Fisiologia Vegetal.indb

Aula
HORMÔNIOS VEGETAIS
META
Estudar os efeitos dos hormônios vegetais nas plantas.
OBJETIVOS
$R¿QDOGHVWDDXODRDOXQRGHYHUi
HQWHQGHUDVIXQo}HVHHIHLWRVGRVKRUP{QLRVYHJHWDLVQDVSODQWDV
35e5(48,6,72
&RQKHFHUQRo}HVEiVLFDVGHFUHVFLPHQWRYHJHWDO
)RQWHKWWSZZZÁRUHVRQOLQHFRP
9
Fisiologia Vegetal
INTRODUÇÃO
+RUP{QLRV YHJHWDLV VmR FRPSRVWRV RUJkQLFRV QmR QXWULHQWHV SURGX]LGRVSRUSODQWDVJHUDOPHQWHHPXPORFDOGLIHUHQWHGDTXHOHRQGHVmR
XVDGRV7DLVKRUP{QLRVHPEDL[DVFRQFHQWUDo}HVUHJXODPRFUHVFLPHQWR
HDVUHDo}HVÀVLROyJLFDVGDVSODQWDV5HFHQWHPHQWHXPDJUDQGHTXDQWLGDGH
GHKRUP{QLRVYHJHWDLVIRLVLQWHWL]DGDHDOJXQVVmRXVDGRVFRPHUFLDOPHQWH
para matar ervas daninhas ou cultivar frutas.
$VSODQWDVVmRDOWDPHQWHRUJDQL]DGDVWDQWRHPWHUPRVGHIRUPDTXDQWR
GHIXQomR6mRRVKRUP{QLRVYHJHWDLVTXHFRRUGHQDPHLQWHJUDPRVSURFHVVRVGHFUHVFLPHQWRGDVSODQWDVHTXHSURYRFDPHVVHQtYHOGHRUJDQL]DomR
2 DVSHFWR GR FRQWUROH GR FUHVFLPHQWR GDV SODQWDV ÀFD SDUWLFXODUPHQWH
HYLGHQWHQRHVWXGRGHWHFLGRVYHJHWDLV3RUH[HPSORVHDVFpOXODVYLYDVTXH
QmRSHUGHUDPDFDSDFLGDGHGHVHGLYLGLUIRUHPUHPRYLGDVGHXPDSODQWDUHWRPDUmRRFUHVFLPHQWRDWLYRVHUHFHEHUHPQXWULHQWHVHVVHQFLDLVHKRUP{QLRV
GHFUHVFLPHQWR(QWUHWDQWRVHRHTXLOtEULRHQWUHRVGLIHUHQWHVKRUP{QLRV
QmRIRUH[WUHPDPHQWHSUHFLVRRUHVXOWDGRVHUiRFUHVFLPHQWRGHPDVVDV
WXPRUDLVGHFpOXODVYHJHWDLVTXHSDUHFHUmRWHUSHUGLGRFRPSOHWDPHQWHR
FRQWUROHGRVHXSRGHUGHRUJDQL]DomRHGHHVWUXWXUDomR3RURXWURODGR
DRDOWHUDURHTXLOtEULRHDFRQFHQWUDomRGHKRUP{QLRVGHSODQWDVQRPHLR
de cultura, os cientistas podem desenvolver plantas completas, com raiz
HFRSDHWRGDVDVVXDVFDUDFWHUtVWLFDVWtSLFDVDSDUWLUGHXPD~QLFDFpOXOD
0XLWDVGDVFKDPDGDV´SODQWDVGHSURYHWDµVmRSURGX]LGDVGHVVDIRUPD
$DomRKRUPRQDOHVWiGLUHWDPHQWHUHODFLRQDGDDRGHVHQYROYLmento dos vegetais (Fonte: http://www.brasilescola.com).
88
Hormônios vegetais
Aula
PRINCIPAIS CLASSES DE HORMÔNIOS VEGETAIS
9
2V KRUP{QLRV YHJHWDLV SRGHP VHU DJUXSDGRV HP GLYHUVDV FODVVHV
SULQFLSDLV (VVDV FODVVHV VmR GHWHUPLQDGDV SHODV FDUDFWHUtVWLFDV TXtPLFDV
GRVKRUP{QLRVRXSHORVHIHLWRVTXHH[HUFHPVREUHDVSODQWDV2VJUXSRV
RXFODVVHVGHKRUP{QLRVYHJHWDLVRXÀWRUP{QLRVVmRGLYLGLGRVHPFLQFR
$X[LQDV&LWRFLQLQDV*LEHUHOLQDV$FLGRDEVFtVLFR(WLOHQR
FITOHORMÔNIOS OU REGULADORES
DO CRESCIMENTO
)LJXUD([SHULrQFLDVTXHOHYDUDP
à descoberta dos hormônios vegetais
(Fonte: www.herbario.com.br).
AUXINAS
6mRRVFRPSRVWRVTXHSURYRFDPRDORQJDPHQWRQDVFpOXODVGRVEURWRV
GHSODQWDV$VDX[LQDVVmRVLQWHWL]DGDVHDSUHVHQWDPDVFRQFHQWUDo}HVPDLV
altas nas áreas meristemáticas do broto e da raiz, áreas nas quais as células
VHGLYLGHPUDSLGDPHQWHSDUDUHQRYDURVHXFUHVFLPHQWR$VDX[LQDVVmR
deslocadas por toda a planta a partir dessas áreas.
89
Fisiologia Vegetal
4XDQGR DSOLFDGD H[WHUQDPHQWHjV H[WUHPLGDGHVGH FDXOHVLQFLVRV D
DX[LQD HVWLPXOD VXD IRUPDomR (P GRVDJHQV H[FHVVLYDV SRUpP LQLEH D
IRUPDomRGHUDt]HV(PJHUDORWHFLGRGDUDL]pFRQVLGHUDYHOPHQWHPDLV
VHQVtYHOjDX[LQDGRTXHRWHFLGRGRFDXOH3RUWDQWRDVFRQFHQWUDo}HVGH
DX[LQDPDLVIDYRUiYHLVSDUDRDORQJDPHQWRGRFDXOHQRUPDOPHQWHUHVXOWDP
QDLQLELomRGRGHVHQYROYLPHQWRGDUDL]
(VVDVHQVLELOLGDGHGLIHUHQFLDGDID]FRPTXHDVH[WUHPLGDGHVGREURWRGDV
SODQWDVDSUHVHQWHPXPJHRWURSLVPRQHJDWLYRLVWRpÀTXHPYROWDGDVSDUDFLPD
TXDQGRFRORFDGDVHPSRVLomRKRUL]RQWDOQHVVDVPHVPDVFRQGLo}HVDVH[WUHPLGDGHV
GDUDL]DSUHVHQWDPXPJHRWURSLVPRSRVLWLYRRXVHMDÀFDPYROWDGDVSDUDEDL[R
SDUDGHQWURGRVROR4XDQGRDJUDYLGDGHID]FRPTXHDDX[LQDVHDFXPXOHQDSDUWH
LQIHULRUGRFDXOHDVFpOXODVPDLVEDL[DVVHDORQJDPPDLVGRTXHDVGHFLPDID]HQGR
FRPTXHDH[WUHPLGDGHTXHHVWiHPFUHVFLPHQWRVHYROWHSDUDFLPD1RFDVRGDUDL]
HQWUHWDQWRDVLWXDomRpLQYHUVD$FRQFHQWUDomRPDLRUGHDX[LQDQDSDUWHLQIHULRU
inibe o alongamento das células naquele local, e o alongamento relativamente
PDLRUGDVFpOXODVVXSHULRUHVID]FRPTXHDH[WUHPLGDGHGDUDL]VHYROWHSDUDEDL[R
EFEITOS DA AUXINA
$VDX[LQDVSRGHPSURGX]LUGLYHUVRVHIHLWRVLQWHUHVVDQWHVQRVYHJHWDLV
tais como:
VmR DWLYDV HP TXDQWLGDGHV PXLWR SHTXHQDV H TXDQGR DSOLFDGDV HP
TXDQWLGDGHVPXLWRHOHYDGDVSRGHPPDWDURYHJHWDO
FRPRVmRWUDQVSRUWDGDVGDFRSDSDUDDVEDVHDVDX[LQDVWHQGHPDVH
FRQFHQWUDUQDVUDt]HVRQGHVHDFXPXODPHPOLJHLURH[FHVVRHUHWDUGDPR
crescimento. No caule, ao contrário, sempre há menos hormônio do que
RLGHDOSDUDRFUHVFLPHQWReSRULVVRTXHXPOLJHLURDFUpVFLPRGHDX[LQD
UHWDUGDRFUHVFLPHQWRGDVUDt]HVHDFHOHUDRGRFDXOH
DVDX[LQDVSURGX]LGDVSHORyYXORIHFXQGDGRSURYRFDPDWUDQVIRUPDomR
GDVSDUHGHVGRRYiULRQRIUXWRÀJXUD
)LJXUD7UDQVIRUPDomRGDVSDUHGHVGRRYiULRQRIUXWR
SHODVDX[LQDVZZZFLDJULXVSEU
90
Hormônios vegetais
Aula
eSRULVVRTXHVHLPSHGLUPRVDIHFXQGDomRGRyYXORHDSOLFDUPRVXPD
SHTXHQDTXDQWLGDGHGHDX[LQDQDVSDUHGHVGRRYiULRREWHUHPRVIUXWRV
partenogenéticos, sem sementes.
DVDX[LQDVFRPRMiYLPRVSURYRFDPDVFXUYDWXUDVGRVYHJHWDLVFDXVDGDV
SHODJUDYLGDGHJHRWURSLVPRHSHODOX]IRWRWURSLVPR
RVEURWRVTXHÀFDPQDH[WUHPLGDGHVXSHULRUGRVFDXOHVHGRVUDPRV
SURGX]HPDX[LQDVTXHDRGHVFHUHPDRORQJRGRFDXOHLQLEHPRGHVHQvolvimento da maioria das gemas laterais(dominância apical), impedindo
TXHVHGHVHQYROYDPIRUPDQGRUDPRV
6HFRUWDUPRVREURWRWHUPLQDOGRFDXOHSDUDQGRGHGHVFHUDX[LQDRV
brotos laterais se desenvolvem formando novos ramos.
RVIUXWRVHDVIROKDVSRVVXHPDFDPDGDGHDEVFLVmRÀJXUDSHODTXDO
FDHP(VWDFDPDGDQmRVHIRUPDHQTXDQWRRIUXWRHDIROKDVmRYHUGHVHSURGX]HPDX[LQDV$RDPDGXUHFHUHPRVIUXWRVHDVIROKDV
DDX[LQDGHL[DGHVHUSURGX]LGDHDFDPDGDGHabscisão
se forma e provoca a sua queda.
HPGRVHVUHODWLYDPHQWHSHTXHQDVDVDX[LQDVSURYRFDP
o enraizamento de estacas, sendo, por isso, muito úteis na
UHSURGXomRDVVH[XDGDGRVYHJHWDLV
DVVRFLDGDV D RXWURV SURGXWRV DV DX[LQDV VmR
usadas na cultura de células e tecidos vegetais, fa]HQGR FRP TXH KDMD QmR DSHQDV GLYLVmR FHOXODU
FRPRGLIHUHQFLDomR(VWHSURFHVVRGHQRPLQDGRGH
´PLFURSURSDJDomRµSHUPLWHTXHVHIDoDDSDUWLUGH
DOJXPDVFpOXODVDFORQDJHPGHLQGLYtGXRV
AUXINAS E REGULADORES
DE CRESCIMENTO
9
$EVFLVmR
Refere-se à perda de uma parte
do corpo. É normalmente referido
para descrever o
processo através
do qual uma planta perde uma ou
mais partes da sua
estrutura: folha, semente, fruto.
)LJXUD &DPDGD GH $EVFLVmR
(Fonte: www.homestead.com).
2iFLGRLQGRODFpWLFRpDDX[LQDQDWXUDOTXHSURGX]LGDSHORYHJHWDO
FRQWURODPXLWRVGHVHXVSURFHVVRVPHWDEyOLFRV
([LVWHP RXWURV SURGXWRV FRPR RV iFLGRV QDIWDOHQRDFpWLFR LQGRO
EXWtULFRHLQGROSURSL{QLFRTXHWrPHIHLWRVVHPHOKDQWHVHTXHFRPRQmR
VmRQDWXUDOPHQWHSURGX]LGRVSHORVYHJHWDLVQmRGHYHPVHUFKDPDGRVGH
hormônios, mas de reguladores de crescimento.
GIBERELINA
$KLVWyULDLQLFLDOGDVJLEHUHOLQDVIRLXPSURGXWRH[FOXVLYRGRVFLHQWLVWDV
MDSRQHVHV(P(.XURVDZDHVWXGDYDXPDGRHQoDGHDUUR]2U\]DVDWLYDGHQRPLQDGDGHGRHQoDGDV´SODQWLQKDVORXFDVµQDTXDODSODQWDFUHVFLD
91
Fisiologia Vegetal
UDSLGDPHQWHHUDDOWDFRPFRORUDomRSiOLGDHDGRHQWDGDFRPWHQGrQFLDDFDLU
.XURVDZDGHVFREULXTXHDFDXVDGHWDOGRHQoDHUDXPDVXEVWkQFLDSURGX]LGD
SRUXPDHVSpFLHGHIXQJR*LEEHUHOODIXMLNXURLRTXDOSDUDVLWDYDDVSOkQWXODV
$JLEHUHOLQDIRLDVVLPGHQRPLQDGDHLVRODGDHP$VJLEHUHOLQDVHVWmR
presentes possivelmente em todas as plantas, por todas as suas partes e em
GLIHUHQWHVFRQFHQWUDo}HVVHQGRTXHDVPDLVDOWDVFRQFHQWUDo}HVHVWmRHP
VHPHQWHVDLQGDLPDWXUDV0DLVGHJLEHUHOLQDVMiIRUDPLVRODGDVHLGHQWLÀFDGDVTXLPLFDPHQWH2JUXSRPDLVEHPHVWXGDGRpR*$FRQKHFLGRSRU
DFLGRJLEHUpOLFRTXHpWDPEpPSURGX]LGRSHORIXQJR*LEEHUHOODIXMLNXURL
As giberelinas têm efeitos drásticos no alongamento dos caules e folhas
GHSODQWDVLQWDFWDVDWUDYpVGDHVWLPXODomRWDQWRGDGLYLVmRFHOXODUFRPR
do alongamento celular.
LOCAIS DE PRODUÇÃO DAS GIBERELINAS
NO VEGETAL
$VJLEHUHOLQDVVmRSURGX]LGDVHPWHFLGRVMRYHQVGRVLVWHPDFDXOLQDUHVHPHQWHVHPGHVHQYROYLPHQWReLQFHUWRVHVXDVtQWHVHRFRUUHWDPEpPQDVUDt]HV$SyV
DVtQWHVHDVJLEHUHOLQDVVmRSURYDYHOPHQWHWUDQVSRUWDGDVSHOR[LOHPDHÁRHPD
GIBERELINAS E OS MUTANTES ANÕES
$SOLFDQGRJLEHUHOLQDHPSODQWDVDQmVYHULÀFDVHTXHHODVVHWRUQDP
LQGLVWLQJXtYHLVGDVSODQWDVGHDOWXUDQRUPDOSODQWDVQmRPXWDQWHVLQGLFDQGRTXHDVSODQWDVDQmVPXWDQWHVVmRLQFDSD]HVGHVLQWHWL]DUJLEHUHOLQDV
e que o crescimento dos tecidos requer este regulador.
GIBERELINAS E AS SEMENTES
Em muitas espécies de plantas, incluindo o alface, o tabaco e a aveia
selvagem, as giberelinas quebram a dormência das sementes, promovendo
RFUHVFLPHQWRGRHPEULmRHDHPHUJrQFLDGDSOkQWXOD(VSHFLÀFDPHQWHDV
JLEHUHOLQDVHVWLPXODPRDORQJDPHQWRFHOXODUID]HQGRFRPTXHDUDGtFXOD
rompa o tegumento da semente.
GIBERELINAS E DESENVOLVIMENTO DE FRUTOS
*LEHUHOLQDVDVVLPFRPRDX[LQDVSRGHPFDXVDURGHVHQYROYLPHQWRGH
IUXWRVSDUWHQRFiUSLFRVVHPVHPHQWHVLQFOXLQGRPDomDEyERUDEHULQMHOD
HJURVHOKD$PDLRUDSOLFDomRFRPHUFLDOGDVJLEHUHOLQDVpQDSURGXomRGH
XYDVSDUDDPHVD2iFLGRJLEHUpOLFRSURPRYHDSURGXomRGHIUXWRVJUDQGHV
sem sementes, soltos entre si.
92
Hormônios vegetais
APLICAÇÕES PRÁTICAS DAS GIBERELINAS
*LEHUHOLQDVSRGHPVHUXVDGDVQDTXHEUDGHGRUPrQFLDGHVHPHQWHVGH
YiULDVHVSpFLHVGHYHJHWDLVDFHOHUDQGRDJHUPLQDomRXQLIRUPHGHSODQWDo}HV(P
VHPHQWHVGHFHYDGDHRXWUDVJUDPtQHDVDJLEHUHOLQDSURGX]LGDSHORHPEULmR
DFHOHUDDGLJHVWmRHPUHVHUYDVQXWULWLYDVFRQWLGDVQRHQGRVSHUPDUHJLmRULFD
HPUHVHUYDVSRLVHVWLPXODDSURGXomRGHHQ]LPDVKLGUROtWLFDV
*LEHUHOLQDV SRGHP VHU XVDGDV SDUD DQWHFLSDU D SURGXomR GH VHmentes em plantas bienais. Juntamente com as citocininas, desempenham
LPSRUWDQWHSDSHOQRSURFHVVRGHJHUPLQDomRGHVHPHQWHV
*LEHUHOLQDVHDX[LQDVVmRODUJDPHQWHXWLOL]DGDVSDUDDSURGXomRGH
IUXWRVSDUWHQRFiUSLFRVVHPVHPHQWHV*LEHUHOLQDVHVWLPXODPRÁRUHVFLPHQWRGHSODQWDVGHGLDORQJR3'/HELHQDLV
CITOQUININAS
Aula
9
6HQHVFrQFLD
É o processo de envelhecimento dos
seres vivos - quando as células deixam de se dividir
para substituírem
outras células que,
por alguma razão,
deixaram de metabolizar.
&LWRTXLQLQDVRXTXLQLQDVpJUXSRGHKRUP{QLRVTXHSURPRYHDGLYLVmRFHOXODUDRLQYpVGRDORQJDPHQWRFHOXODU$VFLWRTXLQLQDVVXUJHPQDV
UDt]HVGDVSODQWDVHVmRWUDQVSRUWDGDVSDUDFLPDDWpRVEURWRVeSRVVtYHO
que também se originem em algumas folhas e brotos jovens. A primeira
citoquinina a ser conhecida, a cinetina, foi isolada de um animal (do ADN
do sêmen do arenque). Mas outras têm ampla ocorrência em plantas e já
foram isoladas e caracterizadas quimicamente.
$VFLWRTXLQLQDVSDUHFHPVHUDVJUDQGHV´QRUPDWL]DGRUDVµGRFUHVFLPHQWR
de plantas. Têm um papel importante no desenvolvimento controlado e organizado da forma e da estrutura das plantas superiores. Quando adicionadas a
culturas assépticas nas concentrações adequadas, as citoquininas provocam a
GLIHUHQFLDomRGRVJUXSRVGHFpOXODVTXHIRUPDPRVWHFLGRVTXHHYHQWXDOPHQWH
VHWRUQDUmRDVGLIHUHQWHVSDUWHVGDVSODQWDV$GHVFREHUWDGHVVHIDWRQDGpFDGD
GHHVWDEHOHFHXRDUFDERXoRSDUDVXFHVVRVH[SHULPHQWDLVSRVWHULRUHV1R
LQtFLRGDGpFDGDGHMiVHFULDYDPSODQWDVLQWHLUDVVXVSHQVDVHPPHLRV
QXWULWLYRVDUWLÀFLDLVDSDUWLUGHFpOXODV~QLFDVHLQGLIHUHQFLDGDV
2XWUDIXQomRLPSRUWDQWHGDFLWRTXLQLQDpDLQLELomRGDsenescência, isto é,
GRHQYHOKHFLPHQWRSULQFLSDOPHQWHHPFXOWXUDVGHYHJHWDLVGHIROKDVYHUGHV2V
KRUP{QLRVDXPHQWDPDUHWHQomRGHDOJXPDVVXEVWkQFLDVWDLVFRPRDPLQRiFLGRVGHQWURGDFpOXOD&RQVHTXHQWHPHQWHWDLVVXEVWkQFLDVSRGHPUHWRUQDUDR
FLFORDWUDYpVGDVtQWHVHGHSURWHtQDVTXHVmRHVVHQFLDLVSDUDRFUHVFLPHQWR
HDUHSDUDomRGHWHFLGRV'HVVHPRGRRHQYHOKHFLPHQWRRDPDUHOHFLPHQWR
HDFRQVHTXHQWHSHUGDGHTXDOLGDGHPHUFDGROyJLFDGRVSURGXWRVFROKLGRV
é consideravelmente retardada. Uma citoquinina sintética, a benziladenina,
HVWiFRPHoDQGRDVHUXVDGDH[SHULPHQWDOPHQWHFRPRLQLELGRUGHVHQHVFrQFLDHPPXLWRVWLSRVGHSODQWDVYHUGHVWDLVFRPRDOIDFHEUyFROLVHDLSR
93
Fisiologia Vegetal
ETILENO
2HWLOHQRpRFRPSRVWRRUJkQLFRHQGyJHQRRXH[yJHQRPDLVVLPSOHV
HDSDUHQWHPHQWHR~QLFRJiVTXHSDUWLFLSDGHUHJXODomRGRVSURFHVVRV
ÀVLROyJLFRVGDVSODQWDV2HWLOHQRpFRQVLGHUDGRXPKRUP{QLRMiTXHp
XPSURGXWRQDWXUDOGRPHWDEROLVPRDWXDHPFRQFHQWUDo}HVPXLWREDL[DV
HSDUWLFLSDGDUHJXODomRGHSUDWLFDPHQWHWRGRVRVSURFHVVRVGHGHVHQYROvimento e crescimento das plantas.
A vantagem original do gás etileno como regulador do crescimento reside
QRIDWRGHTXHQmRH[LJHDWLYLGDGHPHWDEyOLFDSDUDVHXWUDQVSRUWHHHPFHUWRV
FDVRVSDUDVXDLQDWLYDomR$GLIXVmRGRJiVpVXÀFLHQWHSDUDVHXWUDQVSRUWHH
SDUDGLPLQXLUVXDFRQFHQWUDomR$PDLRUGLÀFXOGDGHGRVHVWXGRVFRPRJiV
etileno é que ele está geralmente presente na atmosfera, particularmente nas áreas
de atividade industrial ou de trânsito intenso. Além disso, praticamente todos
RVFRPSRVWRVRUJkQLFRVOLEHUDPHWLOHQRTXDQGRVmRDTXHFLGRVRXR[LGDGRV
Finalmente, as plantas sujeitas à vários tipos de estresse, como o ataque
GHLQVHWRVHPLFURUJDQLVPRVRFRQWDWRFRPVXEVWkQFLDVWy[LFDVDFRORFDomR
HPSRVLomRKRUL]RQWDODH[SRVLomRDEDL[DVWHPSHUDWXUDVHDSUHVHQoDGH
SRWHQFLDLVGHiJXDEDL[RVQRVWHFLGRVSURGX]HPHWLOHQRDFLPDGRVQtYHLV
esperados em plantas normais.
ÁCIDO ABSCÍSICO
1RVSHUtRGRVIDYRUiYHLVjYHJHWDomRDVJHPDVGDSODQWDÀFDPHPLQWHQVD
atividade, dividindo constantemente as suas células e promovendo o cresciPHQWRYHJHWDO1RVSHUtRGRVGHVIDYRUiYHLVDVJHPDVGHYHPSHUPDQHFHUHP
UHSRXVRHSURWHJLGDVSDUDQmRPRUUHU)RLREVHUYDGRTXHDQWHVGRSHUtRGR
GHVIDYRUiYHODSODQWDSURGX]KRUP{QLRiFLGRDEVFtVLFRTXHpUHVSRQViYHO
pela dormência das gemas do caule e pela queda das folhas.
2VHIHLWRVVmRIHFKDPHQWRGRVHVW{PDWRVLQGXomRGRWUDQVSRUWHGHIRWRVVLQWHWL]DGRVGDVIROKDVSDUDDVVHPHQWHVHPGHVHQYROYLPHQWRLQGXomRGDVtQWHVH
GHSURWHtQDVGHUHVHUYDHPVHPHQWHVHPEULRJrQHVHTXHSRGHDIHWDUDLQGXomRH
PDQXWHQomRGDGRUPrQFLDHPVHPHQWHVHJHPDVGHFHUWDVHVSpFLHV
CONCLUSÃO
3DUDÀQDOL]DUJRVWDUtDPRVTXHYRFrSHUFHEHVVHDLPSRUWkQFLDGRV
hormônios vegetais como reguladores do crescimento das plantas suSHULRUHV8PKRUP{QLRpXPDVXEVWkQFLDTXtPLFDSURGX]LGDHPFHUWRV
tecidos do organismo e transportada para outros tecidos onde provoca
XPDUHVSRVWDÀVLROyJLFD
94
Hormônios vegetais
2KRUP{QLRpXPDVXEVWkQFLDDWLYDHPTXDQWLGDGHH[WUHPDPHQWH
SHTXHQDSRULVVRpLPSRUWDQWHTXHYRFrVDLEDLGHQWLÀFDUDVVXDVIXQo}HV
e efeitos nas plantas.
1D DJULFXOWXUD D DX[LQD H JOLEHUHOLQD VmR SXOYHUL]DGDV QDV FXOWXUDV
(VVDVVXEVWkQFLDVSURYRFDPDÁRUDomRVLPXOWkQHDGHSODQWDo}HVGHDEDFD
[LHYLWDPDTXHGDSUHPDWXUDGHODUDQMDVHSHUPLWHPDIRUPDomRGHXYDV
sem sementes. Aumentam, ainda, o tempo de armazenamento de batatas,
impedindo o brotamento de suas gemas.
$ XWLOL]DomR GH KRUP{QLRV YHJHWDLV FRPR D ²' iFLGR GLFORUR
IHQR[LDFpWLFRXPDDX[LQDVLQWpWLFDTXHpXPKHUELFLGDVHOHWLYRpLQyFXD
SDUDJUDPtQHDVFRPRDUUR]WULJRFHQWHLRSRUpPPDWDHUYDVGDQLQKDVGH
IROKDVODUJDVFRPRFDUUDSLFKRVSLF}HVGHQWHVGHOHmR
Aula
9
RESUMO
Nesta aula você pode observar o efeito dos hormônios vegetais como
substâncias reguladoras do crescimento das plantas superiores.
2VKRUP{QLRVHPEDL[DVFRQFHQWUDo}HVUHJXODPRFUHVFLPHQ
WR H DV UHDo}HV ÀVLROyJLFDV GDV SODQWDV 5HFHQWHPHQWH XPD JUDQGH
TXDQWLGDGHGHKRUP{QLRVYHJHWDLVIRLVLQWHWL]DGDHDOJXQVVmRXVDGRV
comercialmente para matar ervas daninhas ou cultivar frutas. Podem
VHUDJUXSDGRVHPGLYHUVDVFODVVHVSULQFLSDLV(VVDVFODVVHVVmRGHWHU
PLQDGDVSHODVFDUDFWHUtVWLFDVTXtPLFDVGRVKRUP{QLRVRXSHORVHIHLWRV
TXH H[HUFHP VREUH DV SODQWDV 2V JUXSRV RX FODVVHV GH KRUP{QLRV
YHJHWDLVRXÀWRUP{QLRVVmRGLYLGLGRVHPFLQFR$X[LQDV&LWRFLQLQDV
*LEHUHOLQDV$FLGRDEVFtVLFR(WLOHQR
$VDX[LQDVVmRRVFRPSRVWRVTXHSURYRFDPRDORQJDPHQWRQDVFpOXODV
GRVEURWRVGHSODQWDV$VDX[LQDVVmRVLQWHWL]DGDVHDSUHVHQWDPDVFRQFHQWUD
ções mais altas nas áreas meristemáticas do broto e da raiz, áreas nas quais as
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As giberelinas têm efeitos drásticos no alongamento dos caules e
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para cima até os brotos.
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das plantas, participando de praticamente todos os processos de crescimento,
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das gemas do caule e pela queda das folhas.
95
Fisiologia Vegetal
ATIVIDADES
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herbario.com.br).
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da planta, provocando a sua curvatura.
3. A curvatura da planta ocorre porque o lado iluminado cresce mais do
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COMENTÁRIO SOBRES A ATIVIDADES
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de um organismo apropriado sob condições controladas.
PRÓXIMA AULA
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96
Hormônios vegetais
AUTOAVALIAÇÃO
Aula
9
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3. Quando se poda uma roseira, observa-se um rápido crescimento das
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as gemas laterais:
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e) forma uma nova gema apical em lugar da eliminada.
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destas camadas está relacionada, pelo menos em parte, com:
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REFERÊNCIAS
)(55(,5$/*5Fisiologia vegetal: 5HODo}HV+tGULFDV Fortaleza:
(GLo}HV8)&
+23.,16:*Introduction to plant physiologyHG1HZ<RUN
-RKQ:LOH\6RQV,QF
5$9(13+(9(575)(,&++2516(Biologia vegetal. 6 ed.
5LRGH-DQHLUR*XDQDEDUD.RRJDQ
7$,=/=(,*(5(Fisiologia vegetalHG(GLWRUD$UWPHG
97