简介：Plantationsofeucalyptsasshort-rotationtreecropsarerapidlyexpandingintropicalandsub-tropicalregions,includingsouthernChina,wherethesoilsareacidicandavailablephosphorus(P)islimited.Weinvestigatedseedlinggrowth,drymatteraccumulation,andthedynamicsofphotosyntheticrateandchlorophyllcontentofsevenEucalyptusspecies/hybrids(E.dunnii,E.grandis,E.grandis×E.camaldulensis,E.urophylla×E.camaldulensis,E.urophylla×E.tereticornis,E.grandis×E.tereticornis,E.urophylla×E.grandis)inresponsetodifferentlevelsofPsupply(0,6,12and18mg?kg-1KH2PO4).ThephotosyntheticrateandthechlorophyllcontentsignificantlydeclinedasthePsupplydeclinedinalmostalinearfashionforallspeciesasthePstressperiodextended.IntheabsenceofPsupply,heightgrowthofseedlingsofallspecieswassignificantlyimpaired,whilerootcollardiametergrowthandwholeplantdrymatteraccumulationwasnotaffectedbythelevelofPsupplyinmostofthespecies.Significantinter-speciesvariationsingrowth,drymatteraccumulationandphotosyntheticrateinresponsetoPsupplyweredetected.EucalyptusdunniihadthelowestgrowthperformanceacrossalllevelsofPsupplywhileE.urophylla×E.tereticornisshowedsuperiorgrowthperformance.Fromapracticalpointofview,E.urophylla×E.tereticornisissuggestedasacandidatehybridforplantingonslightlyP-deficientsitesinsouthernChinawhileE.dunnii,beingaslow-growingspecies,isnotsuitableforshort-rotationplantation.OnplantationsiteswhereseverePdeficiencyexists,Pfertilizationneedstobeconsideredtoboostrapidgrowthofseedlingssoastomeetthemanagementobjectivesofshort-rotationplantation.

简介：Thenitrogen(N)andphosphorus(P)budgetandtheecologicalefficiencyofapolyculturesystemofseacucumber(Apostichopusjaponicus),jellyfish(Rhopilemaesculenta)andshrimp(Fenneropenaeuschinensis)werestudiedinacofferdam,120.2hainsize.Thenutrientsweresuppliedbyspringtideinflow.Intotal,139600kgNyr-1and9730kgPyr-1inputtothesystem;while118900kgNyr-1and2840kgPyr-1outflowedfromthesystemconcurrently,thustheoutflowwas85.7%(N)and29.2%(P)ofinflow.TheproductionofNandPwas889.5kgyr-1and49.28kgyr-1(seacucumber)and204kgyr-1and18.03kgyr-1(jellyfishandshrimp),respectively.TheutilizationrateofNandPbypolyculturedanimalswas7.8‰and6.9‰,respectively,21.9%and38%higherthanthatofmonoculturedseacucumber.Ourresultsindicatedthatthepolyculturesystemwasanefficientculturesystemofanimalsandaremediationsystemofcoastalenvironmentaswell;itscavenged14.3%and70.8%ofNandP,respectively.Suchanecologicalefficiencymaybeimprovedfurtherbyincreasingeitherthestockingdensityorthesizeofseacucumberorboth.

简介：Aerobicrice(OryzasativaL.)cultivationisconsideredanalternativeproductionsystemtocombatincreasedwaterscarcityandarsenic(As)contaminationinthefoodchain.PotexperimentswereconductedattheWheatResearchCentre,Dinajpur,Bangladeshtoexaminetheroleofwatermanagement(WM),Asandphosphorus(P)onyieldandyieldattributesofboro(varietyBRRIdhan29)andaman(varietyBRRIdhan32)rice.Atotalof18treatmentcombinationsofthethreelevelsofAs(0,20and40mg/kg)andP(0,12.5and25.0mg/kg)andtwoWMstrategies(aerobicandanaerobic)wereinvestigated.YieldattributesweresignificantlyaffectedbyincreasingAslevels.GrainyieldsofBRRIdhan29andBRRIdhan32werereducedfrom63.0to7.7and35.0to16.5g/potwithincreasingAsapplication,respectively,indicatingagreatersensitivityofBRRIdhan29thanBRRIdhan32.Moreover,AstoxicitywasreducedwithaerobiccomparedtoanaerobicWMforallPlevels.Duringearlygrowthstages,phytotoxicsymptomsappearedonBRRIdhan29andBRRIdhan32ricestemswithincreasingAslevelswithoutapplyingPunderanaerobicWM.UnderanaerobicandAs-contaminatedconditions,BRRIdhan29washighlysusceptibletostraighthead,whichdramaticallyreducedgrainyields.Thereweresignificantrelationshipsbetweenthenumberofeffectivetillersperpotandrootdryweight,grainyield,andnumberoffertileandunfertilegrainsperpotforbothBRRIdhan29andBRRIdhan32(P<0.001).OurfindingsindicatethatricecouldbegrownaerobicallyinAs-contaminatedareaswithareducedriskofAstoxicityandyieldloss.