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Topic: C4 crops

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Research Institute of Crop Production

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	ERS/USDA Briefing Room - Global Climate Change: Questions and Answers
		The size of the stomatal openings is negatively correlated with the atmospheric concentration of CO That is, the higher the level of CO, the smaller the stomatal openings and the slower the rate of transpiration (the loss of water vapor from the plant).
		The yield response of C4 crops (corn, millet, sorghum, and sugar cane) to increases in atmospheric CO is lower (IPCC, 1996).
		A commonly used estimate for the yield response of C4 crops to 555 ppmv of atmospheric CO (double the pre-industrial and 225 ppmv above the 1990 concentration) is 7 percent (Rosenzweig et al., 1993).
	www.ers.usda.gov /briefing/globalclimate/Questions/Cceqa2.htm (591 words)

	Agroforestry parklands in sub-Saharan Africa
		crops which are generally adapted to full light conditions and sown uniformly under and outside parkland tree cover, could not benefit significantly from conditions associated with reduced light intensity.
		crops are adapted to lower light intensities and their yield may be less depressed by partial shade.
		(1992) observed that cereal crop survival was lower in the proximity of trees than in the open and attributed this to higher air and topsoil humidity favouring fungal infection.
	www.fao.org /DOCREP/005/X3940E/X3940E05.htm (5483 words)

	Chapter 6--Agriculture
		Crop yields are sensitive to daily and seasonal levels of solar radiation, maximum and minimum temperatures, precipitation, and carbon dioxide (CO2), and to the soil-drying effects of winds and high temperatures.
		Crops respond to increased concentrations of atmospheric CO2 with greater photosynthetic efficiency, improved water-use efficiency, and greater tolerance for heat, moisture, and salinity stresses (1, 49, 52).
		Crops that exhibit increased insect resistance and herbicide tolerance are expected to be commercially available by the middle to late l990s (103).
	www.ciesin.org /docs/004-071/004-071.html (17200 words)

	Untitled Document
		C4 plants occur rarely in cooler climates in which average temperatures during the growing season are less than about 16°C, presumably because photosynthesis is inhibited by low temperatures (Sage et al., 1999).
		We attempted to separate the C4 and Calvin-Benson cycles in the leaf by chemically inhibiting PEP carboxylase, the enzyme that initially binds CO2 from the atmosphere in C4 plants, and then measuring PEP carboxylase and rubisco activities.
		As crops age, the rate of nitrogen acquisition per unit of ground area declines probably as a result of lowering crop demand for soil nitrogen caused by the internal cycling of nitrogen from aging to young developing tissues and development of more structural tissues.
	www.ferrum.edu /gbyrd/byrdresearch.htm (2012 words)

	Climate Change and World Agriculture
		The canopy of indeterminate crops, however, continues to intercept light until it is reduced by other events such as frost or pests, and the duration of the canopy increases when increased temperatures extend the season over which crops can grow (e.g., by delaying the first frosts of autumn) (Figure 4.2c).
		Whether crops respond to higher temperatures with an increase or decrease in yield depends on whether they are determinate or indeterminate, and whether their yield is currently strongly limited by insufficient warmth.
		The reason for this is that, near the margins of cultivation, the probability of critical levels of warmth or moisture required to avoid crop failure or a critical crop shortfall tends to increase not linearly but quasi-exponentially towards the margin of cultivation (Figure 4.6).
	www.ciesin.org /docs/004-038/004-038a.html (6528 words)

	The Regional Impacts of Climate Change
		Cash crops are important in every country but vary in their distribution and profitability.
		However, the effect of CO on crops in Africa-where nutrients often are a limiting factor and leaf temperatures are high-remains highly uncertain.
		crops are more tolerant, in general, to climate variations involving temperature ranges between 25°C and 35°C. These crops most often are located in warmer, dryer climates; they are quite susceptible to water stress.
	www.grida.no /climate/ipcc/regional/022.htm (1597 words)

	Rising Carbon Dioxide is Great for Plants
		C4 plants also experience a boost in photosynthetic efficiency in response to higher carbon dioxide levels, but because there is little photo-respiration in C4 plants, the improvement is smaller than in C3 plants.
		Since corn and other C4 plants are frequently grown under drought conditions of high temperatures and limited soil moisture, this superior efficiency in water use may improve yields when rainfall is even lower than normal.
		Food crops with C4 metabolism, including corn, sorghum, millet, and sugarcane, show yield increases ranging from 10 to 55 percent, resulting primarily from superior efficiency in water use.
	www.purgit.com /co2ok.html (3536 words)

	Metabolically Modified Rice Exhibits Superior Photosynthesis and and Yield
		Rice, a staple food crop for nearly half of the world's six billion population, is a key target for genetic engineering aiming to develop improved varieties to feed the world's burgeoning population.
		In engineering C4 photosynthesis, there are two important components to be considered: the biochemical pathway (enzymes) and the specialized leaf structure.
		These results were totally unexpected since only one of the maize C4 pathway enzymes is being elevated in the transgenic rice plants and one would not expect this would be sufficient to concentrate CO2 as in a typical C4 plant.
	www.biotech-info.net /metabolically.html (1167 words)

	IRRI - International Rice Research Institute
		The effectiveness of the CO2-concentrating mechanism in a C4 plant is discussed with respect to overcycling by the C4 pathway, the energetics of photorespiration, and CO2 diffusive resistance between Rubisco and phosphoenolpyruvate carboxylase.
		C4 photosynthesis confers substantial benefits upon herbaceous plants in tropical environments, most notably in high-light habitats with frequent drought, heat, and salinity stress.
		However, the potential yield of such a crop in irrigated systems could be limited by the intrinsically low N content characteristic of C4 crops.
	www.irri.org /science/abstracts/007.asp (3828 words)

	Climate Change 2001: Impacts, Adaptation and Vulnerability
		Crop water balances may be affected through changes in precipitation and other climatic elements, increased evapotranspiration, and increased WUE resulting from elevated CO Specific examples of impacts on crops are available.
		Staple crops such as wheat and corn that are associated with subtropical latitudes may suffer a drop in yield as a result of increased temperature, and rice may disappear because of higher temperatures in the tropics (Odingo, 1990).
		Impacts of climatic change on water resources, crop yields, and land resources are used as inputs into the economic model.
	www.pnl.gov /aisu/pubs/eemw/papers/ipccreports/workinggroup2/390.htm (579 words)

	A. Agronomic factors
		For example, in lower Egypt, temperate crops such as berseem clover, wheat, barley and beans are grown in the winter and crops with higher temperature requirements such as cotton, rice and maize are grown during the summer.
		Crops are divided into five adaptability groups on the basis of their photosynthetic carbon assimilation pathways (C3, C4 or CAM) and according to the effects of radiation and temperature on photosynthesis (see Table 33).
		Crops that tolerate drought, yet respond when water is plentiful, can sometimes be grown on such land, or short duration crops can be dropped from the cropping system during the dry period.
	www.fao.org /docrep/X5648E/x5648e0e.htm (12577 words)

	GEO Year Book 2006
		Improvements in crops, techniques of cultivation, and soil and water management may be able to compensate, but increasing food production in these zones will be made that much harder (FAO 2002).
		Shifting growth zones: As a result of rising temperatures, the zones where individual crops do better due to certain climactic conditions are likely to shift polewards and to higher elevations.
		C4 crops are the major food staples of tropical African and Latin American agriculture (IPCC 2001a).
	www.unep.org /geo/yearbook/yb2006/063.asp (1296 words)

	Dr. Steven P. McLaughlin Homepage
		In an additive intercrop both species are planted at the same density as in their respective monoculture; in a replacement intercrop a row of one crop "replaces" a row of the second crop in forming the intercrop.
		Typically, one crop component of the intercrop is more competitive and hence dominates the mixture in terms of growth and yield.
		The absolute yields of crops in the intercrop are lower than their respective yields in monoculture due to competition, but the RYT of the intercrop will be greater than 1.0 if the intercrop captures more limiting resources that the individual monocrops.
	ag.arizona.edu /~spmcl/lecturenotes/diversity.htm (2114 words)

	Yield Potential, Plant Assimilatory Capacity, and Metabolic Efficiencies -- Loomis and Amthor 39 (6): 1584 -- Crop ...
		Because crops are at the mercy of spatial and temporal
		Assumptions are for a maize crop with a closed canopy completely intercepting incident solar radiation and with all leaves functioning at a uniformly small quantum requirement.
		Crop Sci., March 1, 2002; 42(2): 659 - 659.
	crop.scijournals.org /cgi/content/full/39/6/1584 (7272 words)

	Cacti
		Unlike most plants in which photosynthesis takes place only during the day when transpirational water losses can be high, CAM plants open their stomata and take up CO2 during the night when water losses are much lower due to lower ambient temperatures and higher humidity than during the day (Nobel 1988).
		CAM plants are considered slow growers in comparison with C4 crops (e.g., maize), as well as with C3 crops (such as alfalfa, rice and wheat).
		Growers of fodder maintain that they had changed from growing corn and sorghum to growing cactus because corn and sorghum were frequently marginal crops, dependent on a highly variable rainfall whereas they could consistently produce a cactus crop regardless of rainfall variation.
	weather.nmsu.edu /middle-east/cacti.htm (2224 words)

	ScienceWeek
		Modern crop models are widely used in agricultural research and planning and have been shown to be robust and accurate under a wide range of conditions in today's world.
		This is largely because the assumed effects of CO2 on crop growth and water use offset all or part of the negative impacts of warmer temperatures and rainfall changes (3).
		Maize, a C4 photosynthesis pathway crop, should have no direct response to CO2 and should only respond via decreased water requirements (C4 photosynthesis uses a CO2-concentrating mechanism at the cellular level that is less sensitive to atmospheric CO2 than the more common C3 pathway).
	scienceweek.com /2006/sw060714-2.htm (622 words)

	Food-crop yields in future greenhouse-gas conditions lower than expected
		FACE technology, such as the SoyFACE project at Illinois, allows researchers to grow crops in open-air fields, with elevated levels of carbon dioxide simulating the composition of the atmosphere projected for the year 2050.
		Older studies, as reviewed by the Intergovernmental Panel on Climate Change, suggest that increased soil temperature and decreased soil moisture, which would reduce crop yields, likely will be offset in C3 crops by the fertilization effect of rising CO2, primarily because CO2 increases photosynthesis and decreases crop water use.
		Long and four colleagues were co-authors: Elizabeth A. Ainsworth, professor of plant biology; Andrew D.B. Leakey, research fellow in the Institute of Genomic Biology at Illinois; Donald R. Ort, professor of plant biology and crops sciences; and Josef Nösberger, professor at the Swiss Federal Institute of Science and Technology in Zurich.
	www.eurekalert.org /pub_releases/2006-06/uoia-fyi062606.php (662 words)

	Scientists find new way to assess where cotton-killing pests develop
		In a finding that could have broad implications for farmers' ability to stop pests from decimating cotton crops, scientists from North Carolina State University and agricultural research stations in the Cotton Belt have developed a new technique to determine where the larvae of certain agricultural pests develop.
		The research suggests that this non-toxic corn, therefore, provides a major refuge for H. ea moths, and as such is critical to halting the evolution of insecticide-immune pests, perhaps more so than existing small cotton refuges.
		In one October sample, 100 percent of the moths originated from C4 hosts even though C4 crops were harvested at least one month earlier, and no common wild C4 hosts were available.
	www.eurekalert.org /pub_releases/2002-12/ncsu-sfw120302.php (976 words)

	Impact of Global Change on Agriculture (Site not responding. Last check: 2007-10-30)
		Warm temperatures may expand crop producing lands but crops that have become adapted to the growing-season day lengths of the middle and lower latitudes and may not respond well to the much longer days of the high latitude summers.
		Another way would be to breed heat- and drought-resistant crop varieties by utilizing genetic resources that may be better adapted to new climatic and atmospheric conditions.
		In a traditional polder, one crop a year is grown as the lake water recedes.
	www.iitap.iastate.edu /gccourse/issues/agri/agri.html (1293 words)

	Research - Quality of Life - Biotechnology programme (1994-1998)
		The agricultural productivity of temperate crop plants, such as wheat, barley, potatoes and sugar beet, is limited not only by growing conditions, but also by the performance of the photosynthetic apparatus.
		Tropical crops, such as maize, use a different pathway for photosynthesis (C4).
		This project aims to transform C3 crops with recombinant DNA constructs to generate a similar pattern of GDC expression and to see if this improves crop performance and water-use efficiency.
	ec.europa.eu /research/biotech/biotech2-vol3/3-1-17-sub_en.html (279 words)

	Yield and Growth Components of Potato and Wheat under Organic Nitrogen Management -- van Delden 93 (6): 1370 -- ...
		Total N is available N for the crops, estimated as the sum of soil mineral N (0–0.9 m), ENM, and mineral fertilizer N. Crops and treatments are as in Table 2A.
		Means and effects of year (Y), nitrogen (N), and cultivar (C) on average N nutrition index (NNI), crop biomass, grain dry weight, harvest index, light use efficiency (LUE), and cumulative intercepted photosynthetically active radiation (PAR) of wheat at 102 d after emergence (DAE) in 1997 and 86 DAE in 1998.
		crop maturity to be unaffected by N depletion (Millard and Marshall, 1986;
	agron.scijournals.org /cgi/content/full/93/6/1370 (6283 words)

	amaranthushypochondriacus
		Illumination increases the affinity of phosphoenolpyruvate carboxylase to bicarbonate in leaves of a C4 plant, Amaranthus hypochondriacus.
		Modulation by bicarbonate of catalytic and regulatory properties of C4 phosphoenolpyruvate carboxylase from Amaranthus hypochondriacus: Desensitization to malate and glucose 6-phosphate and sensitization to Mg2+.
		Rapid visco-analyzer (RVA) pasting profiles of wheat, corn, waxy corn, tapioca and amaranth starches (A. hypochondriacus and A. cruentus) in the presence of konjac flour, gellan, guar, xanthan and locust bean gums.
	www.newcrops.uq.edu.au /listing/amaranthushypochondriacus.htm (4040 words)

	Shawn Naidu (Site not responding. Last check: 2007-10-30)
		Current research is on the molecular and physiological basis of cold-tolerant C4 photosynthesis in the rhizomatous perennial grass Miscanthus x giganteus, which is closely related to corn and sugarcane.
		As in other C4 crops, this potential in maize is lost at temperatures below 20ºC. The grass Miscanthus x giganteus is from the same taxonomic group as sugar cane, sorghum and maize, and uses the same form of C4 photosynthesis.
		We are using a combination of physiological and molecular techniques to understand the basis of the low-temperature tolerance of C4 photosynthesis in M.
	www.life.uiuc.edu /long/ShawnaNaidu.html (237 words)

	People and Places (Alternate Crops and Systems) (Site not responding. Last check: 2007-10-30)
		Ziska, L. and Bunce, J. The role of temperature in determining the stimulation of CO2 assimilation at elevated carbon dioxide concentration in soybean seedlings.
		Wilson, K. and Bunce, J. Effects of carbon dioxide concentration on the interactive effects of temperature and water vapour on stomatal conductance in soybean.
		Ziska, L. and Bunce, J. Influence of increasing carbon dioxide concentration on the photosynthetic and growth stimalation of selected C4 crops and weeds.
	www.arsusda.gov /acsl/pandp/resumes_pubs/resumebunce.html (1948 words)

	Photosynthesis, Productivity, and Yield of Maize Are Not Affected by Open-Air Elevation of CO2 Concentration in the ... (Site not responding. Last check: 2007-10-30)
		crops in the face of increasing temperatures and water stress.
		Crop Moisture Index (PCMI) is a dynamic, meteorological estimate
		Treatment of major food crops with elevated carbon dioxide and ozone under large-scale fully open-air conditions suggests models may seriously over-estimate future yields.
	www.plantphysiol.org /cgi/content/full/140/2/779 (7336 words)

	Net Carbon Dioxide and Water Fluxes of Global Terrestrial Ecosystems, 1969-1998
		The variability of net surface carbon assimilation (Asmax), net ecosystem surface respiration (Rsmax), and net surface evapotranspiration (Etsmax) among and within vegetation types was examined on the basis of a review of studies performed in either a micrometeorological setting or an enclosure setting.
		The majority of studies involved forests and C3 crops, particularly in the northern hemisphere; however, studies on tropical forests, C4 grasslands or wetlands were included.
		Data are presented for 133 published studies, although individual studies may not have measure all variables of interest.
	www.daac.ornl.gov /FLUXNET/guides/CO2_buchmann.html (553 words)

	What Does It Take to Be C4? Lessons from the Evolution of C4 Photosynthesis -- Edwards et al. 125 (1): 46 -- PLANT ...
		Lessons from the Evolution of C4 Photosynthesis -- Edwards et al.
		In the meantime, notions that crop yields can be improved through greater photosynthetic capacity and that C
		crops and to see them accepted by consumers.
	www.plantphysiol.org /cgi/content/full/125/1/46 (1952 words)

	Future crop yields lower-than-expected under higher carbon dioxide levels
		Open-air field trials involving five major food crops grown under carbon-dioxide levels projected for the future are yielding signifcantly less than those raised in earlier enclosed test conditions.
		In a paper published in the June 30 issue of the journal Science, researchers say that their open-field experiments "indicate a much smaller CO2 fertilization effect on yield than currently assumed for C3 crops, such as rice, wheat and soybeans, and possibly little or no stimulation for C4 crops that include maize and sorghum."
		The scientists also present projections for maize, rice, sorghum, soybean and wheat — the world's most important crops in terms of global grain production.
	news.mongabay.com /2006/0629-crops.html (767 words)

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