAmbrosia artemisiifoliaÄÄ 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. Ambrosia artemisiifolia/Abutilon theophrasti/Amaranthus retroflexus/Setaria faberii ÃÃKEYWORDS: C3, C4, OLD FIELD COMMUNITIES, SPECIES COMPETITION, SUNLIT CONTROLLED ENVIRONMENT CHAMBERSÄÄ Ã Ã80Ä Ä° `  à ÃBazzaz, F.A., K. Garbutt, E.G. Reekie, and W.E. Williams.Ä Ä 1989. Using Growth Analysis to Interpret Competition between a C3 and a C4 Annual under Ambient and Elevated CO2. ÃÃOecologia 79:223©235.ÄÄ Detailed growth analysis in conjunction with information on leaf display and nitrogen uptake was used to interpret competition between ÃÃAbutilon theophrastiÄÄ, a C3 annual, and ÃÃAmaranthus retroflexusÄÄ, 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 other. Competition caused a reduction in growth in both species, but for different reasons. In ÃÃAbutilonÄÄ, decreases in leaf area ratio (LAR) were responsible, whereas decreased unit leaf rate (ULR) was involved in the case of ÃÃAmaranthusÄÄ. Mean canopy height was lower in ÃÃAmaranthusÄÄ than ÃÃAbutilonÄÄ which may explain the low ULR of ÃÃAmaranthusÄÄ in competition. The decrease in LAR of ÃÃAbutilonÄÄ was associated with an increase in root:shoot ratio implying that ÃÃAbutilonÄÄ was limited by competition for below ground resources. The root:shoot ratio of ÃÃAmaranthusÄÄ actually decreased with competition, and ÃÃAmaranthusÄÄ had a much higher rate of nitrogen uptake per unit of root than did ÃÃAbutilonÄÄ. These latter results suggest that ÃÃAmaranthusÄÄ was better able to compete for below ground resources than ÃÃAbutilonÄÄ. Although the growth of both species was reduced by competition, generally speaking, the growth of ÃÃAmaranthusÄÄ was reduced to a greater extent than that of ÃÃAbutilonÄÄ. Regression analysis suggests that the success of ÃÃAbutilonÄÄ in competition was due to its larger starting capital (seed size) which gave it an early advantage over ÃÃAmaranthusÄÄ. Elevated CO2 had a positive effect upon biomass in ÃÃAmaranthusÄÄ, and to a lesser extent, ÃÃAbutilonÄÄ. These effects were limited to the early part of the experiment in the case of the individually grown plants, however. Only ÃÃAmaranthusÄÄ 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. ÃÃAbutilonÄÄ grown in competition with ÃÃAmaranthusÄÄ had a greater final biomass than ÃÃAmaranthusÄÄ at ambient CO2 levels, but this difference disappeared to a large extent at elevated CO2. The high RGR of ÃÃAmaranthusÄÄ at elevated CO2 levels allowed it to overcome the difference in initial size between the two species. Abutilon theophrasti/Amaranthus retroflexus ÃÃKEYWORDS: C3, C4, GROWTH ANALYSIS, NITROGEN, OLD FIELD COMMUNITIES, ROOT:SHOOT RATIO, SPECIES COMPETITION, SUNLIT CONTROLLED ENVIRONMENT CHAMBERSÄÄ Ã Ã81Ä Ä° `  à ÃBazzaz, F.A., K. Garbutt, and W.E. Williams.Ä Ä 1985. Effect of Increased Atmospheric Carbon Dioxide Concentration on Plant Communities. ÃÃIN: Direct Effects of Increasing Carbon Dioxide on Vegetation, DOE/ER©0238 (B.R. Strain and J.D. Cure, eds.), U.S. Dept. of Energy, Carbon Dioxide Research Division, Washington, D.C., pp. 155©204.ÄÄ ÃÃKEYWORDS: C3, C4, CO2 ENRICHMENT STUDIES, COMMUNITY LEVEL CO2 RESPONSES, FLOWERING, REVIEW, SPECIES COMPETITIONÄÄ Ã Ã82Ä Ä° `  à ÃBazzaz, F.A., K. Garbutt, and W.E. Williams.Ä Ä 1985. The Effect of Elevated Atmospheric CO2 on Plant CommunitiesÃÃ, TR023 in Yellow Report Series, DOE/EV/04329©5, Dept. of Energy, Carbon Dioxide Research DivisionÄÄ. NTIS, U.S. Dept. of Commerce, Springfield, Virginia. ÃÃKEYWORDS: AIR POLLUTION, C3, C4, CONDUCTANCE, CONTROLLED ENVIRONMENT CHAMBERS, GROWTH, GROWTH ANALYSIS, LEAF PHOTOSYNTHESIS, LIGHT, NUTRITION, PHENOLOGY, REPRODUCTION, REVIEW, SPECIES COMPETITION, SULFUR DIOXIDE, WATER STRESS, WUEÄÄ Ã Ã83Ä Ä° `  à ÃBazzaz, F.A., and K.D.M. McConnaughay.Ä Ä 1992. Plant©plant Interactions in Elevated CO2 Environments. ÃÃAustralian Journal of Botany 40:547©563.ÄÄ Increasing atmospheric carbon dioxide concentrations present a novel resource condition for plant communities. In order 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 consequence, 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 competitors as a result of CO2 enrichment, contrary to expectations based on their photosynthetic pathways. It is now clear that individually 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 is incomplete. We urgently need information about how elevated CO2 atmospheres influence stand formation and population dynamics, specifically with regard to the identities, numbers, sizes and reproductive fitnesses of individuals within single and multiple species stands, if we are to make multi©generational predictions concerning the fate of populations and communities in an elevated CO2 world. ÃÃKEYWORDS: COMMUNITY LEVEL CO2 RESPONSES, ENVIRONMENTAL INTERACTIONS, PLANT©PLANT INTERACTIONS, REVIEW, TEMPERATUREÄÄ Ã Ã84Ä Ä° `  à ÃBeer, S.Ä Ä 1986. The Fixation of Inorganic Carbon in Plant Cells. ÃÃIN: Physiology, Yield, and Economics, Vol. II (H. Enoch and B.A. Kimball, eds.), Carbon Dioxide Enrichment of Greenhouse Crops, CRC Press, Inc., Boca Raton, Florida, pp. 3©11.ÄÄ 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 for 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 mitochondrial 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 plants, this occurs in mesophyll cells. Malate or aspartate is then transported to bundle sheath cells where it is decarboxylated, 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. ÃÃKEYWORDS: C3, C4, CAM, ENZYMES, METABOLITES, PHOTOSYNTHESIS, REVIEWÄÄ Ã Ã85Ä Ä° `  à ÃBeerling, D.J., and W.G. Chaloner.Ä Ä 1993. The Impact of Atmospheric CO2 and Temperature Change on Stomatal Density: Observations from ÃÃQuercus roburÄÄ Lammas Leaves. ÃÃAnnals of Botany 71:231©235.ÄÄ A comparative study of leaves formed on shoots during the spring and summer (lammas) of ÃÃQuercus roburÄÄ from three contrasting geographical locations (Cardiff, Durham and London) gives a measure of the effect of temperature on stomatal density. This is of value in attempting to distinguish the effects of CO2 and temperature on observed stomatal density changes under different CO2 and temperature conditions through the Quaternary. These leaves of normal and lammas shoots will have developed under similar CO2 levels but different environmental temperatures. Our results demonstrate that leaves formed under the warmer summer temperatures had reduced stomatal densities and indices from all sites, compared with their spring counterparts. This trend was also detected from measurements of spring and summer leaves made upon herbarium material collected from the same tree in 1840. The results suggest that for ÃÃQ. roburÄÄ temperature overrides the influence of irradiance intensity and small seasonal (