《大量元素钾》PPT课件

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1、第四章植物大量元素（钾）Section1GeneralIngeneral,K20contentinplantsisabout0.3~5%ofdryweight.主要农作物不同部位中钾的含量（%）作物部位含K2O作物部位含K2O小麦籽粒0.61水稻籽粒0.30茎杆0.73茎秆0.90棉花籽粒0.90马铃薯块茎2.28茎杆1.10叶片1.81玉米籽粒0.40糖用甜菜根2.13茎杆1.60块茎5.01谷子籽粒0.20烟草叶片4.10茎秆1.30茎2.80Potassiumischaracterizedbyhighmobilityinplantsatalllevels(cel

2、ls,tissues,long-distancetransport),whichiseasilytransportedfromrootstoshoots.ThereisastableKconcentrationincytoplasm,whichisabout100~200mM,theotherKstoresatthevacuole.干物质含钾量（%）细胞质液泡012345K+浓度(nmol/l)3002001000UnlikeNandP,Kexistsinplantasanion(K+),anddoesnotformstablecomplexes.Nutritionf

3、unctionofK+involves:neutralizingthesolubleandinsolubleanion;StablingpHbetween7and8;Regulatingosmoticpressure;Enzymeactivation;Adaptationtostress---------EnzymeactivationTherearemorethan60enzymeswhicheithercompletelydependonorarestimulatedbyK+.ATPase,pyruvatekinase（果糖激酶）6-phosphofructoki

4、nase（6-磷酸果糖激酶）ProteinSynthesisItisnowwellestablishedthatK+isrequiredforproteinsynthesisinhigherplantsK+isinvolvedinseveralstepsofthetranslationprocess,includingthebindingoftRNAtoribosome.Sotheaccumulationofsolublenitrogencompounds(aa,amide,andnitrate)whenK+isdeficient.PhotosynthesisInhi

5、gherplantsK+affectsphotosynthesisatvariouslevels:※Enhancingchlorophyllsynthesis;※Improvingchloroplaststructure;※IncreasingCO2fixation;※Improvingcarbohydratetransport.OsmoregulationK+isthedominantosmoticsubstances.CellextensionistheconsequenceoftheaccumulationinthecellsofK+.StomatalMovem

6、entInmostspeciesK+hasthemajorresponsibilityforturgorchangesintheguardcellsduringstomatamovement.AnincreaseintheK+concentrationintheguardcellsresultsintheuptakeofwaterfromtheadjacentcellsandacorrespondingincreaseinturgorintheguardcellsandthusthestomataopening.Improvingorganicacidmetaboli

7、smImprovingthetoleranceofplantstostressDrought;Hightemperature;Cold;Disease;Salt;Lodging-----SuitableKcanImprovecropquality:IncreasingproteinandammoniaacidcompositionIncreasingsugarsandstarchcontent;Enhancingvitaminsinvegetables;Delayingstorageperiod;Improvingcommercialquality;