小白菜的贮藏.docx

小白菜的贮藏.docx

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小白菜的贮藏

小白菜的贮藏

更新时间：

2003-9-19 　　来源：

中国蔬菜网

最适储存温度：

0℃

相对湿度：

98%RH以上。

采收后应尽快预冷。

其最佳的储存条件为冰点以上，0℃左右、98～100%RH，约可存放两周。

储存温度高，菜叶易黄化及腐烂，储存寿命较短。

储存温度（℃）051015常温（20℃）

储存期限（天）15-258-106-83-51

大白菜的贮藏

更新时间：

2003-9-19 　　来源：

中国蔬菜网

最适储存温度：

0℃

相对湿度：

98%RH以上

结球白菜最佳的储存条件为0℃，95-100%RH，约可储存1.5-2个月。

采收时受伤的白菜及病叶必须去除，储存环境中不可有乙烯存在。

1%的低氧储存可以延长其储存期限。

储存温度（℃）051015常温（25℃）

储存期限（天）40-7030-5015-3010-204-10

大白菜采后处理

更新时间：

2003-9-12 　　来源：

edis

HandlingFloridaVegetables:

Cabbage1

SteveSargent2

CabbageisgrowninFloridaunderawidevarietyofconditionsbutbestqualityisobtainedduringthecoolerseasonoffall/winter/spring.CabbageproductioninFloridaisintendedforthefreshmarketinthoseareasoftheU.S.unabletoproducecabbageduringthelatefall/winter/spring.Thispublicationisintendedtoassistthevegetable-handlingindustrytoprovidehighqualityfreshcabbagethatisavailable,desirable,andnutritiousfortheconsumingpublic.

PreplantFertilizer

Starterfertilizer.Currentrecommendationsareonlyafractionofthetotalseasonalfertilizerrequirement,eitherliquidordry,beappliedinthebedasastarterfertilizerfordripirrigatedcrops.Thisstarterfertilizerwouldcontainallofthephosphorus（P）andmicronutrientsandupto40%ofthenitrogen（N）andpotassium（K）.OnsoilstestingverylowinPandK,thestartercanbebroadcastorbandedinthebed.IfonlysmallamountsofPandmicronutirentsarerequired,thenitisnormallybettertobandthesematerials.Bandsshouldbeplacedbelowthebedsurface2to4inchesandtothesideoftheplantrow,butnotbetweenthedriptubeandrow.Inmostcroppingsituations,approximately30-40lb/acreofNandKwouldbesufficientinthestarterfertilizermixture.TheamountsofPandmicronutrientsshouldbedeterminedbyacalibratedsoiltest.InsituationswherethesoiltestindexforPishightoveryhigh,thennoPisrequiredinthefertilizer.

Phosphorusandmicronutrients.Ingeneral,PandmicronutrientsarenotrecommendedforsimultaneousapplicationindripirrigationsystemsinFlorida.ThisisbecauseofthepossibilityofprecipitationofPandmicronutrientsorthePandcalciumormagnesiuminthewellwater.ResearchhasshownthatPcanbesuccessfullyappliedthroughdripirrigationsystemswithcertainprecautions（Rolstonetal.,1981;Mikkelsen,1989）.However,ifapplicationofPisrequiredduringtheseason（suchasduringcoldperiods）,itshouldbeinjectedalone.AcidificationoftheirrigationwatertopH4.0to5.0mightbeneededtokeepthePinsolutionduringapplication,especiallywhenusingthehighpHwaterfromtheFloridanaquifer.Acidificationcanbeachievedbyusingphosphoric,sulfuric,hydrochloric,orotheracidstoreducethepHofthewater.Insummary,injectionofPispossibleandcanbeanefficientmethodofPapplication,howeverinjectionmustbedonewithcarefulattentiontowaterpHandisgenerallynotrecommendedforFloridavegetables.

Caution:

Whenacidsmustbedilutedwithwater,alwayspourtheacidintothecontainerofwater.Neverpourwaterintoacidbecauseitwillsplatterwhenitcontactstheacid.

MicronutrientinjectioncanpresentproblemssimilartothoseexperiencedwithPinjection.Thekeyistoavoidprecipitationevents.PotentialproblemswithmicronutrientsarelessseverecomparedtoPbecauseratesofapplicationarenormallymuchlesswithmicronutrientsthanP.Ifmicronutrientsmustbeinjected,thensolubleforms,lesssubjecttoprecipitation,suchaschelates,shouldbeused.LikeP,micronutrientsshouldbeinjectedalonetoavoidpotentialprecipitationproblems.

AlthoughthereareseriousproblemsandconsiderationswithinjectingPandmicronutrients,thereareseveralpotentialbenefitsfromproperinjectionwherewaterchemistryissuitable.Phosphorusandmostmicronutrientsarerelativelyimmobileinthesoilsothatgenerallyonlyoneortwoapplicationsareneededinagrowingseason.Also,inmostFloridavegetablesoils,onlysmallamountsareneeded.Researchhasshownthatplantrecoveryofthesenutrientscanbeincreasedwhentheyareappliedthroughthedripsystem（Rolstonetal.,1981;Mikkelsen,1989）.Thisisprobablyduetoresulting"band-like"applicationinthedrip-irrigatedzonewherethenutrientsarenotwidelymixedwiththesoilwherefixationcanoccur.Althoughonlyaportionoftherootzonewouldbeexposedtothenutrients,researchshowsthatnotalloftherootsystemneedstoabsorbthenutrienttobenefittheplant.

TherehavebeensomeseriouscloggingproblemsinFloridafromimproperlymanagedPandmicronutrientinjections.ThisiswhyinjectingPandmicronutrientsisnotoftenpracticed.Ifinjectionsarerequired,properproceduresshouldbefollowed.

Zeroin-bed（preplantfertilizer）.Insomeproductionsystemswheresoilsarerelativelyhighinorganicmatter,micronutrients,P,andK,itispossibletogrowsuccessfulcropswithnoin-bedfertilizer（i.e.allfertilizer（nitrogen）appliedthroughthedrip-irrigationsystem）.Thisisparticularlyattractiveforareasinthestatewheregrowersexperiencesolublesaltproblemsinthesoils.Reducingtheamountofdryfertilizerappliedinthebedcouldpotentiallyreducesolublesaltinjurytoyoungseedlingsortransplants.TheuseofsolubleNandPstartersolutionswiththetransplantsmightstillbeadvantageousbuttheseamountsofNandPareverysmall.

Slow-release.Forsomecropssuchasstrawberries,tomatoes,andpeppers,benefitcanbeachievedfromusingslow-releasefertilizersinthein-bedstarterfertilizermixturetoprovideanearlyseasonNsupply.Slow-releasefertilizersarelesssubjecttoleachingduringtheearlypartoftheseasonwhenthebedsarewettedwithsubirrigation.Also,slow-releasefertilizershavealowersaltindexsotheyarelesslikelytodamageyoungseedlingsandtransplantsearlyintheseason（Everett,1977）.Supplying30-40lb/acreofNfromslow-releasefertilizer,althoughmoreexpensive,mightbebeneficialforthesecrops.Itisimportanttoselectaslow-releasefertilizerwithanutrient-releasepatternappropriateforsupplyingNtotheyoungcrop.Thispracticeismoreimportantforfallcropswhenfrequentrainreducestheneedforirrigation,yetfertilizerisstillrequiredbytheyoungcrop.

Preplantfertilizer.Sincepreplantfertilizerisappliedinsmallamounts,themostefficientapplicationmethodistobandthefertilizerneartheplantrow.Thefertilizercanbebandedinthebedasdryorliquidmaterialasthebedisformedandpressed.Incorporationoffertilizerbymixingitthroughoutthebedisacceptableifitwillnotbeexposedtoleachingordryingout.

Anyfertilizerplacedinthebedbeforeplantingshouldbeplacedsothatitwillbeleastlikelytoleach,eitherfromraincomingthroughtheholesintheplasticorfromwaterappliedwiththedripirrigationtubing.Thismeansthatfertilizerappliedinbandsshouldbeappliedtotheareaofthebedoutsideofthetubingplacement.Thebandshouldnotbeplacedonthesurfacebetweenthetubingandtherowbecauseirrigationwaterfromthetubingwouldhaveatendencytomovethefertilizersaltstowardtheplantwheresolublesaltinjurycouldoccur.

Fertilizerbandsshouldnotbeplacedonthesurfaceofthebedbecausetheymaydryoutasthesurfaceofthebeddrieswhenthewatertableislowered.Bandedfertilizershouldbeplaced2to4inchesdeepinthebedwhereitwillremainincontactwithmoistsoil,dissolve,andbeavailabletotheplants.In-bedfertilizermaterialscanusemanyfertilizersources.Materialssuchastriple-superphosphate,ammoniumnitrate,potassiumchloride,andpotassiumnitratehaveworkedwellasstarterfertilizers.

Afterpreplantfertilization,theremaining60to80%oftheNandKisappliedinincrementsthroughthecroppingseasonviathedripirrigationsystem.Insomecases,growersapplysomeofthisNandKinbands（"hot-mix"）onthesurfaceofthebed.Thesegrowersfeeltheyneedacertainamountoffertilizerinthebandsforrainyperiodswhentheydonotneedtoirrigatewiththedripirrigationsystem.Inmostsituations,hot-bandsarenotneeded,andmostoftenthefertilizermaterialinthehot-bandsisnotfullyutilizedbythecrop（Figure8）.Thisisbecause,inmanycases,thehot-bandsdryoutafterthewatertableislowered,especiallyintheshoulderarea.AsignificantamountoftheNandKfertilizerinthesehot-bandsisthennotavailabletothecrop.Ifdripirrigationisbeingusedfortheinjectionoffertilizermaterials,itisbesttousethesystemtoitsfullestextent.Thismeansinjecting60to80%oftheNandKthroughthesystem.

（Figure8）.

InjectedFertilizer

Rates.OntypicalFloridasandysoils,inmostsituationsinjectedfertilizerswillconsistonlyofNandK.TheamountofNtouseisdeterminedbythecropnutrientrequirementforNforthatparticularcrop.ThisamountofNisrecommendedforeachcropforeachseason.SpecificrecommendationsforeachcroparepresentedinSP177（HochmuthandHanlon,1995）andinthispublicationfordrip-irrigatedcrops.Recommendationsareundercontinualrevisionasmoreresearchresultsbecomeavailable.

TheKamounttobeinjectedisbasedonthesoiltestpredictedamountofKrequiredforthecropminustheamountthatisappliedinthebedpreplant.Forexample,ifthesoiltestedmediuminK,perhapsonly100lbofK2Ofertilizerwouldberequiredfortheseason.If20%ofthisK2O（i.e.20lb）wereappliedinthebedasstarterfertilizer,then80lbwouldbeinjectedthroughtheseason.

Sources.ThereareseveralsourcesofNandKthatcanbeuse