u n i ve r s i t y o f co pe n h ag e n

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Pinus merkusii Jungh. & De Vriese

Pousujja, Reungchai; Granhof, Jens; Willan, R.L.

Published in:Seedleaflets

Publication date:1986

Document versionEarly version, also known as pre-print

Citation for published version (APA):Pousujja, R., Granhof, J., & Willan, R. L. (1986). Pinus merkusii Jungh. & De Vriese. Seedleaflets, (7).

Download date: 18. Jan. 2020

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DECEMBER 1986

Pinus merkusii Jungh & De Vriese(Including Pinus merkusiana Cooling and Gaussen)

by

Reungchai Pousujja Ph.D. (N.C.)Jens Granhof andR.L. Willan

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ii

Titel

Pinus merkusii Jungh. & De Vriese (Including Pinus merkusiana Cooling and Gaussen)

Author

Reungchai Pousujja, Royal Forest Department, Bangkok

Jens Granhof, Consultant, Danida Forest Seed Centre

R.L. Willan, consultant, Danida Forest Seed Centre

Publisher

Danida Forest Seed Centre

Series - title and no.

Seedleaflet no. 7

ISSN:

0902-3224

DTP

Melita Jørgensen

Citation

Reungchai Pousujja, Granhof, J, Willan, R.L. 1986, Pinus merkusii Jungh. & De Vriese. Seedleaflet no. 7, Danida

Forest Seed Centre, Humlebæk.

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Electronic Version

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iii

CONTENTS

l. INTRODUCTION 1

Sources of Information 1

2. NOMENCLATURE 1

3. THE TREE 2

Size and Growth Habit 2 Natural Distribution 2 Variation and Improvement 3Importance for Plantation and Uses 5

4. REPRODUCTIVE BIOLOGY 5

Flowering and Fruit/Seed Development 5 Cone and Seed Characteristics 6 Seed Dispersal and Germination 9 Seed and Cone Pests and Diseases 9

5. SEED AND FRUIT PRODUCTION AND COLLECTION 10

Choice and Management of Trees and Stands 10 Cone yield 10 Crop Estimation 11 Maturity Indices 11 Collection Methods 12 Cone Storage in the Forest 13

6. SEED PROCESSING 13

Precuring 13 Cone Drying and Seed Extraction 13 Dewinging 16 Cleaning 16 Seed Yield 17

7. SEED STORAGE AND TREATMENT 17

8. SEED TESTING 19

Sampling 19 Purity and Pure Seed Weight 19 Germination Tests 20 Rapid Tests of Viability 21

9. REGENERATION PRACTICES 22

Nursery Propagation 22 Direct Sowing 22 Natural Regeneration 23

10. References 24

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1

l. INTRODUCTION

Sources of Information

Acomprehensiveaccountof PinusmerkusiiwascompiledbyE.N.G.CoolingandpublishedbytheCom-monwealthForestryInstitute(nowOxfordForestryInstitute)in1968asnumber4intheseriesof FastGrowingTimberTreesof theLowlandTropics.Thepresentnotemakesconsiderableuseof thatpublication.Avaluablesummaryof experienceinThailandiscontainedinWisopakanandGranhof (1983),andinternationalexperienceofP.merkusiiintroductionsandprovenancetrialshasbeenreportedinanumberof paperssubmittedtotheseriesof workshopsandconferencesorganizedbyIUFRO’sworkinggroupsonTropicalProvenanceResearchandBreedingTropicalSpecies.Farandawaythegreat-estexperienceofP.merkusiiliesinIndonesia.Problemsof languagehavepreventedthepresentnotefromdrawingfullyonIndonesianliterature,buttheSeedCentrewillbegladtoproducearevisedversionof thisleafletif andwhensubstancialnewinfor-mationbecomesavailable.

2. NOMENCLATURE

Botanicalname:Pinus merkusiiJunghetdeVriese(includingP. merkusiana CoolingetGaussen)Synonyms: P. sumatranaJungh. P. finlaysonianaWallich P. latteriMason P. merkianaGordonFamily: Pinaceae.

Commonnames:SonSongBai,Merkuspine,Mindoropine,Tenasserimpine.

Note:Until1970thecontinental,SumatranandPhilippineracesof “Pinus merkusii”wereconsideredasconstitut-ingasinglespecies.CoolingandGaussen(1970)describedthedifferencesbetweenthecontinentalandSumatranracesandconsideredthemsowellmarkedastoconstitutetwoseparatespecies.TheyproposedanewnamePinus merkusianaforthecontinentalraces,whileretainingP.merkusiifortheracesindigenoustoSumatraandwidelyplantedinJava;theydidnotdeterminethetaxonomicstatusof thePhilippineraces.

ThepresentleafletcoversboththeSumatranP.merkusii Jungh.etdeVrieseandthecontinentalP. merku-sianaCoolingetGaussen,aswellasthePhilippineraces.

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3. THE TREE

Size and Growth Habit

P. merkusiiisatypicalpinewithfasciclesof 2needles.Itisoftenimpressiveinsizeandstraightnessof boleincomparisonwithassociatedhardwoodsandinrelationtothepoorsiteconditionsunderwhichitisfrequentlyfound.Maturestandscommonlyreachaheightof 30manddiametersof 60-80cm.Excep-tionaltreesmayreach45minheightand140cmindiameter(Cooling1968).

Youngtreesusuallyhaveapyramidalorconicalcrownform,withwell-developedapicaldominance.Latertheyattainaflatterandmorespreadingcrown.

Seedlingsof Sumatranprovenancesstarttomakenormalheightgrowthfromanearlyage,whilethoseof continentalprovenanceshaveamoreorlessprolonged“grass-stage”,duringwhichheightgrowthisinsig-nificantwhilediametergrowthandrootdevelopmentisconsiderable.The“grass-stage”isthoughttohaveabeneficialeffectansurvivalinareaswithaseverefirehazard.

Habitof growthatalateragealsovaries.Thecontinentalprovenancesarestrictlyuninodal,whiletheSumatranprovenancesproduceseveralbranchwhorlsduringayear;anaverageof about3whorlsayearwasfoundinonesamplecountinaSumatranplantation(Cooling1968).TheSumatranprovenancestendtobesinuousinformduringyouth,becomingstraightlater;continentalprovenancesusuallygrowstraightfromthestart,butaremoreheavilybranched.

Occasional“foxtail”treesareseeninpolestagegrowthandinsuchcasesseveralyearsmaypasswithoutthedevelopmentof awhorlof normalbranches.Itissuggestedthatfoxtailingisstronglycorrelatedwith-physicalandchemicalsoilproperties;themorefertilesoilsusuallyhaveahigherincidenceof foxtailing(HamzahandNatawiria1974).

Annualincrementsrecordedfromdominanttreesinthenaturalforestare1to2minheightand0.7to1.0cmindiameter,oncethegrassstageispassed(Cooling1968).

Thebarkisusuallyverythick,deeplyfissuredinapredominantlyverticaldirectionandashen-greyincol-ouronthesurfacebutreddish-brownbeneath.Onmaturetreesbarkthicknessiscommonly4-6cm.TheTapanuliprovenanceinSumatraisanexception,beingsmooth,thin(0.5-2cm)andpalegreyincolour(Cooling1968).

Natural Distribution

P. merkusiiisoneof thefewtrulytropicalpinesintheworld,occurringnaturallyinSoutheastAsiancoun-tries:Burma,Thailand,Laos,Kampuchea,Vietnam,Indonesia(Sumatra)andthePhilippineIslandsof LuzonandMindora.Itisuniqueinthatitsnaturaldistributionjustcrossestheequatorintothesouthernhemisphere.Latitudinalrangeisapproximately230Nto20S(WinaiSirikul1980).ItoccursalsoinChina,intheislandof Hainan,butisthoughttohavebeenintroducedthere(CritchfieldandLittIe1966).

Ithasalargealtitudinalrangefrom30mabovesealeveltoover1,800m.Itisfoundonadiversityof soils

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overmanydifferentparentmaterialsandunderclimatesthatvaryfrommarkedlyseasonal(nearlysixdrymonths)indrymonsoonclimatestoconstantlyhumidequatorialconditionswithlittleornomoisturedeficit(Cooling1968).Meanannualrainfallvariesfrom3,800mminZambalesinthePhilippinestoonly1,000-1,200mminpartsof continentalAsia.Inmostof theSumatranpineareasnomonthreceiveslessthan50mmrainfall,whileinthedriercontinentaloccurrences6consecutivemonthsreceiveless(Cooling1968).Meanannualtemperaturevariesfrom19°Cto28°C(Webb et al. 1980).

Thetypeof forestinwhichP.merkusiioccursvariesconsiderably.OnsandstoneplateauxincontinentalAsiathespeciesmayoccurasalmostpurepinewoodlandovergrass.Inothercasesitisassociatedwithdrydipterocarporotherhardwoodforest.Itspersistenceagainstthecompetitionof thehardwoodsisoftendependentonregularburning,butmayalsobeassociatedwithlocallypooreranddriersitessuchasspursandridgetops.Itisacommoncoloniseronnewlyexposedmineralsoilsuchaslandslipswhichoc-curinSumatra(Cooling1968).

Themoststrikingcharacteristicaboutthedistributionwhenmapped,isitsdiscontinuity(CritchfieldandLittle1966,WinaiSirikul1980).ThebiggestareasofP.merkusiiforestarethoseinN.W.Thailand/S.E.BurmaandtheAtjehprovenanceinnorthernSumatra.Thenumerousotheroccurrencesaremuchsmallerandwidelyseparated.Thediscontinuitysuggeststhelikelihoodof geneticvariation,notonlybetweenthecontinentalandtheinsularprovenances,butalsowithinthem.

Variation and Improvement

Probablyasaconsequenceof itswideanddisjunctgeographicdistribution,thisspeciesvariesconsider-ablyingrowthandothercharacteristics.Thereisstrongevidenceof twoseparatetaxa,namelySumatranandcontinentalgroupsof provenances.Themarkeddifferencesbetweenthesetwotaxahavebeenpre-sentedinrespectof seedweight,presenceorabsenceof grass-stageintheseedlings,nodalhabit,needleandconedimensions,wooddensitypatterns,oleoresinconstituents,treesizeandboleform,andnaturalhabitat(Cooling1968).

Withineachof thetwomainprovenancegroups,thereisfurtherevidenceof variation.Thisemphasisestheneedforcarefulattentiontosourceidentificationof allseeds.Thesourcesshouldbetreatedquiteseparatelyinspeciesandprovenancetrialsorotherexperiments.

Thecontinentalprovenancesarewelladaptedtowithstandfireinaseasonalclimatewithamarkeddryseason(3-6months).Thethickbarkandstoutcrowdedneedlesinthegrass-stageprovideprotectionagainstfire,butintheabsenceof firethistypeisliabletosuppressionbycompetinghardwoods.Incon-trast,theseedlingsof Sumatranprovenancesarelikelytosucceedbestinnear-equatorialconditionswithhighrainfallandhumidityandashortornodryseason.Theyareslender,makerapidheightgrowthcon-tinuouslythroughmostof theyearandarebetterabletocompetewithhardwoodsbyvirtueof theirfastgrowth.Thereisalsovariationwithinthecontinentalprovenances.Asreportedbelow,samelowlandprov-enancesfromeasternThailandhaveamuchlesspronouncedgrassstagethantheprovenancesfromN.W.Thailand.LikewiseinVietnamadistinctionisrecognizedbetweeninitiallyslowergrowingprovenances(QuangNingandLamDangprovenances)andinitiallyfastergrowingprovenances(ThangHoaandHueprovenances)(Granhof 1984).

Inter-provenancegeneticdifferenceshavebeenconfirmedbyseveraltrials.WinaiSirikul(1980)foundthat,after10months,100%of seedlingsoriginatingfromaWestJavaplantation(presumedAtjehprov-

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enance)andfromanaturalPhilippine(Mindora)provenancehademergedfrom(orneverhad)agrassstage.Thecorrespondingfigureforlowaltitudecontinentalprovenanceswas48%andforhighaltitudecontinentalprovenances7%.Acomprehensivetrialof 8Thaiand6non-Thaiprovenancescon-ductedinThailandshowedthatearlyheightgrowthof aBulolo(PapuaNewGuinea)landraceof Atjeh(Sumatra)originwasgreatlysuperiortoallotherprovenances.However,byage9twolowaltitudeprovenancesfromeasternThailand(SangkhaandHueyTa)hadovertakenthePapuaNewGuinea/Atjehprovenance.TwoprovenancesfromMindora(Philippines)werenext,followedbyaZambianlandraceof Vietnameseorigin.HighaltitudeThailandprovenances,withoneprovenancefromnearsealevelinS.W.Thailand,andtwoZambales(Philippines)provenancesgavetheslowestheightgrowth(HubertzandWinaiSirikul1983).ThetwoeasternThailandprovenancesalsoexhibitedthebeststemform,fol-lowedbyoneof theMindora(Philippines)provenances.TheAtjehprovenancewasoneof thepooreronesinstemform,withmuchdiebackandforking,duetostembarers,andfrequentbends.

SomewhatsimilarresultswereobtainedintrialsatBuhindiinTanzania(Madoffe et al. 1984).At10yearsaplantationlandracefromPekalongan(Java)of presumedAtjehoriginhadgrownfastest(meanheight14.6m,meanDBH19.8cm),butwasthepoorestinstemform;italsoproducedthegreatestnumberof cones.AneasternThailand(Surin)provenancewasthesecondfastestgrowing,substantiallysuperiortouplandThaiprovenances;itsformwassuperiortotheIndonesianprovenancesbutinferiortotheslower-growingThaiprovenances.

SomewhatdifferentresultswereobtainedinZambia(Mubita1984).Atnineyearsalocallandraceof Bur-meseorigin,whichnolongerexhibitsagrassstageunderZambianconditions,hadmadethefastestheightgrowth(9.2min9years),followedbytwolowaltitudeeasternThailandprovenances.AJavaplantationprovenancewasrankedfourthforheightgrowthbutfirstfordiametergrowthand,surprisingly,firstforstemform.SincetheseedhadcomefromadifferentlocalitythanthatusedintheTanzaniantrial,itispossiblethattheoriginof theJavaplantationwasTapanuli,whichisreputedtobeslowerbutconsiderablestraighterthantheAtjehprovenance.OnceagainthelowaltitudeeasternThailandprovenancesdemon-stratedtheircapacityforgoodgrowth.

Considerablescopealsoexistsforselectionandbreedingwithinprovenances.Between1963and1968Zambiaplanted26.9haof seedorchards,coveringfourdifferentorigins(Mubita1984).Thailandhastwoseedlingseedorchardswhichincludethreedifferentseedsources(Granhof 1983),whilePapuaNewGuineahasasmallclonalseedorchardplantedbetween1967and1976(Howcroft1978).Thebiggestareaof seedorchardsisinIndonesia,wheretheDirectorateGeneralof ReforestationandLandRehabilitationisreportedtohaveestablished36haof clonaland288haof seedlingseedorchardsby1985(HendiSu-haendi1985).AnadditionalfiveclonalseedorchardsareownedbytheForestResearchandDevelopmentCentre,Bogor.

Inter-racialhybridizationbycontrolledpollinationandreciprocalcrossesbetweenSumatranandmainlandprovenanceshavebeentriedoverseveralyearsthroughco-operationbetweentheThai-DanishPineIm-provementCenterandtheDepartmentof ForestsinPapuaNewGuinea.Thesecrossingsinvolvednorth-ernThaiparentsof continentalprovenanceandparentsinPapuaNewGuineaof theSumatran(Atjeh)provenance.HybridsgrowninThailandexpressedcharactersintermediatebetweenthetwoparentprov-enancesand,mostimportant,showedalmostcompleteabseoce(lessthan10%)of thegrassstageafter10monthsinthenursery(Granhof 1983).HybridsalsoshowedpromiseinPapuaNewGuinea(Howcroft1978).

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Importance for Plantation and Uses

Largeareasof plantationshavebeenestablishedinonlyonecountry,Indonesia,wherewellover100,000haof theSumatranprovenanceshavebeenestablished,mainlyinJava.Thegreatestpartisof Atjehprov-enance.Elsewheretheslowstart,duetograssstage,of manycontinentalprovenancesandthepoorformof theinsularprovenanceshavecausedforesterstopreferPinuscaribaeaforthetropicallowlandsandP.oocarpaforthemiddlealtitudes.Zambiahas860haof plantation.Manyothercountrieshavetrialsorsmallpilotplantations.

P. merkusiiproducesageneral-purposesoftwoodtimber,usefulforconstructionandjoinery.Thesapwoodiswhiteorpaleyellow,heartwoodreddishbrown.Wooddensityvariesbetween0.44and0.59g/cc(Webb et al. 1980).Informationonpulpingpropertiesissparse;onetestof 511-yearoldtreesgrowninMalay-siasuggestedthatthepulpwassomewhatweakerthanthatof comparableP.caribaeagrowninthesamecountry(PehandPalmer1969).Thespeciesisahighresin-yielderandcommercialtappinghasbeenprac-tisedinseveralcountries(Cooling1968).Lasschuit(1978)reportedthatoldtreescouldyield30-60kgof crudegumpertree,producing20-40kgof pureresinand7-14kgof turpentine,eachyearwhentappedtoexhaustion.

4. REPRODUCTIVE BIOLOGY

Flowering and Fruit/Seed Development

P. merkusiiismonoecious.Maleflowersareborneinclustersorspikes,mainlyinthelowerpartof thecrown,6-10cmfromthetipsof thebranchlets.Bothmaleandfemalestrobilimayoccuronthesameshoot,themaleflowersbeingafewcentimetersbelowthefemale.ObservationsinN.W.Thailandshowedthatflowerbudsbecomevisiblearoundthemiddleof January.Malecatkinsare2-4cmlong,withanaver-ageof 2.5cm,by0.5cmwideandcarrytwobilocularmicrosporangiabearingnumerouspollengrains,whicharerenderedbuoyantintheairbyhavingtwolateralairsacs.Thepollengrainsareslightlysmallerthanthoseof P.kesiya.Theperiodbetweentheappearanceof maleflowerbudsandpollenshedisaboutsixweeks,i.e.inThailandfromthemiddleof FebruarytoearlyMarch,thepeakbeingattheendof Feb-ruary.Theindividualtreeflowersshedpollenforapproximately2weeks(Kingmuangkow1983).InIndo-nesia,pollenshedhasbeenobservedatalltimesof theyear,butthemainperiodwasMarch-June(Buys et al. 1928,quotedinCooling1968)SumatranprovenancesplantedinPapuaNewGuineaalsoproduceflow-ersthroughouttheyear(Howcroft1974).Femalestrobiliaremostfrequentintheupperthirdof thecrowntowardstheendsof exposedlateralsandontheleaderitself.InThailandthebudsappearinlateJanuary,andtheovuliferousscalesopenbe-tweenthemiddleof FebruaryandearlyMarch.Thereceptiveperiodjudgedbyappearanceis5-7days.Theperiodof floweringdoesnotprovideprotectionagainstself-pollination,receptivefemalestrobilibe-ingpresentattheperiodwhenmalestrobilionthesametreearesheddingpollen(Kingmuangkow1983).Althoughfemaleflowersmayappearatanytimeof theyearintheSumatranprovenances,theirrateof developmentiscomparablewiththeThaiobservations.Howcroft(1974)inPapuaNewGuineafoundthattheperiodfromthefirstappearanceof theflowerbudtotheendof thereceptiveperiodvariedfrom27to39daysaccordingtoclone.

Inthecontinentalprovenances,femalestrobiliareborneinones,twosatthreeshighinthecrown,butin

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theSumatranprovenancestheymaybeborneindenseclustersof twentyormore,althoughtwotosevenismoreusual.RipeconesarefoundmuchfurtherbackfromthebranchtipsinSumatranthanincontinentalprovenances(Cooling1968).

InN.W.Thailanditwasfoundthatconesdevelopfrompollinationtomaturityinabout12½months.Duringthefirst4monthstheconeletswere0.7-2cmlang.Duringthefollowing4-monthperiodthecone-letsgrewrapidly,increasinginlengthbyapproximately20mmmonthly.Bytheendof November,theyreachedfullsize(10-12cm).Intheperiodof DecembertoMarch,theconesgraduallychangedcolourfromgreentobrownandbecamefullymaturedandreadyforcolleetionattheendof Marchorthebegin-ningof April(Kingmuangkow1983).

Periodof conematurationvariesconsiderablyaccordingtoprovenance.IneasternThailandtheperiodfrompollinationtoseedmaturityislongerthaninN.W.Thailand,i.e.14-15months(Granhof 1975).Inagraftedclonebankof AtjehprovenancegrowinginPapuaNewGuinea,Howcroft(1974)foundthattheperiodfrompollinationtoconematurityaveragedon1yabout9½months,withextremesbetweenrametsandyearsof 241and318days.InIndonesiaHarahapandMukti(1976),workinganlocalprovenances,foundthattheaverageintervalbetweenpollinationandconeripeningwas336days.Thereisconsiderablevariationbetweentreesaswellasbetweenprovenances.

Cone and Seed Characteristics

Thematureconesof Sumatranprovenancesareusuallycylindrical,taperingtoabluntpoint,whiletheconesof continentalprovenancesusuallytapermorestrongly;theirwidestpointbefaretheyopenisataboutanethirdof theirlength.Openconesof bothmainprovenancesaremoreorlessovoid-conicinshape.

Conelengthvariesfromprovenancetoprovenance.Continentalprovenancesappeartoaveragesome-whatlargerthanSumatran.Kingmuangkow(1983)reportedanaverageof 9-11cmforN.W.ThailandandNguyenKha(1965)8-13cminVietnam,whileHowcroft(1974)reportedanaverageof 7-9cmforAtjehprovenanceinPapuaNewGuineaandCooling(1968)5-8cmforAtjehand6-10cmforTapanuli.InthePhilippinesconesare4-9cmlang(Turnbull1972).Matureconesare2-4cmwidebeforetheyopenandmaybeupto10cmafteropening.

Thescalesarewoodywithaprominentapophysisandacentrallozenge-shaped,slightlyglossyumbowithamoreorlesspersistentandslightlyreflexedpoint.

Inonestudythenumberof conescalesperconeinasamplecollectedinThailandvariedfromconetocone,rangingfrom121to132conescales.Thisimpliesapotentialmaximumseedproductionof about250percone,sinceeachconescalemaycarryuptotwoovules.Butinfacttheaveragenumberof devel-opedseedsperconewas72orabout29%of thepotentialcapacity.Thehighestnumberof developedseedswaslocatedinthemiddlepartof thecone.ASumatranprovenancewasfoundtohavesmallerconesize,withanaverageof 88conescales(Bhu-mibhamon et al. 1980).Turnbull(1972)reportedthattheaverageconeweightof matureconesintheMindoroprovenanceof Philippineswas10.4gpercone(range4.7~12.5g),substantiallysmallerthantheZambalesprovenanceof average14.0g(range10.2-19.6g).StillbiggerdifferencesbetweentheSumatranandthecontinentalprovenanceswererecordedbyCooling(1968).Sumatranprovenances

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PInus merkusii Jungh & de Vriese

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PInus merkusii Jungh & de Vriese

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variedfrom3.2to11.7gandcontinentalfrom14.0to48.7g;coneswerefullyopeninthiscaseandwereweighedafterninemonths’airdrystorageunderlaboratoryconditions,sofreshweightof unopenedma-tureconeswouldhavebeensignificantlygreater.

Twowingedseedsareborneatthebaseof eachwell-developedconescale.Thewingsareunequal-sidedandvaryfrom22to30mminlengthby5-8mminwidth.Theyareattachedtotheseedbybasalhooksconnectedtohygro-scopictissueinthebaseof thewings,withtheresultthattheseedisfirmlyheldwhileinadrycondition,favouringwinddispersal,butisquicklyreleasedwhenmoistconditionssuitableforger-minationareencountered.

Seedsareusuallymottledfawnandblackbutsomeareuniformincolour,othersareapalereddish-brown.Seedsizevariesfrom7to8mminlengthand4to5mminwidth.Seedsareflattenedincrosssection,2-2.5mmthick.

Conesareshedsoonafterreleasingthelastof t.heripeseedandarenotpersistentonthetreeasisthecasewithP.kesiya.onlyoccasionallydoesoneseeemptyconesof thepreviouscropamongthecurrentripeones(Cooling1968).

Seed Dispersal and Germination

Seedisdislodgedanddispersedfromtheopenconebywind.Seeddispersalof mostcontinentalprov-enancesisfromMarchtoJune.Sumatranprovenancesmayshedseedatanytimeof theyearbutthepe-riodof maximumseedfallinnaturalstandswasreportedbyBuys et al. (1928,quotedinCooling1968)tobeJuly-November.InplantationsgrowinginW.Java,S.SumatraandS.Kalimantan,MartiniandSemadi(1980)foundthatMaytoJulywasthebesttimetoharvestripecones.InthePhilippines,matureconesmaybefoundfromJanuarytoAugust,withapeakinMarch/April(Turnbull1972).

Germinationisepigeal.Infavourableconditions,asinanursery,germinationisrapid,startingafter8days.Cotyledonsmayvaryfrom5to12,mostcommonly7or8,andareabout3cmlongxlmmwide(NguyenKha1965,BurleyandCooling1972).Cotyledonsarefollowedbyprimaryorjuvenileneedlesandlaterbysecondaryoradultneedles,butdevelopmentvariesgreatlyaccordingtowhetheragrassstageisformedornot.

Seed and Cone Pests and Diseases

InThailandtwospeciesof moth,Dioryctria abietellaandD. sylvestrella,cancausesevereconelossesbylay-ingeggsonyoungcones;thelarvaeburrowintothetissuesanddestroyconesandseeds(Chaiklom1975).SimilardamagebyDioryctrialarvaehasbeenreportedfromthePhilippines(Gordon et al. 1972).Sownseed,aswellasnewlygerminatedseedlings,maybeattackedbyavarietyof insectsincludingcrickets,molecrickets,grasshoppers,cut-wormsandants(Cooling1968).

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5. SEED AND FRUIT PRODUCTION AND COLLECTION

Choice and Management of Trees and Stands.

Whereverpossible,seedshouldbecollectedfromstandswhicharebetterthanaverageinbothformandvigour.Naturalstandsshouldbeof sufficientagetoproducesubstantialcropsof seeds.NguyenKha(1965)reportsP.merkusiiasbearingheavycropsat20yearsof ageinnaturalforestinVietnam.Hereportedisolatedtrees,withamplespaceforcrowndevelopment,asproducingcropsbyaboutage10.However,seedshouldnotbecollectedfromisolatedtreesbecauseof theriskof selfing.Sumatranprov-enances,whichhavenograssstage,maybeexpectedtoproduceseedearlierthancontinentalprovenancesandmanagedplantationsearlierthannaturalstands.InaprovenancetrialinTanzaniaitwasfoundthatafter10years85%of thetreesof fourThaiprovenanceshadnocones,whereasinthePekalonganJava(exAtjehSumatra)provenance86%hadoneormoreconesand4%bore250conesormore(Madoffe et al. 1984)Inallcasesitisadvisabletodefercollectionuntilatleastage10inorderthatthestandcande-velopcharacteristicswhicharelikelytobemaintainedfortheremainderof therotation.

Withinanunimprovedstand,itisdesirabletorestrictcollectionto“seedtrees”,whicharephenotypicallysuperiortotherestof thestand.Treesshowingbasalsweep,sinuousorforkedstemsandheavyorhigh-angledbranchingshouldbeavoided.Inthiswayphenotypicsuperioritycanbeensuredinthemothertrees,althoughthereisnocontroloverthequalityof thetreesprovidingthepollen.Inordertomaintainvariabilitywithinabulkseedcollection,itisdesirabletocollectfromaminimumof 25-50mothertreesperstand,separatedfromeachotherbyadistancenotlessthanseedfall(FAO1969).Whenlargequanti-tiesof seedareneededfromstandsof limitedarea,collectorsmaybeforcedtorelaxtheaboverecom-mendations,butsuchrelaxationshouldberegardedasonlyatemporaryexpedient.

Withinastandselectedforseedproduction,earlyactionshouldbetakentoremovethepoorestpheno-types;thiswillimprovethephenotypicqualityof themale,aswellasthefemale,parents;atthesametimethegreatercrownroomincreasestheseedcroponeachof theremainingtrees.Morethanonethinningmaybeneeded.P.merkusii,likeotherpines,isastronglightdemanderandrespondswelltoearlythin-ning.Inyoungplantedstands,athinningregimehasbeenproposedforthecommonlyplantedpines,whichwouldreducestocking,afterfourthinnings,toabout140stemsperhaatdominantheight17m,equivalenttoanageof around12-15yearsonaveragesites(Willan1984).AlthoughinformationspecifictoP.merkusiiisnotavailable,itislikelythatthisgeneralprescriptionshouldbeapplicable.

Cone yield

Inthe1972collectionsofP.merkusiimadeinThailand,itwasfoundthattheaverageyieldof conespertreewas6kg(Granhof 1975).Keiding(1973)reportedanaverageyieldof 124conespertree(range80-180)ina1970collectionintheAtjehprovenanceof Sumatra.Inplantationsof AtjehorigingrowinginS.SumatraandS.Kalimantan,averageyieldsfrom400-600conespertreewererecordedatagesof 15to25(MartiniandSemadi(1980)).

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Crop Estimation

Acountof developingconescangiveausefulindicationof thecomingcrop.Estimatesof thepotentialseedcropbycountingfemaiestrobilimaybemisleading,if therearesubsequentseverelossese.g.frominsects,windorpoorpollination.InThailandnormalpracticeistosurveypotentialcollectionstandsaboutthreeweeksbeforeexpectedpickingtimetoassessthesizeandmaturityof thecrop(WisopakanandGranhof 1983).Apairof 7x50binocularsisausefulaid.Thenormalmethodistomakecountsonarepresentativesampleof seedtreesdispersedthroughoutthewholeseedsource.

Treesmaybeclassifiedsubjectivelyinthreeclassesas“poor”,“average”and“qood”,asdescribedforotherspeciesof conifers(e.g.Dobbs et al. 1976,Robbins1983a).If necessary,theyieldof seedsfromconesmaybeestimatedbycuttinglongitudinalsectionsof asampleof cones,usingaconecutterorma-chete(Dobbs et al. 1976,Robbins1983a).Theratioof fullseedsperconetofullseedsexposedonacutsurfaceinP.merkusiihasnotbeenreportedintheliteratureandmayvaryaccordingtoprovenance.Forothertropicalpines,P.caribaeaandP.oocarpa/tecunumanii,aratioof from10:1to20:1applies(Robbins1983a,1983b.Onlyfullseedsshouldbecounted;undevelopedseedsoccurringnearthetiporbaseof theconeshouldbeignored.

Maturity Indices

Sincetheseedingseasonisconcentratedwithinaboutfourweeksinthecontinentalprovenancesandthecollector’sobjectiveistocollectasmuchof thecropaspossiblewithinthisshortperiod,thecorrectuseof maturityindicesisessential.Recognitionof ripeconesisstillmoreimportantintheIndonesianprov-enances,whereripeandunripeconesmaybepresentatthesametimeinthesamestandandevenonthesametree.

Thesimplestmethodof estimatingconematurityisbycolourchanges,whichareusuallyaccompaniedbyhardeningof theconescales.InThailandtheoptimumtimeof collectionforP.merkusiiisreachedwhenthemajorityof coneshavechangedcolourfromgreentobrownishandsomehavestartedtoopen(Granhof 1975).

Maturitymaybeconfirmedbycuttingtest.Thegametophytictissue(“endo-sperm”)inpinespassesthrougha“milky”andthena“dough”stage;atmaturityitshouldbefirmandtheembryowelldeveloped.Specificgravityhasbeensuccessfullyusedtoestimateconematurityinanumberof temperatepines.Cones(andseeds)losemoistureastheymature,thereforematureconeshavealowerspecificgravitythanimmaturecones.

Flotationtestsinwaterorinvariousoilscanbeeffectiveindifferentiatingbetweenmatureconeswhichfloatandimmatureoneswhichsink.ThistestdoesnotappeartobecommonlyusedinP.merkusii.Inanothertropicalpine,P.caribaea,itwasfoundthat,if ¾of aconesamplefloatsinwater(SG=1.0),col-lectioncanstartintheareasampled;anyconewithSGof over1.14istooimmaturetobeworthcollect-ing(Hughes1981,citedinRobbins1983a).

Deliberatecollectionof unripeconeshassometimesgivenacceptableresultswithotherpinespeciesandmaybedictatedbylocalconditionse.g.theneedtofitinwithannualsowingdatesinthenursery.ItisnotsuitableforP.merkusii.IntrialswiththeZambales(Philippines)provenance,itwasfoundthattheper-centageof greenconeswhichopenedfullyaftersun-,oven-,orkiln-drying,variedfromlessthanonehalf

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tolessthanonetwelfthof thepercentageof ripebrowncones(Gordon et al. 1972).Cyclesof 80hours’drying,alternatingwith48hours’soakingandrepeated5or6timesoverafour-weekperiod,succeededinraisingthepercentageof openedgreenconestoapproximatelythesameasthatof thebrownconesafterasingledryingoperation,butwouldbefartooexpensiveforlarge-scaleuse.Germinationof seedsextractedfromgreenconeswasslightlyinferior(about10%)tothatfrombrownconesandtheirstoragecapacitywasalsoinferior.

Theseconclusionshavebeenclearlyconfirmedbyrecentresearchcarriedoutonconesof IndonesianracecollectedfromthreeplantationsitesinJava(Arisman1984,ArismanandPowell1986).ConeswerecollectedinJuneandJuly1983andwereclassifiedinthreecategoriesaccordingtocolour,(a)Brown,(b)Green/brownand(c)Green.Seedswereextractedbyvariousconetreatments.Brownand,toaslightlylesserdegree,green/brownconeswereconsistentlysuperiortogreencones.They(l)hadhigherpercent-agesof conesfullyopenedduringsun-drying;(2)producedlargerweightsandnumbersof seeds;(3)pro-ducedhigherpercentagesof fullseeds;(4)producedhigherpercentagesof fullseedswithwell-developedmegagametophytetissue;(5)producedseedswithhighergerminationpercentagesandvalues;and(6)pro-ducedgreaterproportionsof germinantsinthehigherseedlingvigourclasses.Seedyieldvariedfrom8.3seedspergreenconeto13.6seedsperbrowncone.Althoughthegerminationpercent(af ter22days)of seedsfromgreenconeswasover80%ineverycase,itwasconsistentlylowerthanthatof brownorgreen/browncones.Thespeedof germinationwasalsoslower,sothatthegerminationvalueof greenconeswassignificantlylowerthaneitherbrownorgreen/browncones.Green/brownconesgaveinterme-diateresultsbetweenbrownandgreencones.Everyeffortshouldthereforebemadetocollectonlyripeconesinthisspecies.

Collection Methods

Thenormalmethodof seedcollectionisbyclimbingstandingtreesandpickingtheripeconesbeforetheyopentodispersetheseeds.Amajorproblemincollectinginnaturalstandsisaccess.P.merkusiiissome-timesfoundinmountainouscountry,onlytobereachedbyfootwithsomehours’walkingfromroadside.Thustheclimbingmethodshouldavoidtheuseof heavyequipment.Useof ironclimbingspursfittedtoleatherboots,withsafetybeltandsupportinglineof terylene,helmetof glassfibreandheavyleatherglovesisthetechniquepresentlyinuseinThailand(WisopakanandGranhof 1983).Thetotalweightof thisequipmentis3kgmakingitparticularlysuitableforuseininaccessiblestandsinroadlesscountry.Whenthecollectorreaehesthecrown,heusestwocanvasbagsattachedtohisbeltandaspeciallyde-signedcollectionhook.Thisissharpenedonbothsidesandcanbeusedeitherforpullingorpushingoff thecones,whilstthecollectoriswithinthecrownthusavoidingthebreakageof twigs.Thehooksaremountedonlightironpipes,whichcanbeextendedtoalengthof about3m.

Instandsof medium-sizetreesaclimbercaninadaycolleetfrom6treeswithanaverageof 25-30kgof cones.

Plantationsandseedstandsareusuallymoreaccessiblethannaturalstands,buttheymayalsobeinsteepterrainunsuitableformechanizedcollectingmethods.InseedstandsinThailandverticalsteelpipelad-dersareused,securedtothebolebynylonstraps.Byattachinganumberof differentsectionsoneaboveanother,aheightof 18mcanbereached(WisopakanandGranhof 1983).Theuseof laddersavoidsthedamagetobarkandsapwoodwhichwouldresultfromclimbingthesametreeseveryyearbymeansof spurs.

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SeedorehardsarenormallyplantedongentIetopography.Intheseconditionsandif theorehardsarelargeinsize,amobileeolleetingplatformmaybeaneffieientmethodof eolleetion.InThailandtheAfron450skyliftisused.Thepickingplatformeanberaisedto5mandthepiekerhimself cancontroltheop-eration(WisopakanandGranhof 1983).Controlof theliftingmaybedonebythehandsorbythefeet;inthelattercasetheoperatorhashishandsfreetopickconesortocarryoutcontrolledpollinationintheseedorchard.

Cone Storage in the Forest

Whencollectionstakeplaceoveralongperiod,storageof conesintheforestmaybecomenecessary.Freshlycollectedconeshaveafairlyhighmoisturecontent,20-25%inripecones,40-50%ingreencones(Gordon et al. 1972).Bulkquantitiesof freshcones,if storedathightemperatureandhumidityforalongperiod,areverysusceptibletodeteriorationthroughtheactionof mouldsandotherfungiandthroughoverheatingduetoahighrateof respiration.Wellventilatedshelterisneededagainstrainanddirectsunlight,andconesstoredingunnybagsmustbewellspacedonracks.Carefulstorageof thistypeforalimitedperiodhasbeenshowntohavenodetrimentaleffectsonP.merkusiiinThailand.Infact,gunny-bagstoragefor7-8daysseemedtoinduceaquickermaturingof thecones,withoutanyreductionof ger-minationcapacity,incomparisonwithimmediateexposuretosundrying,whichresultedintheextractionof lessseedwithreducedviability(WisopakanandGranhof 1983).Ontheotherhand,threeweeks’sackstorageof Zambales(Philippines)seedappearedtocauseahighlossof seedquality,mainlythroughtheattacksof Dioryctriaseedborers(Gordon et al. 1972).

6. SEED PROCESSING

Precuring

ConesofP.merkusiirequireprecuringbeforeseedextraction.Asalreadymentioned,immediatesun-dry-ingof freshlycollectedconessometimescausesreducedseedyieldsdueto“case-hardening”.Thecase-hardeningconditioncanresultfromtheoutertissuesdryingtooquickly,beforetheinnertissuescanlosemoisture;theconescalesthenfailtoopenproperly.

ThesimplepracticeforprecuringP.merkusiiconesattheThai-DanishPineImprovementCenteristoplacetheminwell-spacedconebagsonracksabout50cmoff thegroundundershelter,toallowfreeaircirculation,andtoleavethemuntilallconeshaveturnedcompletelybrown.Thiswilltakefrom7-14days(WisopakanandGranhof 1983).Indonesianresearchexperienceonprecuring/coneextractionissimilarandisdescribedbelowunder“Conedryingandseedextraction”.

Cone Drying and Seed Extraction

MatureandprecuredconesofP.merkusiiopenrelativelyeasily.TrialsinThailandshowedthat,providedthereisclearsun,exposureofP.merkusiiconestosundryingmaybediscontinuedafter3dayswithalossof only6%of theseedtotalretainedinthecones,comparedwith6daysforP.kesiya(WisopakanandGranhof 1983).Ontheotherhand,P.merkusiiconesripenlaterthanP.kesiyainThailandandinsomeprovenancesextractionmaycoincidewiththestartof therains,withovercastskies,reducedtemperature

GV = ΣDGS x GPN 10

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andincreasedhumidity,whichrenderextractionmoredifficult.

InZambia,incontrast,conesofP.merkusiiarereportedtoopenmuchlaterthanotherpinesplantedandpresentfewerproblemsinextraction(Mubita1984).InThailandconesarespreadontrayslxlmsquare,with10cmhighwoodensides,abottomof lsq.cm.wiremeshandacoverof polythenesheeting(Bryndum1975,WisopakanandGranhof 1983).Aftertheconesopen,theseedsfallthroughthewirenettingintoacanvassuspendedunderthetrays,fromwhichtheyarecollected.Inthecaseof smallsampIeswhichmustbekeptseparate,e.g.forprovenancetrials,smallertraysareused,fromwhichtheseedsfallthroughametalfunnelintoabagattachedtotheout-let.Thetraysaremountedonwoodenscaffoldingataconvenientheight.Thepolythenesheetingservestotrapthesun’sheatandraiseconetemperature,aswellasexcludingrain.

Theresearchof ArismanandPowell(1986)oncollectionof brownandgreenconeshasalreadybeende-scribedunder“Maturityindices”.Thesameauthorsalsoinvestigatedtheeffectsof differentmethodsof seedextraction.Theextractiontreatments,whichwereappliedtobrown(B),green/brown(G/B)andgreen(G)coneswere:

(l) Longitudinalsplittingof conesintofoursectionswithaknife,followedbymanualpickingoutof seeds(SC).Thiswasthetechniqueusedincurrentpractice.

(2) Immediatesun-dryingof conesforuptotwoweeks(withoutpreviousstorage),withdailyremovalof seedsandcone-stirringfourtimesaday(NS).

(3) Sun-dryingof cones,precededbytwoweeksof storageinsuspendedhalf-filledgunnybagsunderawoodenroof,withcompleteshadeandfreeaircirculation(S2).

(4) Sun-dryingof cones,precededbyfourweeksof storage(S4).

Theauthorsfoundthatimmediatedryingof brownconesgaveaslightlyloweryieldof seedsthanthepre-dryingstoragetreatmentsandthiseffectwasmoremarkedingreen/brownandespeciallyingreencones.Storagealsoimprovedthegerminationspeedandgerminationvalue.Inpracticalterms,itwascon-cludedthatimmediatedryingwasanacceptabletreatmentforbrowncones,butthatbothgreen-brownandgreenconesbenefitedsignificantlyfrompre-dryingstorage.

Thesplit-coneseedextractionmethodyieldedweightsof seedsfromconesof allcoloursequivalenttothatof brown(fullymature)conesextractedbysun-drying.Numbersof seedsproducedbythismeansfromgreen(immature)coneswerealsogreaterthanthosefromsun-dryingtreatmentof greencones.Itseemsthatsuddenexposureof green/brownandgreencones,withtheirrelativelyhighmoisturecon-tent,tosun-dryingresultedincasehardeningof coneseales.However,ArismanandPowell(1986)con-cludethatthesplit-conemethodhastoomanydisadvantages.“Themainproblemisthatconesatvariousstagesof maturityaretreatedatthesametimeandthisleadstoextremevariabilityinseedlotquality.Itisnaturalthatunsupervisedconepickers,whoalsodotheextractionandselltheseedsbyweight,willincludegreencones.Greenconesareeasiertocutandyieldfewerseeds,buttheseedsweighasmuchasgreaternumbersof seedsfrommorematurecones.Thus,lessworkisneededtoproduceequivalentweightof seeds.Unfortunately,theseedsfromimmatureconeshaveahighmoisturecontent(hencetheequivalenceinweightwithgreaternumbersof seedsfrommorematurecones),frequently,still-milkytis-sues,softseedcoatsandseedwingsthatarehardtodetach.Duringextractiontheseimmatureseedsareeasilyinjured.Theyarealsoeasilyinjuredduringrubbingonbambootrays,whichisthemethodusedtodetachthewings”.

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Thefollowingfigures,extractedfromthemuchfullerdatarecordedbyArismanandPawelI(1986),indi-catetherangeof resultsobtainedfromthisresearch:

Cone Number of seeds extracted

per coneGermination value *)

Cone colour Class Cone colour Class

B G/B G Mean B G/B G Mean

SC 13.1 12.7 11.5 12.4 66 58 43 56

NS 12.1 9.4 4.6 8.7 76 55 50 60

S2 13.2 10.5 7.5 10.4 87 61 58 69

S4 16.1 13.5 9.5 13.0 92 69 57 73

MEAN 13.6 11.5 8.3 11.1 80 61 52 64

*)Usingtheformulaof DjavanshirandPourbeik(1976):

where GV=germinationvalue GP=germinationpercentattheendof thetest DGS=meandailygerminationspeed,obtainedbydividingthecumulativegerminationpercent bythenumberof dayssincesowing ΣDGS=thetotalobtainedbyaddingeveryDGSfigureobtainedfromthedailycounts N=thenumberof dailycounts,startingfromthefirstdayof germination

Itisconcludedthatstorageforupto4weeksbeforesun-dryingisbeneficialforbrownconesandessentialforgreen/brownandgreencones,incaseswhereshortageof maturebrownconesmakesitnecessarytousetheimmaturecones.

Afurtheraidtofullerextractionistoincorporatefrequentmanualconestirringinthetraysortotumblethedryconesinarotatingdrumcoveredbylsq.cm.wiremesh.Thestandardpracticenowistoleavetheconesfivedaysinthetraysunderpolytheneandthentumblethemforseveralminutesinthedrum.Inonetrialitwasfoundthatthetumblingoperationextractedatleastasmanyseedsasafurtherthreedays’exposureinthetrays,withnolossingerminationcapacity.Extractedseedsshouldberemovedfrequentlyfromthecanvasunderthetrays,topreventoverheating.

Pinusmerkusiiseedsmayalsobeextractedbyartificialheat.Satisfactoryresultswereobtainedby80hours’dryingattemperatureswhichweregraduallyincreasedfrominitial30°Ctofinal50°C.Highertem-peraturesforshorterperiodshavealsobeenused:50°Cfor6hoursplus60°Cfortwohoursplus70°Cfortwohours(Gordon et al. 1972).

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Dewinging

P.merkusiiseed,likeotherpineseeds,hasawing3-4timesthelengthof theseed.Inordertomakeseedprocessingandnurserysowingeasier,thewingisusuallyremoved.Forsmallquantitiesof seedforex-perimentalpurposes,e.g.species,provenanceandprogenytrials,dewingingmaybedonegentlybyhand,eitherbyrubbingseedbetweenthehandsoragainstascreenorroughenedsurface,orbyhandrubbinginaclothbag.

Forlargequantitiesof seed,mechanicaldewingingmaybeused.Averticalcylinderdewinger(Damas)isusedinThailand.Thecapacityis0.15cu.m.or150liters.Itcanhandle11kgof seedswithwingsperhour,withnodamageobservedtotheseed(WisopakanandGranhof 1983).Thismachinedewingstheseedthroughtherotationof aconicalsnailwhichrubstheseedsagainsteachotheraswellasagainstthewallof thecylinderandthenpressesthemthroughthenarrowcylinderoutlet.Rotationof thesnailanbeadjustedtodifferentspeeds.

Othertypesof mechanicaldewingerhavebeenusedsuccessfullyforpineseedsandwouldprobablyworkwellwithP.merkusii.Drumsorcementmixersarecommonlyused,rotatedmanuallyorbymotor.Waterissometimesaddedtoreducemechanicaldamage.Thus,inHonduras,seedswithwingsarefirsttumbledfor15minutes,wateristhensprinkledontheseedsatarateof aboutonelitreof waterfor50litresof seed,andtumblingiscontinuedforafurther45minutes.Thismethodworkswellwiththetwotropicalpines,P.oocarpaandP.caribaeavar.hondurensis(Robbins1983a,1983b).

Cleaning

SoundseedsofP.merkusiimaybedistinguishedfrominertmatterandsterileandemptyseedsbysize,shapeandspecificgravity.Screeningandsievingmethodsseparateseedsandotherparticlesbysize,whileliquidflotation,blowingandwinnowingmethodsseparatebyspecificgravity.

Cleaningof smallresearchsampIesof pineseedby“SouthDakota”seedblowerisapracticalmethodusedwithsuccessattheThai-DanishPineImprovementCenter.Throughairflowof varyingspeed,seedlotscanbeseparatedintopureseedandinertmatter.Likewisefullseedmaybeseparatedfromimmature,emptyordamagedseed(WisopakanandGranhof 1983).

Forlargequantitiesof seedinThailandandthePhilippines,handwinnowingbymeansof flatbasketsorbambootraysasusedforwinnowingrice,isaneffectivecleaningmethod(Cooling1967,Bryndum1975,WisopakanandGranhof 1983).Itavoidstheuseof expensive,importedequipment.InThailandtheinitialwinnowingisfollowedbyasecondwinnowingof thediscardedfraction.Thisresultsnotonlyintheremovalof extraneousmatterbutinanimprovementinthepercentageof fullseedsintheretainedfrac-tion.Oneoperatortakesabout8minutestowinnowlkg.

Winnowingorblowingmaybeprecededbyasievingorscreeningoperationtoseparatematerialwhichdiffersappreciablyfromtheseedinsize.Sievingmaybemanualormechanical.Twomeshsizesshouldbeused;thelargershouldallowtheseedtopasswhileretainingbiggermaterial,whilethesmallerretainstheseedbutallowssmallerfragmentstopass.

Seedmoisturecontentmustbetestedbetweenprocessingandstorage.If extractionisdoneinthedryseasonbysun-dryinganddewingingisdonedry,seedsnormallyhaveamoisturecontentlessthan8%

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(freshweightbasis)andaresuitableforstorage.ForanumberofP.merkusiiprovenances,collectionandextractiontakeplaceafterthestartof therainyperiod,whenairhumidityisrising,andfurtherdryingof theseedswillbenecessary.Thesameappliesif moistdewinginghasbeendone.If spellsof sunshineoccur,seeddryingcanbedoneeasilybyspreadingtheseedsonasheetinthesun,abouttwoseedsthick,andrakingfrequently(Robbins1983a,1983b).If sun-dryingisnotpossible,anelectricdryingovenwithforceddraftventilationmaybeused(WisopakanandGranhof 1983,Robbins1983a,1983b).

Seed Yield

The1972collectionofP.merkusiiseedinTailandproduced9gof seedperkgof conesor54gof seedpertreeonaverage(Granhof 1975).Otherfiguresquotedareabout1200gof seedperl00litresof conesinThailand(WisopakanandGranhof 1983)andabout650gof seedperl00litresof conesfromtheZambalesprovenanceinthePhilippines(Gordon et al. 1972).

Withinthespeciesthereismuchvariationaccordingtoprovenanceandyear.Keiding(1973)reportedthat30fullseedsperconecouldbeexpectedinanormalyearintheSumatranAtjehprovenance.In1970,inapoorseedseason,theyieldof seedsinAtjehwasonly7gpertree.MorerecentlyMartiniandSemadi(1980)reportedtheaverageyieldof seedsperconefromplantationsaged15-40yearsgrowingonlowlandsitesinS.Sumatra,S.KalimantanandW.Javaas5seedspercone,comparedwith20seedsperconefromhighlandsitesinSumatra.InthePhilippinesthe1968cropyieldaveraged11seedspercone(Wormald1970).

7. SEED STORAGE AND TREATMENT P.merkusii seedisclassifiedasorthodox.Inthepastithashadthereputationof quicklylosingviabilityduringtransportandstorage(Cooling1968,BurleyandCooling1972).Thismaybeduetothefactthatthecollectionseasonoftencoincideswithaperiodof relativelywetweather,sothatthemoisturecontentof freshlycollectedseedishigh.Anaddedfactorinthecaseof Sumatranprovenancesisthehabitof someconesripeningthroughouttheyear,sothatanyconecropharvestedmayinadvertentlyincludeaproportionof immaturecones.Providedthatonlymatureconesarecollectedandthatmeticulouscareistakenintransport,extractionanddrying,P.merkusiiseedshouldstoreaswellasanyothertropicalpine.

Lossof viabilityinorthodoxseedsislargelygovernedbytherateof respiration.Forstorageoverseveralyears,therefore,anymeasureswhichreducetherateof respirationwithoutotherwisedamagingtheseedarelikelytobeeffectiveinextendinglongevity.Thesemeasuresincludeloweringof moisturecontent,loweringof temperatureandexclusionof oxygen.

Attheseedsectionof thePineImprovementCenterinChiangMai,Thailand,routinestoragepracticeistodrytheseedtolessthan8%moisturecontent(freshweightbasis),packintwosealedpolythenebags(thickness5milor125microns),labelbothinsideandoutsidethebagandstoreinacoolroomat+4_5°C(WisopakanandGranhof 1983).Differentsizesof polythenebagareused,varyingfrom100gto2kgcapacity,inaccordancewithexpectedneeds,allowingretrievalof anydesiredquantityfromthestore

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withoutopeningthepacketsandexposingtheseed.ThestorageroomsarecooledbyaSabroe/Atlasair-cooledcondensingunitfortworooms,withoneevaporatorandindependentcontrolsforeachroom.Theroomsincorporate20cminsulationintheroof and10cminthewalls.Fromresearchondifferentfactorsaffectingseedlongevityitwasfoundthat,overthe4-yearperiodof thetrial,therewasnoadvantageinstoringP.merkusiiseedatsub-zerotemperatures,comparedwiththestandard+4or5°C.P.merkusiiappearedmoresensitivetomoisturecontentthanP.kesiya,forexampleP.kesiyastoredwellforuptooneyearatroomtemperature(20°-30°C)regardlessof thetypeof containerused,whichincludedclothbags,whereasequallygoodresultswithP.merkusiiatroomtemperaturewereobtainedonlywhentheseeds,afterdrying,werestoredinsealedbottleswithsilicagel.

Storageforatleastfouryears,withretentionof highgerminability,shouldpresentnoproblemaslongasconesarematureandproperlyhandledduringtransportandextraction,andseedsaredriedtobelow8%moisturecontent(freshweightbasis),placedinsealedcontainersandstoredat4-5°C.

Experimentswithseedsof localPhilippineprovenancesclearlydemonstratedthevalueof storageatlowtemperature(+2°C).Seedsplacedincoldstoragetwomonthsaftercollectionhadretainedfullgermina-bilityafter12months’storage,inthecaseof matureseedsgerminationwasactuallyimprovedfrom59%to73%(Wormald1970).Whenstoredatroomtemperature,hovever,germinationof matureseedsdroppedfrom59%to13%after6monthsandtol%after8months,whilegerminationof seedsfromgreenconeshaddroppedtol%in6months,Theexperimentshowedthatseedsfromgreenconeswouldgivesatisfactorygerminationif properlystoredbutwoulddeterioratemorerapidlythanseedsfromma-turebrownconesif givenlessthantheoptimumstorageconditions.

DormancyhasnotbeenobservedinP.merkusiiandnospecialtreatmentisneededtoinitiategermina-tion.Testsof prechillingonseedsof Zambales(Philippines)provenancedidnotincreasegermination,onthecontrarytheprechilltestsalmostinvariablyproducedgerminationfiguresbelowthoseof theun-treatedcontrols(Gordon et al. 1972).

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8. SEED TESTING

Sampling

Standardsamplingmethodsshouldbeusedtoensurethatthesamplestestedare,asfaraspossible,repre-sentativeof eachseedlot.

InThailand,whenaseedlothasbeenextractedandcleaned,itisthoroughlymixedbeforedrawingsamplesby“Boerner”samplerfortesting.Thisdeviceconsistsof acylinderwithafunnelatthetop.Openingof avalveatthebottomof thefunnelreleasestheseedwhichflowsdownthefunnelandstrikesaconewhichisdirectlyunderthecentreof theopening.Aroundthebaseof theconeare30outlets.Whentheseedfalls,itisseparatedinto30individualstreams,mergingagainintotwostreamsemptyinginto2pans.Byrepeatingthisprocedureseveraltimes,eachtimeusingtheamountemptiedintooneof thepansonly,thesamplesizeisgraduallyreducedbyrepeatedhalving,whilebeingthoroughlymixedallthetime(Wisopa-kanandGranhof 1983).

Purity and Pure Seed Weight

PurityandpureseedweightmaybeassessedusingnormalISTAprocedures(ISTA1985)andapplyingtheappropriatedefinitionsforpureseedandimpurities.DataforP.merkusiiarenotavailable,butanaveragepurityof over95%,whichisapplicabletoothertropicalpines(WisopakanandGranhof 1983,Robbins1983a,1983b),maybeassumed.

Figuresforseedweightareavailablefromseveralcountries.Theydemonstratedifferencesassociatedwithprovenance;sameIndonesianprovenanceshavetwiceasmanyseedsperkgassameof thecontinentalprovenances.

No.of seeds per kg

Average Range

Thailand - two eastern provenances l) (Surin and Sri Saket)

Thailand - 19 other provenances l)

The Philippines - two Zambales provenances 2) The Philippines - two Mindora provenances 2)

Java (plantations of Sumatran origin) l)

Sumatra - Atjeh provenance 3)

Vietnam 4)

Kampuchea 4)

Sources:

l) Wisopakan and Granhof 1983 2) Turnbull 1972 3) Cooling 1968 4) Whitmore and Geary 1972.

42,000

29,400 45,000 39,100 50,000

58,900 32,500 30,400

40,200 - 44,000

24,300 - 38,500 43,700 - 46,300 37,500 - 40,700

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Moisture Content Pinusmerkusiiissuitableforthestandardmethodof testingmaisturecontentprescribedbyISTA,i.e.weighingof tworeplicatesamplesof about5geach,dryinginanovenataconstanttemperatureof 103°C±2°for17±lhours,coolinginadesiccatorfor30-45minutesandthereweighinginanatmos-pherewithlessthan70%relativehumidity.Lossof weightisthenexpressedasapercentageof thefreshweightof thesamplestogivethemaisturecontentof theseeds,viz.:

Moisture content weight before drying less weight after drying x 100 weight before drying

Morerapidbutslightlylessprecisemeasurementsof moisturecontentcanbemadebyanelectricmois-turemeter.InthePineImprovementCenterinThailandanautomaticmoisturetester“SuperBeha”hasbeenusedsuccessfully.Thedeviceisbasedanthemeasurementof thedielectricconstantataveryhighradiofrequency,toensureafineaccuracyof measurement.Thedailycheckingof thecalibrationagainstaquantityof glassbeadsof aknowndielectricconstantensuresauniformandaccuratedeterminationof themoisturecontentinhomogeneausseed.Afeatureof the“SuperBeha”istheinclusionof ampleinsu-lationbetweenthecondenserplatesandthesamplesundertest.Satisfactoryresultshavebeenobtainedinmeasuringmoisturecontentsupto29%(WisopakanandGranhof 1983).

Germination Tests

ThemostrecentpublicationfromISTA(1985)prescribessuitableconditionsforgerminationtestingofP.merkusii.Theseconditionsare:seedsplacedantopof papersubstrate,exposedtoalternatingtempera-turesandlightconditions(8hours30°Cwithlight/16hours20°Cwithoutlight);first,germinationcount7daysaftersowing,finalcountafter21days.Relativehumidityshouldbemaintainedat90-95%aroundtheseeds.Germinationtestsshouldbeperformedonthe“pureseed”fractionof theseedsample.

InthePineImprovementCenterinThailand,the“Jacobsen”apparatus(Copenhagentank)hasbeenusedsuccessfullyforgerminationtestingofP.merkusii(WisopakanandGranhof 1983).Theapparatusprovidesstandardizedgerminationconditionswithautomaticcontrolof alternatingtemperaturesinthewaterbathintowhichtheendsof thefilter-papersubstratedip.Atotalof 400seedsareused,dividedintoreplicatesof 25or50seedseach,placedanthefilter-paperandcoveredbyabelljar.Overheadartificialilluminationof 750-1250luxissuppliedbyfluorescentlight.

Analternativemethodof testingP.merkusii,whichisalsousedforroutinesowingfornurseryplantproduction,istousemoistblottingpaper56x22cm(WinaiSirikul1975).Thepaperisfoldedwith9fur-rows,eachof whichis1.5to2,cmdeep,leavingabouthalf of thepaperunfolded.Seedissowninthefur-rows,exceptforthemiddleone,at35seedsperfurrowor280perpack.Tosuckthewaterintothepack,awickisplacedinthemiddlefurrow.Aftersowing,thepaperisfoldedup,theunfoldedpartwrappedrounditandsecuredwithrubberbands,andseedregistrationnumber,experimentnumberandsowingdatearemarkedanthepackwithwaterproof colour.Theseedpacksareplacedanagerminationtray,withwickendsdippingintoawaterbathbutwithoutthepacksbeingsoakedbydirectcontactwiththewater.Thetraysarefinallystackedindoorsanshelves.

Thismethodworkswellbutgivesgerminationestimatesabout10%lowerthanthoseobtainedfromtheJacobsenapparatus(WisopakanandGranhof 1983).ItoccupiesmuchlessspacethantheJacobsenmeth-od.Theuseof plasticboxeswithtight-fittinglids,toretainthemoistureinthesubstrate,asdescribedbyRobbins(1984)wouldbesuitableforP.merkusii.

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Germinationstarts8-10daysaftersowing.SeveralauthorsreportpoorgerminationforP.merkusiiseeds,oftenlessthan40%,sometimeslessthan20%(Cooling1968,Turnbull1972,BurleyandCooling1972,Keiding1973).Insomecasesthepoorgerminationcanbeexplicitlylinkedtothecollectionof unripecones,inothersdeteriorationmayhavebeenassociatedwithpoorcontrolof moistureandtemperatureconditionsduringtransit.Withgoodhandlingof seedfromripecones,germinationof over70%shouldbepossible.Intestsof Zambales(Philippines)seed,germinationvariedbetween66and84%(Gordon et al. 1972).MartiniandSemadi(1980)foundthatseedsfromthreelowlandplantationsinIndonesiawhichaveragedonly5seedsperconehadalowgerminationof average27.1%(range22.3-33.5%),whileseedsfromfourhighlandsiteswhichaveraged20seedsperconehadagerminationof average66.2%(range49.3-75.6%).Asoftenoccurswithotherspecies,lowseedyieldwasassociatedwithpoorseedviability.

Rapid Tests of Viability

Cutting test.Thesimplestviabilitytestingmethodisvisualinspectionof seedswhichhavebeencutopenwithaknifeorscalpel;theseedshouldbesoakedfor24hourstofacilitatesectioning.Seedswithmilky,unfirm,mouldy,decayed,shrivelledorrancid-smellingembryoandabortedseedsthathavenoembryocanbejudgedasnon-viablewithoutmuchdifficulty(Bonner1974).Fullseedswithfreshwhitetissuesandawell-developedembryoarelikelytobeviable.Itisnotalwayspossibletodistinguishmoribund,recentlydeadorrecentlyinjuredseedswhichstillappearthesameassoundones.Thecuttingtestisparticularlyusefulforquickestimatesof viabilityduringcollectionandprocessing.

InThailandtheTetrazolium testisusedinconjunctionwiththeFossElectric“Vitascope11100”machine.Thisusesavacuumatatemperatureof 45°Candtheabsorptionprocessisthereforegreatlyaccelerated;seedstainingisusuallycompletewithinhalf anhour(WisopakanandGranhof 1983,Knudsen1982).

Thetestdependsontheabilityof theemzymesinlivingtissuetoreducethecolourlesstetrazoliumsalttotheredchemicalformazan.Fullystainedembryoscansafelybeassumedtobecapableof germinationandunstainedembryostobedead.Problemsariseintheintermediatecaseswhereembryosarepartiallystained.Insuchcasestheseedanalystneedsconsiderableexperienceinordertointerpretthedegreeof stainingintermsof germinationcapacity.

Radiographic testsof viabilityhavebeenusedsuccessfullyforanumberof pinespecies.TheX-raymethodpermitsthedetectionof emptyseeds,machanicaldamageandabnormallydevelopedinternalseedstructures,measurementof thethicknessof theseedcoatand,whencombinedwithacontrastagent,as-sessmentof seedviability.Thedevelopmentof softX-rayequipmenthasgreatlysimplifiedtheoperationandaprocessedX-rayprintmaybeobtainedinafewminutes(Belcher1973).

TheX-raymethodisausefuloneandislikelytoplayanincreasingroleinseedtesting.Earliermodelsof X-raymachineswereexpensive,butrecentmodels,particularlyfromJapan,aremuchcheaper.Improve-mentsinphotographicfilmsandpaperhavespeededuptheprocessandsimplifiedtheinterpretation.Be-sides,therearenowpossibilitiesforusingnon-toxicwater,insteadof toxicchemicalsasacontrastagentfortestingseedviability(Simak1982).

Kamra(1984)comparedestimatesof germinabilitybytheX-raycontrastmethodwithactualgermina-tioninaJacobsenapparatus,usingP.kesiyaandP.merkusii.Themethodusedwas:16hours’soakinginwater,superficialdryingbyfilterpaper,lhour’ssoakingin40%aquoussolutionof sodiumiodideinthedark,washinginrunningwaterfor1-5minutes,dryinginanovenat70°Cfor90minutes,X-rayphotog-

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raphy.Detailsof photographywere:KV14,mA5,focus-filmdistance50cm,exposuretime10seconds,filmAgfaGevaert“StructurixD7”,developedinStructurixDeveloperG-127,fixedinUniversalFixativeG-321.

In4sampIesofP.merkusii,whichshowedgerminationbetween73and87%ontheJacobsenapparatus,theestimatesbyX-rayrangedbetween-2and+5percentagepointsof germination.Intwosampleswithlowergermination(48and59%theestimatesbyX-raywere9and10percentagepointshigher.Theshapeof thegerminationcurvessuggeststhattheremighthavebeenaclosercorrelationif germinationcountshadbeencontinuedbeyondthe21daysof thetest.WhereasP.kesiyasamplesinthisseriesof experimentshadallcompletedgerminationin12-16days,inP.merkusiisomeseedswerestillgerminatingattheendof the21-daytestperiod.

9. REGENERATION PRACTICES

Nursery Propagation

NurserypracticeforP.merkusiifollowsgeneralpracticefortropicalpinessummarizedbyNapierandWillan(1983).P.merkusiiisoneof thespeciescoveredbytheaccountsof ThailandnurserypracticecontainedinWinaiSirikul(1975)andLloyd,HavmøllerandGranhof (1980).ReferencestoP.merkusiinurserypracticearealsomadeinCooling(1968)andPaul(1972).

Nurserystockisnormallyraisedinindividualcontainers,oftenpolythenetubes,sometimesinbedsfor“ball-planting”(i.e.withacubeorcylinderof soilattachedtotheroots).P.merkusiiisslower-growinginthenurserythanmostothertropicalpines.Forprovenanceswithoutagrassstage,8-9monthsshouldbesufficienttoraiseplants20-25cminheight(Cooling1968).Forgrassstageprovenances,aperiodof about12monthsisnecessary(Paul1972,Lloyd et al. 1983);forhigherandcooleraltitudesinZambia15monthswasfoundtobeappropriate(WhitmoreandGeary1972).Eventhentheplantswillprobablynotexceed10cminheight.Theseprovenanceshavetobeplantedoutwhilestillinthegrassstage;anyattempttokeeptheplantsinthenurseryuntiltheyhavegrownoutof thegrassstagewouldbeexcessivelyextrava-gantincontainersize,timeandcost.

ExperienceinThailandshowedthatP.merkusiirespondedlesstofertilizersinthenurserythandidP.car-ibaea,P.oocarpaorP.kesiya.Italsoprovedthemostsensitivetofertilizerburn.NormalpracticeherehasbeentogrowP.merkusiiinlargerpots(10x15cmlayflat)foralongerperiod(12months)thantheotherpinesandtoapplybetween1/3and½theamountof fertilizerrecommendedforthem.

Direct Sowing

Thismethod,whichusuallyincorporatesthepelletingof theseedswithinsecticideandrodent/birdrepellent,hasbeenusedonaconsiderablescaleforpinesintheSouthernUSA.ItdoesnotappeartohavebeenusedforP.merkusii.

Directsowingrequiresmuchgreaterquantitiesof seedthanuseof nurseryplants.Evenif seedisavail-ableinlargequantitiesandatlowcost,afforestationbyplantingisusuallypreferred,becauseitismorereliable,producinghigherinitialgrowthratesandfargreateruniformityinbothstockingandgrowth.

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Natural Regeneration

NaturalregenerationinseveralcountrieshasbeendescribedbyCooling(1968).Seedlingsoccuringreatestnumberswheremineralsoilisexposed,asforexamplealongoldextractionpaths,erodedslopes,roadverges,landslipsorrecentvolcanicdetritus.Thesetypesof siteprovideanidealcombinationof fulloverheadlight,freedomfromcompetitionfromhardwoodsandgrassandfreedomfromfire.Highsoilfertilityisnotneces-sary;oneexcellentexampleof regenerationwasseenonsubsoilexposedafteralltop-soilhadbeenremovedbybulldozer.Soilfertilityoftenhasanegativeeffectonpinesbecauseitfavoursthemorenutrient-demand-inghardwoods.

InthedriercontinentalareasP.merkusiigrowsinmixturewithdrydipterocarpspeciessuchasDiptero-carpusobtusifolius.Inmoisterareasitcannotcompetewithclosedhardwoodforestandoccursonlyinpatchesorgroupsonlandpreviouslyclearedbycultivationorfire.Becauseconditionsforsuccessfulre-generationtendtobelocalandof shortduration,pinegroupsareoftenmoreorlesseven-aged.

P.merkusiicancompetewithgrass,brackenetc.providedthatitisnotsubjecttoanexcessivedegreeof fire.Successfulregenerationamonggrassmaybeseen,forexample,insmallenclavesprotectedfromfirebysurroundingclosedforestorroads.TheSumatranprovenances,withnograssstage,appeartocompetemoresuccessfullythanthegrass-stagecontinentalprovenances.Naturalregenerationof thelatterprovenancesoftentakes3-5yearsbeforeitbeginstomakerapidheightgrowth(Cooling1968).

NocasesareknowninwhichmanagednaturalregenerationisusedasasystemforregeneratingP.merkusiiforests.

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