植物生理学 英文课件 Chapter 1 Water metabolism of plants学习资料

植物的营养问题(NutritionofPlants)

土壤营养：Water,Mineralelements

空气营养：Photosynthesis

(光合作用)有收无收在于水!why?1.1

Theimportanceofwaterinplants

1.2

Waterabsorptionbyindividualplantcell1.3

Waterabsorptionbywholeplant1.4

Watertransportationinplantbody1.5Transpiration1.6

PhysiologicalbasesofrationalirrigationChapter1WaterMetabolismofPlants为什么“有收无收在于水”？植物水分代谢的三个过程：吸收水分(cell)植物水分代谢的三个过程：吸收水分(plant)植物水分代谢的三个过程：水分在植物体内运输植物水分代谢的三个过程：水分的排出(lose)怎样合理灌溉(Irrigate)1.1Theimportanceofwaterinplants

1.1.1FunctionsofwaterinplantlifeLifeoriginatedfromsea.Nowater,nolife!MaincomponentoflivingplantcellVacuole(液泡)(90-95%)失水

干旱

代谢紊乱

原生质破坏

死亡Sameplantsunderdifferentenvironments: Shadeandwet?——Sunnyanddry?Differentorgansandtissuesofoneplant:Watercontentofdifferent

kindsofplant:

mango?——rice?Humanbody?Watercontentofplant:80-95%(differentplanttypes) Leaf?——Stem,dormantbud,matureseed?Freewater(自由水)：距离胶粒较远可以自由流动的水分。Statusofwaterinplant(canorcannotmovefreely).Why?Boundwater(束缚水)：靠近胶粒而被胶粒吸附束缚不易自由流动的水分。Cytoplasm(细胞质)ismainlycomposedofproteins,isacolloidal(胶体)system.Proteinshavehydrophobic(疏水)groupsinside,andhydrophilic(亲水)groupsoutside.Hydrophilicgroupsarecohesive(adhesive)towater.Therefore,manywatermoleculesareadsorbed(吸附)onthesurfaceofproteins.Somewaterparticipates

directlyinmetabolism(光合、呼吸、合成、分解等),someisrequiredbyplanttosurviveunderbad(stress)conditions?NodistinctboundaryproteinRatiooffreewater/boundwater:moreimportant

代谢旺盛细胞、组织、器官：高休眠、越冬：低Freewaterparticipatesdirectlyinmetabolism(suchasphotosynthesis,respiration,etc.).Itscontentregulatestherateofmetabolism.自由水含量越大，植物代谢越旺盛。Boundwaterdoesnotparticipatedirectlyinmetabolism,butisrequiredbyplanttosurviveunderbad(stress)conditions.束缚水含量与植物抗性大小有密切关系。Absolutecontentoffreewater/boundSolventforsubstanceabsorptionandtransportation:

不能吸收固态物，物质（矿质、碳水化合物）要溶于水中才能运输。（施肥后淋水）Keepsplantsintheirshape：膨胀

膨压(Turgorpressure)；失水

wilting(萎蔫)。水是极性分子(polarmolecule)hydrogenbond1.1.2Somephysical/chemicalpropertiesofwater

GoodsolventHydrogenbonds,thenthefollowing:O,N…

Highsurfacetension(表面张力)

air-waterinterface; cohesion(内聚力):H2O-H2O adhesion(粘着力):H2O-Solidphase(CW) capillarity(毛细管作用)

Highspecificheat(比热)

bufferplanttemperaturefluctuations

Highlatentheatofvaporization(汽化热)

44kJ/molat25oC,thehighest

coolthemselvesBackCell:structuralandfunctionalunitofplantbodyAbsorption=movementofwateracrossplasmamembraneandvacuolemembrane(tonoplast)1.2Waterabsorptionbyindividualplantcell

concentrationgradient,diffusioncoefficient系数1.2.1.1Diffusion(扩散):shortdistance,individual1.2.1PathwaysofwateracrosscellmembraneThrough

aquaporin水孔蛋白:waterchannelproteinsonplasmamembraneandtonoplast(液泡膜)1.2.1.2Mass(集体)

flowAquaporin+PiAquaporin-P

Ca+dependent蛋白激酶Rate:fasterthandiffusionDirection:noHowtomeasurewaterenergyinasystem(cell)?Movementofwater

needsenergy(水往低处流)1.2.2Osmotic(渗透)absorptionofwater(adrivingforce?)1.2.2.1Waterpotential(水势)Chemicalpotential(化学势,J/mol):totalfreeenergycontainedinagivensubstanceofonemole.Thermodynamics:totalenergyinonesystem

freeenergy(自由能):performingworkboundenergy(束缚能):notperformingworkWaterpotential(水势):ifthegivensubstanceiswater.J/mol植物生理学上的水势概念(waterpotential,ψw):是指水的化学势除以水的偏摩尔体积(volume/molar,18x10-6m3/mol)水势的单位：化学势单位为J/mol(N·m/mol)

偏摩尔体积的单位为m3/mol

两者相除得N/m2

为压力单位Pa(pascal)Theabsolutevalueofwaterpotentialisdifficulttodetermine.Inplantphysiology,thewaterpotentialofpurewaterissettobezero.纯水的水势为零！纯水的自由能最大，水势也最高!?Waterpotentialofsolutions:Negative,Why?Solutionsψw(MPa)PurewaterHoaglandsolutionSeawater1mol.L-1sucrose1mol.L-1

KCl0-0.05-2.50-2.69-4.501.2.2.2ComponentsofΨwofplantcells渗透势(solute/osmoticpotential)

Ψs:由于溶质颗粒的存在，降低了水的自由能。Negative?Positive?Ψs=-iCRT(van’tHoffequation) i： Dissociatingcoefficient C： Molarconcentration R： Gasconstant(8.32J/mol.K) T： Absolutetemperature(K,Kelvin)衬质势(matric

potential)Ψm:

细胞胶体物质亲水性和毛细管对自由水束缚而引起水势降低的值。Negativeorpositive?压力势(pressurepotential)Ψp:

PressurecausedPositive/Negative?Turgorpressure(膨压)inplant细胞中的亲水胶体？Cellulose(纤维素)inCW,proteinsinprotoplast,starches(淀粉)incytoplasm。亲水性:蛋白质>淀粉>纤维素

Legumeseeds吸涨作用(imbibition)重力势(gravitypotential)Ψg:

由于重力的作用Ψw=Ψs+Ψp+Ψm Dry/ImmaturecellsΨw=Ψs+ΨpMaturecells水分移动需要能量，因此，水分一定是从高势区域顺着能量梯度（energygradient）流到低势区域，也就是说，水分由水势高处流到水势低处。Whatwillhappenwhenthereisamembrane(non-permeable,semi-permeable)betweenhighandlowwaterpotentialarea?1.2.2.3Osmosis(渗透作用)半透膜（Semi-permeablemembrane）：让水分子通过而溶质分子不能透过的一种薄膜。种皮、膀胱、皮肤……（烫伤起泡，加盐消之）Plasmamembranesofplantcellsareselectivelypermeablemembranes:waterandsmallunchargedsubstanceslargersolutesandchargedsubstancesStructureofplantplasmamembranefunnelSemipermeablemembrane水分从水势高的系统通过半透膜向水势低的系统移动的现象，就称为渗透作用(Osmosis)。

CW：全透性

Plasmamembrane：选择透性

Protoplastlayer：选择透性

Tonoplast：选择透性1.2.2.4(Mature)plantcellisanosmoticsystemPlasmolysis质壁分离

anddeplasmolysis质壁分离复原tellusthatmatureplantcellisanosmoticsystemHöflerdiagramTherelationshipbetweenwaterpotentialandcellvolume1.2.2.6WatermovementbetweencellsDirection:by

waterpotentialgradient,notbyΨp!Ψs=-1.4MPaΨp=+0.8MPaΨs=-1.2MPaΨp=+0.4MPaABΨs=-1.4MPaΨp=+0.8MPaΨs=-0.8MPaΨp=+0.4MPaCDΨw=-0.6MPaΨw=-0.8MPaΨw=-0.6MPaΨw=-0.4MPaBackWholeplant:rootleafRoothairzoneDon’tdamagethesezonesduringtransplanting!1.3.1Where?1.3Waterabsorptionbywholeplant

1.3.2PathwaysPlasmodesmata

胞间连丝Casparianstrip

凯氏带质外体途径共质体途径跨细胞途径Casparianstrip

凯氏带1.3.3Motivepower1.3.3.1Rootpressure:植物根系的生理活动使液流从根部上升的压力，称为根压。0.05～0.5MPaWaterpotentialgradient:How?Bleeding:从受伤或折断的植物组织溢出液体的现象，叫做伤流。伤流液（bleedingsap）

Guttation吐水LiquiddropletsLeavesoryoungflowerssecretewaterdropletsthroughhydathodes水孔

locatedatthemarginsoftheleavesorflowers.Absorption>transpiration?Mechanismofrootpressure?solutesΨwselectivelypermeableendodermis+activeabsorptionofsolutes1.3.3.2Transpirationpull(蒸腾拉力)Rootpressure可将水压多高?0.05～0.5MPa20.4m

Gianttrees?

Sequoiasempervirens

北美红杉,ThetallesttreeonEarthtoday

is112.5m

Cutflower?Inthesoil:AvailablewaterinthesoilAirconditionsinthesoil:sunnyafterrain?Soiltemperature:ice?Concentrationofsoilsolutions:afterfertilization?Intheair:?1.3.4EnvironmentalfactorsaffectingthewaterabsorptionbyrootsBack1.4Watertransportationinplantbody1.4.1PathwayA:FromsoiltorootB:FromroottoleafC:Fromleaftosubstomatalcavity气孔下腔throughlivingcellsthroughdeadcells:xylem(vessel导管andtracheid管胞)1.4.2RateThroughlivingcells:slowInxylem:fast(3-45m/h)1.4.3PowerofwatertransportationinxylemRootpressure:pushTranspiration:pullContinuous?Howcanwatercolumnsinxylemkeepcontinuous?Transpiration-cohesion-tensiontheory(蒸腾—内聚力—张力学说):H.H.Dixon(Ireland)GravityPull(transpiration)Cohesion20MPaTension0.5~3MPa>BackAproblemofairbubblesinthevesselelement?Cutflower?1.5Transpiration(蒸腾作用)Lossofwaterfromtheplant

guttation:liquid transpiration:gasOnly1-5%waterkeptinplantbodyWhereisthe95-99%?Why?Waste?Transpiration

(蒸腾作用):水分以气体状态，通过植物体的表面(主要是叶子)，从体内散失到体外的现象。Maindrivingforceforwaterabsorptionandtransportation(Howaboutrootpressure?)MaindrivingforcefortheabsorptionandtransportationofmineralsandorganiccompoundsCooldowntheleaves:latentheatofvaporization(sweat)1.5.1PhysiologicalfunctionsoftranspirationYoung: Stem,branches:lenticular(皮孔)transpirationMatureLeaf:cuticular(角质,5-10%)

stomatal(气孔)transpiration(90-95%)1.5.2Siteoftranspiration1.5.3Stomatatranspiration1.5.3.1StomatastructureSmallSmallChloroplast1.5.3.2MechanismsofstomatamovementStomata:sosmall(1-2%ofleafarea),how? Yourlunch:?????????

Perimeterdiffusion（周长扩散）Stomatalmovement:openintheday,closeatnight.Why?starch-sugarconversiontheoryinorganicionuptaketheorymalate(苹果酸)productiontheoryAnincreaseinguardcellturgorpressureopensthestomata;adecreaseclosesit.How?Day:

保卫细胞的叶绿体在光照下进行光合作用，消耗二氧化碳，使细胞内pH增高，淀粉磷酸化酶(starchphosphorylase)便水解淀粉为葡萄糖-1-磷酸，细胞里的水势下降，副卫细胞(或周围表皮细胞)的水分进入保卫细胞，气孔便张开。Night:

呼吸产生的二氧化碳使保卫细胞的pH下降，淀粉磷酸化酶便把葡萄糖-1-磷酸合成为淀粉，细胞液浓度降低，水势升高，水分从保卫细胞排到副卫细胞(或周围表皮细胞)，气孔便关闭。Evidence:differentpHsolutionsStarch-sugarconversiontheoryF.E.Lloyd(1908)Sucroseisanosmoticallyactivesoluteinguardcells保卫细胞的质膜上具有光活化H+泵ATP酶(light-activatedH+-pumpingATPase)Day:

光合磷酸化产生ATP，在分泌H+到细胞壁的同时，把外边的K+吸收到细胞中来，同时伴随Cl-的进入，水势降低，水分进入保卫细胞，气孔张开；Night:?Evidence:将蚕豆叶片表皮放在不同浓度的KCl溶液中;鸭跖草保卫细胞的K+浓度；InorganicionuptaketheoryDay:

当保卫细胞内的部分CO2被利用时，pH上升，剩余的CO2就转变成重碳酸盐(HCO3-)。HCO3-与糖酵解作用产生的PEP，在PEPcase作用下，形成草酰乙酸，进一步还原为苹果酸，水势降低，水分进入保卫细胞，使气孔张开。Night:?Evidence:叶片表皮细胞的苹果酸水平和气孔开度具有密切的正相关。

Malate

(苹果酸)productiontheoryThreetheoriescombined

LightTemperatureConcentrationofCO2WaterWindPlanthormones:Abscisic

Acid(ABA)1.5.3.3Factorsinfluencingstomatamovement1.5.4Insideandoutsidefactorsaffectingtranspiration

扩散力气孔内外蒸汽压差蒸腾速率∝——————∝————————————

扩散途径阻力气孔阻力+气孔外扩散层阻力1.5.4.1OutsidefactorsLight:openstomata,gradientRH:gradientTemperature:gradientWind:gentle,strong1.5.4.2Insidefactors

StomatafrequencyStomataapertureVolumeofsubstomatalcavityTranspirationrate（蒸腾速率）:植物在一定时间内单位叶面面积蒸腾的水量。Transpirationratio（蒸腾比率）:植物每消耗1kg水时所形成的干物质质量（g）。Transpirationcoefficient（蒸腾系数）/Waterrequirement（需水量）:植物制造1g干物质所需水分