DOMESTICATION & CENTRES OF ORIGIN OF CULTIVATED

PLANTS

•  Domestication•  Thepresentdaycultivatedplantshavebeenderivedfromwildweedyspecies.

•  Thefirststepinthedevelopmentofcultivatedplantswasdomestication.

•  Definition:-domesticationistheprocessofbringingwildspeciesunderhumanmanagement.

•  Whichbeganover11000yearsago,whenhumansbeganagriculture.

•  Thefirstdomesticatedplantswerecereals,legumesandotherspeciesusedfortheirfruitsorroots.

•  Mostofthecropsweredomesticatedbyprehistorichumans.

•  Theyknowinglyorunknowinglyselectedthespecieswhichhasthecharacteristicstheyhaveaccordingtheirneeds.

•  Eventuallycropplantsaredivergedfromtheirwildancestralspeciessoremarkablythattheyareclassifiedaswilddistinctspecies.

•  Insomecasestheirwildancestorsarenoteaslyidentifiable.

•  Domesticationofwildspeciesislikelytocontinue.

•  Anotablecaseofrecentandcontinuingdomesticationrelatestoseveralplantspeciesfortheproductionofbiofuel.

•  Eg:-Jatrophacurcas•  AmemberofEuphorbiaceaefamily,cultivationisbeingpopularizedsinceoilextractedfromitsseedsisusedtoproducebiodiesel.Thisplatalsohasmedicinalvalue.

•  Whichissuplimentedupto5%ofdiesel.

•  Almostallthecharactersofplantspecieshavechangedduetoaccumulationofspontaneousmutations.

•  Thecharactersthatshowmoredistinctchangesarethosethathavebeentheobjectsofselectionandarestillplantbreedingobjectivesinmanycultivatedspecies.

•  Someimportantchangesthathavebeenoccurredunderdomestication:-

•  Eliminationorreductioninshatteringofpods,inmostofthecultivatedspecies.

•  Eliminationofdormancyhastakenplaceinseveralcropspecies.Lackofdormancyisaprobleminbarley,wheatetc.

•  Decreaseintoxinsorotherundesirablesubstanceshasoccurredincrops.Thebitterprincipleofcucurbitaceousplantsprovideanexampleofthis.

•  Planttypehasbeenmodified.Thecultivatedplantshowsalterdrtillering,branchingleafcharactersetc.

•  Decreaseinplantheight,oftenassociatedwithachangefromindeterminatetodeterminatehabitat.

•  Insomespeciesanincreaseinplantheightcanbeseen.eg:-jute,sugarcaneetc.

•  Lifecyclehasbecomeshorter.particularlyincropslikecotton(Gossypiumsp.).

•  Increaseinsizeofgrainsorfruits.•  Increaseineconomicyield.•  Inmanycropsasexualreproductionhasbeenpromotedunderdomestication.

eg:-Solanumtuberosum,Ipomeabatatus•  Preferenceinpolyploidy,whilecdiploidcounterpartsarepresentinnature.eg:-wheat.

•  Shiftinthesexformunderdomestication.inmanydioeciousfruittrees,bisexualformshavedevelopedunderdomestication.selfincompatibilityhasalsobeeneliminatedinseveralcropspecies.

Centresoforigin•  Itisgenerallyacceptedthatcultivatedplantswerenotdistributeduniformlythroughouttheworld.

•  Eventodaycertainareasshowfargreaterdiversitythanothersforcertaincultivatedcropsandtheirwildrelatives.

•  In1926Vavilovproposedthat,cropplantsareevolvedfromwildspeciesintheareasshowinggreatdiversityandtermedthemasprimarycentresoforigin.

•  Later,thecropsmovedtootherareasprimarilyduetohumanactivties;theseareareaswhichgenerallylackrichnessinvariationwhichisfoundinprimarycentresoforigin.

•  Secondarycentresoforigin:-areas,inwhichplantsshowconsiderablediversityofformsalthoughtheydidnotoriginatethere:suchareasarecalledsecondarycentresoforigin.

•  TheconceptofcentresoforiginwasgivenbyVavilovbasedonhisstudiesofavastcollectionofplantsattheinstituteofplantindustry,Leningrad.

Conceptofcentresoforigin•  TheconceptofcentersoforiginwasfirstproposedbytheRussianscientistNikolaiVavilov(1887-1943).

•  VavilovheadedwhatwastobeeventuallynamedtheVavilovAll-UnionInstituteofPlantIndustryfrom1920to1940.

•  Oneofhismissionswastocollectcrop-relatedgermplasmforuseinnationalplantbreedingprojects.

•  Duringhisexplorations,Vavilovobservedthatcropdiversitytendstobeconcentratedaroundspecificregions.

•  Heproposedthattheseconcentrationsofhighvariabilityindicatedtheregionswheredomesticationofthesecropsbegan.

•  Thisconceptwentagainsttheprevailingviewthatcultivationofplantsstartedrandomlyallovertheworld.

KindsofevdencethatVavilovused;•  Archaeological•  plantremains•  Livingplants•  DNA,proteins,morphology,biochemistry•  Ecology,distributions•  Linguistic:-namesofthecropindifferentlanguages

•  Locatingtheoriginofcropplantsisbasictoplantbreeding.

•  Thisallowsonetolocatewildrelatives,relatedspecies,andnewgenes(especiallydominantgenes,whichmayprovideresistancetodiseases).

•  Knowledgeoftheoriginsofcropplantsisimportantinordertoavoidgeneticerosion,thelossofgermplasmduetothelossofecotypesandlandraces,lossofhabitat(suchasrainforests),andincreasedurbanization.

N.IVavilov•  NikolaiIvanovichVavilovForMemRSwasaprominentRussianandSovietbotanistandgeneticistbestknownforhavingidentifiedthecentresoforiginofcultivatedplants.

•  Born:25November1887,Moscow,Russia•  Mainbooks:Fivecontinents,Originandgeographyofcultivatedplants.•  Field:botanyandgenetics•  Notableawards:Leninprize,Fellowoftheroyalsociety.•  Hewasdirectoroftheinstituteofplantindustryfrom1916till1936.•  Died:26January1943,Saratov,Russia

Lawofhomologousseriesofvariation

•  LawofhomologousseriesofvariationisproposedbyVavilov.

•  Whichstatesthatcharactersfoundinonespeciesalsooccurinotherrelatedspecies.

•  Forexample,diploid(2X),triploid(3X)andhexaploid(6x)wheatsshowaseriesofidenticalcontrastingcharacters.

•  SimilarlygenusSecaleduplicatesthevariationfoundingenusTriticum.

•  Thusacharacterabsentinaspecies,bitfoundinarelatedspecies,islikelytobefoundinthecollectionsofthatspeciesmadefromthecentresoforigin.

•  EightmaincentresoforiginwereoriginallyproposedbyVavilovin1926.

•  Thesecentresare;1)China2)Hindustan3)CentralAsia4)AsiaMinor5)Mediterranean6)Abyssinia7)CentralAmerica8)SouthAmerica

Thechinacentreoforigin

•  Thisregionconsistsofthemountainousregionsofcentralandwesternchinaandtheneighbouringlowlands.

•  Atotalof138plantswerelisted.

Primarycentresoforiginfor;•  Glycinemax•  Raphanussativus•  Colocasiaantiquorum•  Panicummiliaceum•  Somespeciesofmillets•  Fagopyrumesculentum•  Papaversominiferum•  Secondarycentresoforiginfor;Zeamays,Phaseolusvulgaris,Vignaunguiculata,Sesamumindicum

•  Cammelliasinensis•  Avenanuda•  Brassica•  Allium•  Solanummelongena•  Prunusarmeniaca•  Citrus

TheHindustancentreoforigin•  Thiscentreincludes,

Burma,Assam,Malaya,Archipelago,Java,Borneo,SumetraandPhilippines9excludesnorthwestIndia,Punjab,andNorthwesternfrontierprovinces).

•  HindustancentreisdividedintoIndoBurmaandIndoMalayansubcentres

•  117specieswerelisted.

•  Primarycentresoforiginfor,•  Oryzasativa•  Cajanuscajan•  Cicerarietinum•  Vignaradiata•  Cucumissativus•  Lactucaindica•  Dioscorea•  Raphanusindicus•  Curcumadomestica

•  Saccharum•  Gossypium•  Cannabisindica•  Pipernigrum•  Indigofera•  Mangiferaindica•  Cocosnucifera•  Musasapientum

ThecentralAsiacentreoforigin•  IncludesnorthwestIndia(Punjab,Thenorthwest

frontierprovincesandKashmir),allofAfghanistan,ThesovietrepublicsofTadjikistanandUzbekistanandTian–shan.

•  ItalsoknownasAfghanistancentreoforigin.•  42specieswerelisted.

•  Primarycentresoforiginfor,•  Triticumaestivum•  T.compactum•  Pisumsativum•  Viciafaba•  Alliumsatium•  Pistachiavera

•  Secondarycentresoforiginfor,Secalecereale

•  Linumusitatissimum•  Carthamustinctorius•  Gossypium•  Cucurbitamoschata•  Daucuscarota•  Vitisvinifera

TheAsiaminorcentreoforigin•  ThisisalsoknownastheneareastorPersian

centreoforigin.•  ItincludestheinteriorofAsiaminor,thewholeTranscaucasia,IranandhighlandsofTurkmenistan.

•  83specieswerelisted.

•  Primarycentresoforiginfor,•  Triticum(9species)•  Medicagosativa•  Trifoliumresupinatum•  Brassicaoleracea•  Avenasativa•  Alliumsp.•  Secondarycentreoforiginfor,Brassicacampestris,B.nigra,B.japonica,B.rapa

•  Lactucasativa•  Ficuscarica•  Punicagranatum•  Malussylvestris•  Pyrussp.•  Prunus•  Vitisvinifera

TheMediterraneancentreoforigin•  Manyvaluablecerealsandlegumesareoriginatedfromhere.

•  84specieswerelisted

•  Primarycentreoforiginfor,•  Triticumdurum•  Triticumdicoccum•  Triticumsp.•  Avenasp.•  Hordeumvulgare•  Lensesculeta•  Mentasp.

•  Lathyrus•  Lupinussp.•  Trifoliumsp.•  Viciasativa•  Aspragusofficianalis•  Alliumsp.

TheAbyssiniancentreoforigin•  ItincludesEthiopiaandhillcountryofEritrea.•  38plantspecieswerelisted.

•  Primarycentreoforiginfor,•  Hordeumvulgare•  Triticumdurum•  T.turgidum•  T.dicoccum•  Sorghumbicolor•  Pennisetumglaucum•  Dolichoslablab•  Lathyrussativus•  Ricinuscommunis•  Coffeaarabica•  Allium•  Abelmoscusesculentus•  Secondarycentreoforiginfor,Victafaba

ThecentralAmericanorigin•  ThisincludestheregionofSouthMexicoandCentralamerica.

•  ItisalsoreferredastheMexicancentreoforigin.•  49speciesofplantswerelistedfromhere.

•  Primarycentresoforiginfor,•  Zeamays•  Phaseolusvulgaris•  P.lunatus•  Cucurbitamelanosperma•  Ipomeabatatus•  Cannaedulis•  Capsicumannum•  Gossypiumhirsutum•  G.purpureascens•  Caricapapaya•  Psidiumguajava•  Perseaamericana

ThesouthAmericancentreoforigin•  ThecentreincludeshighmountainregionsofPeru,Bolivia,Ecuador,ColumbiapartsofChileandBrazilandwholeofParaguay.

•  Chile-centreandBrazilian-Paraguaycentrearesubcentres

•  45plantswerelistedfromhere.

Centreofdiversity•  Plantsofaspecieslivingindifferentenvironmentarelikelytobedifferent.

•  Thusaplantspeciesarelikelytoshowconsiderablevariationinaregionwithvariedclimaticandotherecologicalconditions.

•  Areaswithmountainsandvalleysshowvariationinthepreleventenvironment.

•  So,plantspeciesalsoshowconsiderablevariationinthisarea.

•  Interestinglycentresoforiginaresituatedinmountain-valleyareas.

•  Thuscentresoforiginmaybemoreappropriatelycalledcentresofdiversity.

•  Zhukovskyin1965recognised12megagenecentresofcropplantdiversity.

•  IndiansubcontinenthavetwohotspotofbiodiversityintheeasternHimalayasandwesternGhats.

•  Atleast147agri-horticulturalcropspeciesarebelievedtobeoriginatedfromIndia.

Diversityinpotato

DiversityinTriticum

Diversityinzeamays

Sinskaya,1969

•  Scientistswhomadecontributionsoncentresofdiversity.

•  HestudiedonvariationinBarley.•  Afterheconcludedthat,overcentuariesandmilleniacultivatedbarleyhasadaptedtodifferentenvironmentalconditionsanddifferenthumanutilisationrequirements.

•  Thegenepoolofcultivatedbarleyhasthusaquiredaverylargemorphologicalandadaptivediversity.

Howcentresoforiginusefulinplantbreeding

•  Thestudyofcentersoforiginanddiversityishelpfulinplantbreedingandgeneticresearch.

•  Thegeneticvariationinthesecentersoftenservesasarichreserveofgeneticmaterialfortheimprovementofcultivatedcrops.

•  Genesfordisease,pestandstressresistance,andnutritionalqualityarejustsomeoftheresourcesthatcanbefoundinthesereserves.

•  Locatingtheoriginofcropplantsisbasictoplantbreeding.

•  Thisallowsonetolocatewildrelatives,relatedspecies,andnewgenes(especiallydominantgenes,whichmayprovideresistancetodiseases).

•  Knowledgeoftheoriginsofcropplantsisimportantinordertoavoidgeneticerosion,thelossofgermplasmduetothelossofecotypesandlandraces,lossofhabitat(suchasrainforests),andincreasedurbanization.

Conclusion

•  Recentcentreoforigindiscoveringstudiesarecontinuinganditismainlybasedonmoleculartechniques.

•  Eachandeveryagro-ecologicalgroupsarebasedonthestudyofhundredsorthousandsofaccessionsfromtheworldcollections.

•  Thustheseclassificationofcentresoforiginprovideorientationontheresourcesofaparticularcrop.

Reference•  Singh,B.D.Plantbreedingprinciplesandmethods.kalyani

publishers.2000•  Singh,J.&Dhillon,S.S.Agriculturalgeography.TataMcGraw-Hill

publishingcompanylimited.1984•  https://books.google.co.in/books?

id=JOcsswWOIscC&pg=PA66&lpg=PA66&dq=sinskaya+1969&source=bl&ots=FIdVKGMGq5&sig=VRzEtA_IB-iEWoZwnD-Pj3mOr7s&hl=en&sa=X&ved=0ahUKEwin5OeB9Y3WAhUCTbwKHdsyAnsQ6AEILjAD#v=onepage&q=sinskaya%201969&f=false

•  https://www.google.co.in/search?q=centre+of+origin&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj3sp6v9Y3WAhVEbrwKHegUA9MQ_AUICygC&biw=1366&bih=662