太空生存太空生存太空生存 (15).pdf
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1、REGULAR PAPEREffects of different elevated CO2concentrations on chlorophyllcontents,gas exchange,water use efficiency,and PSII activityon C3and C4cereal crops in a closed artificial ecosystemReceived:23 November 2014/Accepted:26 March 2015?Springer Science+Business Media Dordrecht 2015AbstractAlthou
2、gh terrestrial CO2concentrations CO2are not expected to reach 1000 lmol mol-1(or ppm)formany decades,CO2levels in closed systems such as growthchambers and greenhouses can easily exceed this concen-tration.CO2levelsinlifesupportsystems(LSS)inspacecanexceed 10,000 ppm(1%).In order to understand howph
3、otosynthesis in C4plants may respond to elevated CO2,itis necessary to determine if leaves of closed artificialecosystem grown plants have a fully developed C4photo-synthetic apparatus,and whether or not photosynthesis intheseleavesismoreresponsivetoelevatedCO2thanleavesofC3plants.Toaddressthisissue
4、,weevaluatedtheresponseof gas exchange,water use efficiency,and photosyntheticefficiency of PSII by soybean(Glycine max(L.)Merr.,Heihe35)of a typical C3plant and maize(Zea mays L.,Susheng)of C4plant under four CO2concentrations(500,1000,3000,and 5000 ppm),which were grown under con-trolled environme
5、ntal conditions of Lunar Palace 1.Theresults showed that photosynthetic pigment by the C3plantsof soybean was more sensitive to elevated CO2 below3000 ppm than the C4plants of maize.Elevated CO2 to1000 ppminducedahigherinitialphotosyntheticrate,whilesuper-elevated CO2 appeared to negate such initial
6、 growthpromotion for C3plants.The C4plant had the highest ETR,uPSII,and qP under 5003000 ppm CO2,but then de-creased substantially at 5000 ppm CO2 for both species.Therefore,photosyntheticdown-regulationandadecreaseinphotosyntheticelectrontransportoccurredbybothspeciesinresponse to super-elevated CO
7、2 at 3000 and 5000 ppm.Accordingly,plants can be selected for and adapt to the ef-ficient use of elevated CO2concentration in LSS.KeywordsElevated CO2?Gas exchange?Water useefficiency?Chlorophyll fluorescence?C3and C4plants?Life support systemsAbbreviationsANet photosynthetic rateLSSLife support sys
8、temsCarCarotenoid contentChl aChlorophyll aChl bChlorophyll bChl a/bChlorophyll ratioChl totTotal chlorophyll contentCiIntercellular carbon dioxide concentrationETRPhotosynthetic electron transportFv/FmOptimal photochemical efficiency of PSIIFv/FoPotential activity of PSIIGsStomatal conductanceICEIn
9、stantaneous carboxylation efficiencyIWUEIntrinsic water use efficiencyPTNDSPorous-tube nutrient delivery systemqPPhotochemistry quenchingqNNonphotochemistry quenchingTrTranspiration rateWUEWater use efficiencyuPSIIEffective quantum yield of PSIICO2Carbon dioxide concentrationGuest Editor:Congming Lu
10、.&Hong L1School of Biological Science and Medical Engineering,Beihang University,Beijing 100191,China2Institute of Environmental Biology and Life SupportTechnology,Beihang University,Beijing 100191,China3International Joint Research Center of AerospaceBiotechnology&Medical Engineering,Beihang Univer
11、sity,Beijing 100191,China123Photosynth ResDOI 10.1007/s11120-015-0134-9IntroductionAccording to the intergovernmental panel on climatechange(IPCC),the preindustrial levels of carbon in theatmosphere rose from 285 lmol l-1to the current level of384 lmol l-1and the predicted rise in the atmosphericCO2
12、would approach 700 lmol l-1by the year 2050(IPCC2007).Such an abnormal rise in the levels of atmosphericCO2would result in direct and indirect global climatechanges.Although terrestrial CO2concentrations CO2 arenot expected to reach 1000 lmol mol-1(or ppm)for manydecades,CO2levels in closed systems
13、such as growthchambers and greenhouses can easily exceed this concen-tration.CO2levels in life support systems(LSS)in spacecan exceed 10,000 ppm(1%).For several years,plantgrowth has been studying in closed,controlled environ-ments typical of what might been countered in space.Inparticular,we have b
14、een interested in the effects of super-elevated CO2concentrations in these environments.In thespace shuttle cabin atmosphere(*101 kPa total pressure),CO2concentrations typically range between 4000 and6000 lmol mol-1,butconcentrationscanexceed10,000 lmol mol-1with large crews(Wheeler et al.1999).Thus
15、,the CO2levels for advanced life support systemsmay be at super-elevated levels,and CO2may be used as apressurizing gas for growing plants on Moon or Mars(Wheeler et al.2001).Similar situations exist on the Rus-sian Mir space station and will probably occur on theplanned International Space Station(
16、Mitchell et al.1994).If plant research is to be carried out in these settings,and ifplants are ultimately used to provide food,O2,clean water,and CO2removal for long duration missions and biore-generative life support system(BLSS)(Dong et al.2014),the effects of super-elevated CO2on plants will need
17、 to beunderstood.In general,these studies have shown that increases inCO2(e.g.,a doubling from 350 to 700 lmol mol-1)in-crease photosynthetic rates for C3 species and decreasewater use per unit area of vegetation for C3and C4species(Ho gy and Fangmeier 2008;Allen et al.2011).The presentatmospheric C
18、O2 limits growth of C3crop plants,whichshow responses to elevated CO2 via reduced photorespi-ration and enhanced photosynthetic rates,thereby increas-ing their growth and yield.The extensive literature on theimpacts of elevated CO2demonstrates both positive andnegative photosynthetic responses in di
19、fferent groups ofhigher plants,could be attributed to differences in ex-perimental technologies,plant species used for the ex-periments,age of the plant as well as duration of thetreatment(Sage 2002;Davey et al.2006;Reddy et al.2010).During photosynthesis,plants transpire large quan-tities of water
20、to the atmosphere in exchange for CO2acquisition(Kocacinar 2014).Therefore,there should be abalance in plants for this exchange under each specificenvironmentalniche(TyreeandZimmermann2002;Sperry 2003).Though the C3pathway of photosynthesis dominatesmost terrestrial ecosystems,another pathway,C4,is
21、im-portant in certain agricultural and natural systems.The C4pathway is common among species native to tropical andsubtropical grasslands,and important crop species such ascorn,sorghum,sugar cane,and pasture grasses possess C4photosynthesis.In general,these studies have shown thatincreasesinCO2(e.g.
22、,adoublingfrom350to700 lmol mol-1)increase photosynthetic rates for C3species and decrease water use per unit area of vegetationfor C3and C4species(Drake et al.1997).C4differs fromC3photosynthesis in several important biochemical andphysiological properties.In both types,rubisco fixes CO2into the ph
23、otosynthetic carbon reduction pathway commonto all aerobic photosynthetic organisms,but the rubiscoreaction is compartmented differently(Collatz et al.1992).In C3photosynthesis,CO2fixed by rubisco is obtaineddirectly from the intercellular spaces of the leaf by diffu-sion,whereas in C4plants,CO2is d
24、elivered to rubisco,which is located in the bundle sheath chloroplasts,by ametabolic pump that concentrates CO2(Terashima et al.2001).The elevated CO2concentrations maintained in thebundle sheath cells at the cost of additional ATP have thebenefit of inhibiting photorespiration.Consequently,C4plants
25、 lack several features of C3plants that are associatedwith photorespiration(Collatz et al.1992).In addition,thekinetics of the photosynthetic CO2response also differ,because for C4metabolism,the initial CO2fixation is via amore efficient catalyst,PEP carboxylase(Drake et al.1997).These differences i
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