Weed biology: importance to weed management

W'eedScìence,45:349 356. 1997
SlmPosium:ImPortanceof ueed bUlogy t0 ueed mãnag€ment
\l/eedScienceSocierlof America, Norfolh, Virginia, 1996
Weedbiology: importanceto weed management
Prasanta
C. Bhowmik
Dcpaíncr(
uf Pld rìd Soil S.ictrcci UniÌc.ritl
òf Masgchusets, Amhei*, Ì\4À 01003
Knowledge of {ed bioios/ is essendil for dseÌÒpment of borh €coronicãÌll ànd
cnviroDnent lly .cc€poblc weed man?gêmêntsysems. lic€ì biôÌÕ$' reììresrô l,Ì3nt
rtributcs such * Áorpholog,', seed dormmcy and gerninarion, phpiology of
growih, @nìpetirive abilitr, rnd reproductive biology. Concepts ofpopulãtion biol.nn'r- a' d oor r*en- J"r r"n.q and or
;s)
- .c.dtr \ dyrrrrig * i r"yr .hr ' g " o , ' " "p , o p " Ae. o "p J . r n , l . , n b e u e d t o t ' " d i, - . . J i , G i ' i ^ t u
n e " e r" n J r " e ' , l u _ c u ' , i n , b l " r n r n , g e m e n. rtn r e g r c .T , e g , r . " d' o p , u r h b h give p.ioritr to deplerion of reot rerrves or seedbrnis rlìrcugh inÈrfsing with
doimancy or sernÌinâtion reqúiremenrshave grcat potentiãÌ to úlDnce weed mxnrs€m€nt sÈtegies in the future.
Nomenclature Conmon hilkweed, Á.á?@ rye.z L. ASCSÍ purple nltsedgc,
C!?c/u ntanà,s L. C\PKO; ycllorv nursedge,Cyü^ 6tu1Ì"r* L. CvPEï v.1\.Í'
],àÍ, Ábunlofl thco?h6tì }l€dí s ABlrTH.
Key words: wed biology, weed managenent, popuÌaÌion biologr',ASCSX CWRO,
CYPES,ABUTH.
For cenruries, namLal vegetation has been changed by
g r o r i n g u , , o ' ì \ ì , t l r r ô Í r g r i , , , ì , , , r eC, , n t t , ' r d ' xr i ô n
p r . r i . c ' , u c h a . . u l , i \ J r ì o n .r ' e o t r e n l i z e r . i. n , r o d u . r i o n
of crops, use ofmonoculure, and ctensive use ofpesticides
h J v e r f f e . . c d , g r i . u ì r u r u ì e c o . y s t e m .\.f e e d r p e . , e ' i r c p i
oneers thât increaxe diversiry of agricuhumÌ ecosystems by
usilg rheir envirormentaÌ potential. The divcmity is graduaìly increred by cropping systems targeted towards mximizing crop production. k is time for us to Ìook ìnto a31r i . u h u u l e . o . y . r e m ' r o m n i m , r p - o d u .r i o n i - p u , ' .
Considcrable literature is amìlable on weed biolog/, including úe characteristics, phenoÌogy, and life cycÌes of
many spccìcs.This pap* summarizessome of the literaturc
on úe biology of annuJ and perennial weeds with speciaÌ
referena to cornrnon rnillweed and nuaedges. k will high'
light some ìmporant attributes of weed biologl as they rerate to weed marÌâgement systems,
HistoricalPerspectives
ì
Studiesof weed biology stated as early as the 1930s.
(1937)perÍormeda seriesofquantitatìvesudPavÌychenko
ìes on rhe rooting characteristÌcsof weedsand crops grown
in comperitiveand noncompetitive
associations.
Thoscearly
studies demonstrated the imporrance of weed<rop interactionsin reladonto rhe root systemof weedsd1d cÌops.
In the northeast,â seriesof publicâtìonson the life history of soeral weed specics,including nuaedgc,was publishedin the 1960s(Bell et aÌ. 1962).The publicationof r
seriesof weedspecies
in "The BiologyofCanadianVeedí'
was
aúcn,pr o jnLily thc nnportanccof wcc<lL'iolosy
in weedsciencein the early1970s.This seriesincludednore
-er;ew'.in
rhan I00.pecie'*iú compr.h.n'i'. literarure
(Bhowmik
cluding common milkweed
anclBârÌdeen1976)
ud yellow nutsedge(Mull;gao md Junkins i976). IrÌ the
I980s, púbìicâtiônof "Ihe Biolosr of ÂustralianVeeds"
resulred ìn thorough Ìiterature reviews wÌtlì emphdis on
ecologicaìaspects.
rn spite of all the litcratuLeavailable,researchon wced biology and its potential usesin weed mãn
€ement sysrcmshas been limited.
roiew of Leferences
to weeds,AberIn a comprchcnsivc
nathy and Br;dscs(1996) indicatcdthar weedbiology/ecoÌof
ogy hrs conrinuerlro increse in termsofthe percentage
in th€ pre'1970s
total publicationsper decadefrom 14.3%0
ro l8.8ooi" rhe 9o0'. Tn ,orrrra.r.rhc per,ep.ionconcerningthe inìporlanceof weed bioÌogy to weed managcment h€Ìdby weedscientists
is slighdydifferenr,asindicãted
by úe surveyof Norris (1997). This suwey said the importanceof weed biologywas moderate(3.1 on a scaleol
5.0).
Earlier research included weed phenolosy, weed<rop
competition,ând repÌoductivebiology.DeveÌopment
of economic úresholds lor weedspecieshasmadesignificant progress in ihe lait d€càde. lntegrâted weed managementhas
focused on the effects of crop planting dates,row spacing,
cuÌtivators, ure of cover crops, ând reduced herbicide râtes.
Culent studies of weed biolosr are in nansition, Ìargely
due to the efTectsof agLìcuituLalpractices on weeds,cLop'
ping systems,and thc cnvironmenr.The reseuchemphasis
has changcdba;ed on the need to undersnnd basicweed
populabiology.ft is our job ro predicthow weedspecies,
tions, aÌÌd biorypesevolvein response
to selecrionpressufe
pLimarily due to agricuìtuLa1pLacrices.This klowledge wìll
hclp dwclop vccd managcmcntpracticcs.Curcnt rcscarch
in weedbiologr continuesto exploreweedseedbank
dynrmics, root Ìeserves,
tuber dormancy,evoÌurioDof weeds,úd
modclingof weedseedlinseneÌsence.
BhowmikWeedbiology:irìporrancc
to wcednÌãnâgenet .
349
encesin two yeÌlow nutsedgevarieties, C. escabnta.s
L. var.
$&h,t'!
L. aná C. esc*lznt* L. et lz?Ìo'tãcb]ú' Roe.A.
Cornrnon Milkweed
They found that .ar. escubntu:had longcr, narrorver, and
Common milkweed,a perennialweed nâdvero eâstern ro,c uprighrh"'e. ano Êewer
ruber..rLizorer.r.d,eed
headsrh-n 'ar. bpton,\u, rhey rì,o rrporcd ditÌcrenLial
Norrh America is limired to the regionboundedby 35 and
r0 degree"
N Lrirude.rndo0 and t0J dcgrees
ro severaÌherbic,des.
W longj,ud( suscepribiÌiry
(Bhowmik199-l).
In a comprehensive
studn differcnces
in growú ofpurpÌe
Comnon niÌkveed sedlings becoÌne perennial wnhin
nutsedge
from tubersreceived
lrom 14 stateswirhin rheU.S.
18 ro 21 d atìergeÍminâtioDb€causc
planrsbecomecapabÌe and from 21 locations around the world were noted fVills
ofproducingnevÌshootsfrcm buds(Biowmik 1993rBiow1978). Ditrerencesoccurredin the numbeLof shoos prornik and Bmdeen 1976; Evettsând Bumside 1972). The
duced from singÌe tubers, the number of leavesper shoot,
parent root survivesfor
and the lengrh and width of leaves.Differelces were also
growingseasons,
depenclingon soiÌ condirionsand ftequencyof rÍhge.
iounJ among,hr c.oDp.sfnr Roqe,,ng.lengrlrol rhe ra
.his Jnd rhenumber.ÌeneÌh.andw,d,hof i"volu.rallele,
PhenoÌogicaÌgrowth stase of cach speciesdescribesits
growth and subsequenrresponseto environmertal condi
ât the âpexofrhe rachis.Flowerpnrts,includingrhe number
tions, incÌuding growing degreedays. Common milkweed
ãnd lengú of seed staÌLsand the lengrh ol seedspikelets,
undergos nine phenologiol stagesto completeirs life cycle vried rmong ecotypes.Ìn general,greatervaÍetronswere
(Sinard et aÌ. 1988).Thesesascsincludcshootcncrgcncc, found mong thc plants from diFerent Ìocationsoutsidc dr
'<gerrrivc
srowh. bud{:se. umbel.honing.Íìsr Íloucnng. contìnenuÌ U.S. than from diflerent locationswithin the
ÍulÌ bÌoom.Ílowo *n-..n.e. 'malì ,cedpod. mrrure.ee,J
pod, and ripe seedpod. Simardet aÌ. (1988)idendlìcdrhese
phenological growth stagesand establishedrhe required de,
Population Biology
gree days lor each stage.The degreedays for each pheno,
logical growth stagecouÌd be ìmportant in predicring seasonal developmentof this specics.Thus, a degreeday rnodeÌ ,4..Annua.ts
bxed on phenologicalstagesof perenniaÌweedscould be
deveÌopedmd couÌd be usedin makingwcedmanagement
decisionsfocu.singon culural practices.The model could
Annual weed speciesreprodue by seedsand spread
alsobe usedto predicttiming ofchemicalconrrolpracrices.
through
dnpcrsalofsecds.The imponanceofshort distance
AeriaÌ shoots emergein spring (&ÌiÌ ro May) frcm uDweed
spread
in and bemeenarablefieldsha; beendescribed
dergtound adventirious root buds. Adventitious root buds
in
this
symposium
by ThilÌ et aÌ. (1997). They explained
arise eiúer on the stem base neâr the soil suface or on
some
causes
of
sprcad
and subsequent
elfectson crop prolareralroom (Bhowmikand Bandeen1976).
en rhereis
ductìon.
They
indicated
that
specÌÊc
weed
muagement opsufficicnr foliagc, root dwclopmcnt bccomcs activc. Root
growth terrninates during mid-Augüst to mid-September tions can be used to reduce nan-câused lveed seedspÌeed
and betweennearby6elds.Jordm (1992)emphcized
whcn most shootssenesce.
Most .oor buds remainviable within
q< krou ,oo Ìinle abou, unpre.li.r"ble
q,ia,ion. in
rhrr
throughoutthe severewinter months and sprout with the
seedd;spersalto do more rhm speculareabour the conrriadvent of spring.
FÌoweringoccun in lateJuneor earlyAugustdepending bution ol suchvariationsto weed managernenrThercforc,
the factorsúat controlseeddispeÌsâl,seedpÌoduction,and
on initiâÌ emergenc€and grorvth, weather conditions, and
seedsurvivaÌ may inÍìuence úe weed populatron.
habitaa. Plan* grown fron seedsseÌdom lìower until úeir
secondsummer (Bhowmik 1970; Bhowmik and Bandeen
1976). Àlso, newÌy d*eloped shootsfrom the sameroot
.y.rem normrily flo$er durtnCrhe ne\Í grôwing,caon.
to
Seedpods matureand spÌit open in eârÌyfâll (September
T\e pre"en.eo' J \ rop cúop) cu .hag. rhe.omperi.
October) and úe seedsare dispersedby wind, carricdby
growth and detive abiliry of weedspeciesand subsequent
the tufts of floss. Mature pods are found artached to dead velopment of weed species.Also, it can reduce production
stalks unril late fall (November to December) md wen the
of seeds.The presenceof corn (Zca nals L.) reducedseedfollowing spring.
rain ofvelvedeaf50%. This seed'raintcachedits maximum
Ìev€Ìat 20 to 30 plantsm '?in corn, and at 30 to 35 plânts
m'? in velvcdeafmonocuÌture(Zanin ând Sattin 1988).
Ecotypes
However, wiú only 4 to 5 plants m 2, velvedeafproduced
Nutsedge
8,000 ro 10,000seedsm 'zin competitionwirh corn.
Âccording to Grirneì model, velvcdeaf can be cÌasified
speciesdiversit/ has beendevelopedstodily under dispc.ics(Grihc 1177).Its bioÌosicâl
conditions. asa competitive+uderal
versecroppingslstemsandvariedenvironmenlaÌ
m.ke i. prnì.uJarìy
competi
rn,J
..olog.rl
chrrrcrcrlri.,
h.r'e
Ecorypi.rnìarion.r-"ng purprernd 'eììou nut'edge
I
rt
p
c
n
r
r
c
n
;
r
n
,
u
l
r
i
r
a
r
e
Ê
J
e
l
d
.
.
h
c
c
c
o
n
o
mti \rr e . h
r
i
r
c
a
n
d
becn r.porred o'ra and Appìeb1l9-6r Hruser Irú8:
plants
bâsis,
varies
between
0.3
and
1.7
old,
on
a
sìngle'year
1974).
The
vaLiations
have
been
identiStollerand Weber
'
m tZ;nin rnd 5J|lr- ìq88). Ba'edon rhe competi"rc
Íìed by name or physìcalcharacteristics.
abiÌity during úe vegetativephae ofvelvetleal the concept
YclÌow nutsedg. pl.nts froo Ceorgia grew mller, flowered
of growing degreedayscould be used to predict height, leal
larer, and produced larger tubers than plan$ from Delawire
(Hauser1968).Cosraand Àppleby (1976)describeddifferarea,and overalÌ production of biooass.
Phenology
u.s.
350 .
45, Mây-Jüne1997
WeedScience
Seedbanl Dynarnics
in anble
The vrst malorityofscedsenternrgrheseedbank
(Hune
Ar.hiháÌd
1986r
and
-eeds
l"nd co-. f'"n
""".,1
RobertsI9sl). Only 47o of the weedspeciesin arableland
aredescribedasperénnial(KÌopac196ô rimited dataexist
on rln r"r"l i'rpuror rll 'ccdr l,ro rnble ""iÌ Dìfferenrral
dare'^l lp.nine heNe(nând$irh'r .P(:es'\rcvcn' lr).ì')
upi.l <eic oiripe 'eed' and dlruge ro rìperrrrg'eeds
' i Ê ì c u l \r ,' ' e '
h a ' . m a d c' u c h ' . u d r c d
dur'ne,oll(.uon
rhelesi.Chancellor(in RobeÌts1970)estim.tteddìat a dense
stmd of weedsproducedmore than 1,235,000seedsm 'z.
ifhc posidonof-weedseedsin soil is likeìyto influencetheir
o o o u : r r u nd y n : - i . ' . | \ e ' p e c i e . . n m p u . i r iror r 'dr J c n ' i r y
;, *...1 '..J i" .oilq Ë.e,(,rl) bu' ''.lo*1, inled .
rl-. pr:nrary,oune of newiire"rari"n.ol "nnu,l *te.l' ea.h
1e.ri,no i.p'e'en'r rhc nr,oriq of "ccd .p<.ie' íelc
ì'r8JJ.\ecd;anl dynami..Íìu',u:rewdcly depcndìg on
rnd ìo*es(Burt
rhc m"enirudcor ncu 'eedirrrrodu.rions
sicleet d. l9s6j Wìbon 1988).The forrnationofseedbanks
of annual weed speciesand úe effccrs of selectedmanagement
pllctic€s
on those weed seedbank
were reviewed
jr
derailby Buhlerct al. (1997).
L a . r c r u o o n e . v v . mh c ' i r . o w n p r r t u l a r a " ' o cl i o n
s i r h w e d . ; - i e i . u . h r " r * d ' : n ì o u b u r hl i u c b e r rrl l a ,
ciniun anguxi:fol'an À1r.) (Yarbotough 3nd Bhowmik
1989), rca lCanellìa sínazos(L.) Kuntzel, sugar beet (Baz
wlgaris L.) , and soybeanlc\cine n,Lt (r.) Metr.) (Horzner
in a croppingsystemaJeâlsorep1982).Most veed specìes
resentedin the sccdbanL.Robens(1981) noted úac some
ol the greatestdiflerences;n weed floras are bctween ctops
in the lall and winter (i.e, winter
that haveweedseedÌings
appcaringìn thc
ceLeal)and cropsthar iiaveweedseedlnrgs
(e.g.,
coLn,
soybean,
and
springcetcals)
springúd Nrnmer
\eedbi-k' .J,/ fiom cÍoppi g 'y.rem ro croppinb'n'
rcm. Avenee total sccdbankdensitiesof aDnuâl weeds
rangedf."- 6OOto 162,000viableseedsrn 'zamongwiouslocationsin rhe Corn BeÌr(Forcellaet ai. 1992).Percent
ofviable scedthat emergedu seedlilgsin fieÌd pÌotsranged
fron lcs than tvo for ycÌlow Íó.k t (&arbarcd Mlsàf* R
Br.7ro rnoofo slat toxrail(narìa [ab".lHerrm.ì. Fedroor
p'e*eeJ rr'ryaunrtts ra,oflau L.t and common ìrmb'
qÁ,r. 1chül1od,unntbuq l.t tac,he rort fr"qJ.nrl)
encounteredspeìies.This study also indicat€d thât lìom t0
werenonviablc.Àgain,
ro 907ooftotal seedil rhe seedbaok
rhis nìformadon on weed speciesnumber, mortâlity, emerg.nce,rnd orh.. p-""*tere couÌd be ued in biocconomic
weed managemcntmodels.
moreproductiveon fcnile soils,addVeeds m geneLally
ing morc seedsto the seedbanki for *amplc Anaranthu
pouquií S.Wars ard Amaranthus retroflexrr L. respondedto
increascd soil fertiÌity with increasedsccd production
rHauprli
lr)-8ì. f'rr mlurc. 'pread* 'enrliz,r
"nd Jai"
c,n be rn imp"n,n, ,",r," of.""d, .ô, rhê ,""dh)nt o'
anble soils.Seedsof many weedspe.iescàn piss through
the digestive tracrs of cattle, shcep, horses,pigs, and goats
to be depositedin a viable state in the feces(Dore and
Râymond 1942; SalisburyÌ964). The seedbankof Clszapodiun 'pp. wu ,ignifrcJn,h highcÌ,inJ held re.eiv,ngm.
neignborinB
6cld rc'
rhan r a .omparablc
ceivingnone (BenÒit1986).
oí q.e'ì
lilìaeeere.'.r infl:"".4 rhero ì, rl di.rr:l-rrrion
'o
.-d i"ìh;'o'1. Ch,"ge. in reed 'eeddcp h in I ph' a
role in weed speciesshifts ãs dllxge Prãcticesâre altered
(BuhÌcr 1995rBúÌer et al. 1997).ln a srudyin MassacnuCronq ) planrsProduced
sens,horscweed(Cazlza .zurl'r'l
asmrny d 200,000secdsplart ' iI a no-tillagesitc (Bhow
mik and Bekech1993).The soil from the norillage sitehad
seedsof the toÉl seedsin the
80% eerminablehorseweed
r"p 2-.m. Th, ,,urnb.rot 'ecdslound oecli-.d ^ deprh
inir*'ed. \" germinrblered. *ere rourd below6.r ar
the norillage site. ln contrast,the converÌtionaltillagesite
had feweLhorsewecdreds than the no-tilÌage site. How*er,
througlÌoutthe surfacc14
the seedswere cvenly<listLibuLed
cm of soil in the conventionalsite. In a pasture,ForceÌla
and GllÌ (1986) showeddrat annualtiming of cultiration
such
composition.Species
had a dramaticeffecton species
as reá 6rcrc (Rronw ruben L.) and'si:l:vetgnss
lvulpìa bro'
(L.) s. F. Grayl arained dorninancein sunmer- and
moìì.es
early fall-tilled plots, whilc red sorrel ( Rand a&tosela L)
aul prustraLekno*ccd (?olxgotun d"nakft \") vcÍc s;s
nificanronly ìn plots cukiated in winter.
Spàtiâl distribution of weedsis importdt in alÌ irÌterâcplanrsard betwccnplaritsand rheir environrio"i
The lmportanceof spatiâldistributionof weedsúd
mcnt."-one
how spatial dhtribution influencespopulation and communiry dynmics has been presenredin lhis synPosium
(cardnìa r997).
d)"mi6
frrn,:ng pra.rite.inÊuen.cwccd puPuìa,,on
.pec.' .
o1,íIe.ring rhequ,,,"'i' t oÍ'eeJ'
"mpo'irion
"nd
returnedto md removedfrom soil (wiÌson l98B). Culti'
vatior playsa Ìnâjor role ìn depÌetiDgweedpopulationsin
of inpur from seedproduction,
arableland. In the absence
dre seedbankdeclinesmore rapi<ìlywirh cultÌvadonthan
without it (BhowmikaDdBclcch 1993;BridgesandlX'àÌker
1985; Brrhler 1995; Robens 1966). In England,seedling
on undisturbedsoil deplctedonÌy 17oof rìrcviemergence
abÌeieedbanL (Froud-wiÌliams .l tcs3; Robertsand
"ì
Dawk;ns 1967).
The use of herbicidesro complementstandardcultirztion
pracdca ca drroticalÌyreduceweedpopulatiotx itt soiÌ (Rob
efts and Ncilson 1981). For *amplc, anzinc t6-úloro-,4/usedin
erhyll/-(ì-methylethyl)-1,3,t-triaziDe-2,4-disminel
corn monocuhure reduced thc sccdbark 9870 úer 6 )Í
(Schweizerand Zmdúl 1984). How*et, 3 yr atter ârrzine
yr, rhe sccd'
w had been disconúnucdin pÌors neatedfor 3'Ihe
dynmia
to
ha1f
ns
orìgÌnal
deruirÍ
ban-khad reboundcd
;n a givcn field changeunder any integated wced
of seedbanks
mènascmcntsFtcm. Thc úangcs mut bc rccosniz€ddd
have to be inregued as m inpur ofweed demognphy
B, PeÍenniâls
Many weedspossess
an abiliry to colonìzereadiÌyin a
wide r.mge of disturbed habitats. Vegctativereproducdon is
'l'here
a common trait of perennialweeds.
in
exmpÌes of perenni:Ìweedsthat propagatevegetatively
one or more wâys. Vegetâtivepropâgârion Dìâyitrclude stolons,rhi'zones,rubers,bulbs,corms,room,and rems. Common rnlll:weed and both nutsedgesproduce seedsand vegetativcpropãgulesthat hãve €normouspotentiaÌfor coÌoniatìon and reproducdon.
Bhowmik\veedb;ology:importmc to weednanagement'
351
Root Bud Dgramics
of Common Millqreed
,io,rÕuìd be,,rÍg(,(Ì J
n,à, weeot. dro$|
t
.,h.
po.r-Roue,inb
{Jge or pe,(n-
common mìtÌ,wrcd
propâgJ
r vc8.,Jr\et) b\ a crccpinS
-oô'
)\(m. .rndrce roor,u{rrll) g oh ro r dppr\ ut ìoLr
Àhhough extensiveroor growrh occursduring thc firstru ì20 ,m íBhúsmika d tsrnJren o-r,t. Numcrnu.rdyea,grumh oi.ormon m:tlvcpd \hoo,\ io,n ì e âd"envdrririousroot budsappeardúouslÌourrhe roo! sl$rern,rhe
ririou' -oor butl, d" no. cìe,ge ||ú- 'o I un,il ,h(,e.ond
najority remainìngdormant (Bhowrnik Ì993; Bhownik
y€ (Bhowmik and Bandeen1976). The growth of roor
ând Bãndeer1976; Gcrlardt 1929;Groh 1943) until conbuds is smonglyinhibited by the parent stioot (Bhowmik
ditions favor dreir grorvth.
and Bândeen1976i Evett! dìd BurnsideÌ972; Jefïeryald
SeedÌingsproducebuds on rhe main roor closeto tlÌe
Robinson 1971), but rhc mechanismof nrhibitìon is un,
ground surfi.e wirhin r petiod of 18 to 21 d alìer emer- knowo. Apical dominance,hormonal
conrrol,and Ìoor regence(Bhowmik and Bandeen1976). In a clipping stLrdy servescould be responsibÌefor adventitious
rcot bud doru f . o q o n m i l k u c . J. e , d l i n s .,.h e . p - , r
;"
(Bhowmik
nancy
and
Bandeen
1976;
Everrs
and Burnside
tj,ri,iD
. rúed JnJ ,hc nu,',ì'e.of.lr). 'cqu:,edlo," .pfou,
nBde.
1973).
. , < r . F dr , d a ) . r , ú mp ì r n ,n b , o . t i i p i n s i ' , . * ; t e d' B I o * In general,roor bud clormancyin cornnon millveed
'o
mik arìd tsdnJ(er 6: tverr. md Burn,ideto 2r. Rc
increased
a the tot:ì sugarleveÌin roosrocl<sincreâsedin
moval of top gfowth lroD 2l-d-old seedlingsresultedin
rheirJlíBh"wm'k o-0r. Roo,hud.oloo, irgmcrrr.were
28oloresprouringof roor buds (EvcÍs and Burnside1972). Ìea.srdormant irÌ MaÍ An
averageof 13.2ok ol íoot frígThc 'uru'rJ and rrgrumlrof,eedlìn9:n.rcnedas.eedl:ng, ments wirh a visible bud remain-ed
dormant in May coni
de'(1"trd âddj'onrl leat pn-. rhi -umb.' or ,p'nu'ú
parcdro 52.2oloin Seprember
(Bhowmik Ì970). High renÈ
buds ianged from 5 ú i00o/o when tlìc seedlinls were
peraturebrokc root bud dormancy.\7hen incubatedat 27
clipp.,Ì d"*" !o 2 ro 3 cm comparedro 7.t ro I2.o cm
C, 80 to 95olo of roor lngments colÌected lrom May to
raÌl (Bhowmik ancl Bandcen1976). Thus, sprouringdoes AugLrsr
'proured.u 1,,1,
n,ìlyu-oo roor
-)oo
n o ro . . u r i r h c e d l i r r ug n' ' ì r h e ). , , e . l . p p . d . ; n J ì . a r ; n g , h ae,d q h ( n , o U c . r c di r r < " t ' r e m b c"f
Ar r. l 1 ( 2 s r o
oT
api.J .lom nân.c doer pìa1r ,uìr. AÍer . yr of nrurrJ
Ìoot fragmenrscollectedfrom May ro July sprouted.Howiund:,'u,bed)e.rrbli.hmcr. one .etJling produ.ed str
ever, rherewas no sprouring acrivity in Augusr and Seprcm
; r l l . ' . g e ' . ' , , c 1. ' n d0 4 ' " Ê , l l i n tis_. r I r - : r e r .
L,eraL 15 C.
Root Íìagrnents in rclarion to size, length, and maturiry
alsoplay an important roÌe in sprouringactiviryin relation
to the time neededfor sprouting.Smaìlerroot fLagrnents Tuber Dynamics of Nutsedges
reqüircda longerrilÌe for spÌouring(Minshall1977).Ninethber funanìcs
ry to 10070of root fragmenrs30 ro 45 cm in tengrhsprour
BõaÌ buÌbs úd tubersfunction borh s srorageand r<,
eJ. bur ,Ì.orreloor frâgmen''l'a'lcJ.o
well rcer-.5
productive
organsfor nursedge(Horowitz 1992).They d;Ê
"p-ou'
h'rdr lo2i)ì Onil 360ooi rl,c roor ir,rgmenr. .m in
prirnariÌy
fèr
by their posìrioDin relation to the rnother
Ìfnslh fon,,ed,\ous -e&hìngr" or s-owrrgrboverhe,urpÌant.
BasaÌ
bulbs
arc direcrlyconnectedto an aerialshoor.
Í r c e o í r h e g r o u nìJ - ú J i , c r p l J n ,n s { M i n s h J ìl lt , .
As rhizomes clongare, tubers are produad on rhizomes.
They consistof rhizomatoustissuewirh numeroushúds
(ViÌls 1987;\íills and Briscoe1973).Thesebudshaverhe
potenriaÌ to sprout and initiate rhimmatom growth rhar de
The roor rcscrves
ofcommon milkve€denablelons'term
velopsinto seedlings
and cvenually,maturepÌants.
survivaÌand vary overrhe gÌowhg scason(Bhowmik1993).
The percnt total cabohydnre of rooa (sampÌedto a depth
TuberInítìarkn and Farnation
of r n) of 6c1d-growncomoon milkwccd d..tincd fam
Ìate May to June,with a shup decline to about I 07o in JuÌy,
Undersuitablegrowingcondidons,a shootemerges
from
ud jncrearedto â plât€âu (25olo)in octobcr (Bhownik
a ruber 4 to 7 d after planting. Tuber formation beginsfrom
r970).
4 to 6 wk after seedlingemeLgence.
Usually, more rhan 95olo
The disribution of totaÌ sugârsvâri€d betweenplâDr of purple ald ycllow nutscdgeubers are lormed in the uppârts.The total sugarconrcntiD the stcm bse repÍesenred per 45 cm oí soil (Belìet al. 1962:Tripathì 1969).In gen17.4 to 23.2o/oof the toral dry weighr of this plant pan
er3Ì,more than 80o/ooftubers occurin úe uppeL15 cm of
(Bhowmik 1970). Sugrs peüed in the stem basein July, soil. Rhircmes,in generaì,do nor penerraredeeplyin heary
foÌÌowed by a sÌight reduction in Àugusr and September.
The total reducingsugn (total glucoseand fructose)in
The tuber productionofnutsedgeis remuLable,and the
Ìootstocks of commorÌ rniÌkweed Lemainedfa;rly omtant
crrcrr of,uber forma,i"nin J 8i\c,,s(r"oni. \(ry (\rcnrirc
(Bhardwaj and Vermâ 1968; Hâoser 1962i HoÍowitz 1972.
throughoutrhe growingseasonand rangedbetween0.48 to
2.2o/oof the total dry weight (Bhowmik 1970).The non
plant produced
Smirhdd Fick 1937).One yellownutsedge
reducingsugãr(sucrose)
conüibuteda mâjorponion of rotal
i,900 shootsând 7,000 tubers in 1yr (TumbÌesonand
susarsin common miÌkweedroo*tock (Bhowmik 1970). KonmedahÌ 1961). Under similar conditìons,fcwer and
The seasonalvariarions in roor resenesclearly demonsrrare smallertubersareproducedby yellowthanpurplenutsedge.
úe sourcc+ini!rlationsLip in coomon oilkwccd. Thc conHaNc (1962) found thar puryÌc truscfue plnlts fLom tuceprofsource-sinkrelationshipcould be ued to designsys- bers planted 90 cm apart overÌappeclin 5 wL. Áfter 20 wk
rcoic heLbicidesfor perennial weed control. ï hen eppficaof growth, approximately5,700 km ha Ì of rhi.zoneshad
352 .
WecdScience
45, May Jure 1997
becr produred.Bó<J o" our !udi" ì" Mo':.hu crs yeÌ
pr"du.eds -any a. l0 'o l< rnìllionruber"
low
' r Inur'edge
t u p f c r. c L m . o i ) i n d g r o w ; n g . e à ' o n .
VarioJs lactors influence überi'zâtioD of nutscdgesPecies.
Tub€riation ìs the result of a responseof mrrsedgeplants
regula.ed
br gror.rh'ub'rrn.e" and
rn eqe+,:.hohytlra-e.
of Dho,ôpirioJrnd rcnrpera'urcluberÍor
ro inLera.rionr
shon
m.rion,n velow nu'.edgeit inflrrened L1 da1rerrgrh.
phororyrioJ'rimulrreJ reprodu.ri..gromh rtsel'ct 'ì
ì962:lans! 1971).Iì}ìizonesdiffcrcntiatcinto tubersr*h
uÉo ro
'h"n hulb' in pLnr. gruwnwirl, , phoropcrioJ
"'| ' h, rrrJ rrouhiz"me' diÍ-crenriare
i-'o ba-l bulb' under
a p l ' o r n p c r i ol odn s c r h a nl 2 | . Ü d n . e nl r ) - l ) l o n g P h o roo-i..{,nd h,sh nìrroeenlcr<l' ìnhibircJrube'i2r:"nof
f.ilo* nu''.dge'C,,g.i Jl. lr)o-i. H"he\er' low nirrogen
prornor.dtubcriaiev.t'.ombin.d wirL hieh rc r,crarure
.l-"'
ro, tuberi-riÒnol
r
i-o""i",
i .l.o
-ron.Shadine
(Kaley a;d Thullen i978) In an ÌÌlinois
yello*
'"nìy oi""tsàge
on'inuou.,nnr qrrhuurrdcquac nur*dgecon'
r r o l ,r u b e rd c n . i r i e . : n , r e r c 'da p i d y r r r r l r eÍ i n r ' c n o n :
rhen, the densiq' rerminedat abãut 1,000 tub€rsm':fòr
dre next 3 yr (StoÌlerer al. 1979).
Day lengthdoesnot influencctuberforr:rationin purple
* n'".h x nr yellow nnrìèdse.Hotowiú (1972)
".."ág" apparenteÍlec ofa naturâlphotoPeÌiodoí 10 to
found no
14 h on túeriarion in purple nutsedgeln Isracl,establ'.herlpìanr.lormedmore,h,,, 200 new rube' rntl b,vi
r H o , o w i r r/ ' , b 5 Jl.n L ' e n r g i P
, .ì r n r e d , u
ul
b u , b .:
bcrsol r,urplt nuoedecprodu.edl.(roubulb' ,ì-d 1.J00
)0.\ ,Êeì plrri"g. w,rh a dry wershr"lJ lg
-1,",, (Mtr.rdô
r979).
m,
rn ong rhc 'pecie.m.rybc rcLredro f:rru rcid'. ììpid' or
and webcr lo74).
ug.^ in rube^ iSroLler
Ttber Sproutìng
\pf,uí:ns o ruben i. .egulared
b1 apirì d"mìnrn'e
r
u
b
e
r
'
n
r h c . h a i r rr' p i " atlu J '
p
u
r
p
l
ã
r
u
r
*
d
e
e
a
l
i
c
d
\\rrfi
of m"re
ol rhe rrLer 'pr"ui trri,. ;'rhrhlingde'clopmenr
distant buds. \íiú an intact nerwork,quiescenrbuds and
chain tubem remin viabiliry while renÌainingdornÌant tor
prolongedperiods(Mercado1979iStollcL€r â1 1979iWilÌs
1987).
Y . l ì o wn u r * J e eb u d t . u r . r r r r t , c" p i r l e n d" f ' u b t n
-u..dg. r"berubrei,
rwill. r' :i. lo8'0t.BrJ. n 1el.o"
order.rarrirrgwirh he olde't tb-r'
dornr:n.r in a,ropcraJ
peul) bud. turple nut'c,leebud'.lu"o "r rJ'cn"d- rìong
i h e c n . i r el e n q r ht l " u . u l ò ' e . r . ì 1 < r r . l h ( b u d e \ r i h i r '
apic,rÌdominancesincc the most apical buds sprout and
úhibit sproutingof the morc basìpetalbuds (Loustalotet
al. 1954:Smith and Fick 1937).
Under lavohble
conditions,
sprouting can ocou
and a
shooremergesin 4 to 7 d. Shootdoelopment is raPid ln
lìeld studiei, shootsemergefrom tubers a lar as 45 cm
,oronr
betowrìrc."iÌ surfa.crHorow ? tq65ì.Tngeneruì.
e i. ,'a'er íio'
i' hrgher:nd rhoor mergen.
ing peicenrâgr
". c. lpíour,ngcd o(\ uÍ
ruber.lora'edclo\en,o rhe\orl\urlr\
at differenttimesduring úe growingseasonYellownutsedqe rub"- , 'n .prnlr ,, le.nlhree.eprrrrcrime'.con.u-inS
mor rhan<,0o"ofrh. dry reiglr r.rrbohydrrr,oil 'r"r.h
and protein) on the Íìrst sproutìng fhe secondsptouting
useslessther 1070 of theseconstiruentsduring rhe next
rycle((StolleÌcr rì. lq72).
sDroudne
'
\ellownur*dgeruben. ìerì1 Ji.ph1 'c^onrì dornran.y.
havingÌargenunbos of mbersoveminteringwìth a higher
Tubet Langeu;tr
percenrJqe
rq rnanrnn'eprodr.<Jin . u'
o prouungLJprL
In eeneral, rubers rernain dormant in soiÌ tor cxtended
iu-- Lú' :ea" , d ú"|.", to-o; srn ln and V/ar lq-J,
-I"mbles"";".ì
p e r ì o d il." n g , ' i r r o f r u b e n i n r r e r o r ' d e p r hi n ' o i l i n
Kommedahl 1961). In Minncsotâ, onÌy
4
arrd
6
'uben
a
,lfìife
oÉ
rus,dgc
had
\.llo;
i*^",.
12oloof fall-harvestedrubers sprouted comparedrvnh 95olo
cly.irrr r'.n. rop. ', ironmen, ol tl'o- l'*csted io the sprins (Tuoblcson md Konnte
,"" ar l0 âno20, m. ,e.pecri.
in Illinois (StoÌlerand \74 Ì973). Howevet,rn conutuous dahÌ 1962). Purple nutsedgedoes not show any seasonal
corn, moderateÌyinfested with yellow nursedge,at least2 yr
dormancy,as tuberscollectedall yearround from plantsof
.ontroÌ *ere requiredro nJute tub" pnprno mo^rerrperrrr-c
v 'ri^u.,e.. 'proutedundcrrrvorable
"i.cr'"rJo'rg
uìarion'ro 20ìoofrhe originrrden':ry.uhìleJ vr o rrcar- 'u'. .onJi'i"n.. N(wl) forìed rubcr ot purptenur.cdge
nenr reducedtubersby another57o (StoÌÌcret aÌ. 1979). sprcutedreadilnshowingno season:rÌ
dormancy(Horowitz
Other studies have shown that ycllow nutsedgetubers do
1972). This rype of infòrmation on seâsonaldorDìancy
nor li\e onc in 'oil /Thuli,n rd KeeÌello-<ì
couÌd be ioportant in intesmtingapproaús thit mey diDnine tubcn lrom rheirn.,urrl rarc I 8<oowrrertro
prioririeson depÌetingor inhibiting
rect weedmanagement
mois- speciâctubersthrough interferingwith dormmcy.
aboui 15% ''.ist"re will kill úem, and intermediace
rure contents resulted il reduced viability (Rao ard NagadcF
râjân Ì962i Smirh and Fick 1937).IÌì yeÌlowrÌuts€dge,
FutureResearchNeeds
iccatione*ily kìlled tuben nr Illinois (Stoller 1981), but
Às weedscientjstsmoveinto a transitionperiod,research
did not aJIecttubersfrom California,Florida,or SouthAÊ
rica ecotypes(Dav and Rrxsll I955; Thônd 1969).
eflons mrxt focusto unde*tand the bcic bìologyofweeds.
L"neme temp"',t"'." can ldlÌ both yellow ano purpre Biologicalattributesúar are*sociatedwith survivalofweed
must be closelystudied.Methodsmust be developed
nutsedgcrubers (Day and Russeil Ì955r Thomas 1969; species
to predicthow wecdspeciesor populations,nrduding bioThomas and Hcnson 1968). Yellow nutsedgcruberscan
withstand lower temperaturesúan purple ntttsedgetubers.
rypes or ccot,?es, evolve in Ìespotse to selection PressüÌe
DeLker(1997)
via agricuÌturalpracticcs.In this syrnpos;urn,
In a Ìaboratorystudy,50% of tlre purpÌe and yelÌow nutemphasized
the importanceof weedcliversiryin wccd mansedgetuL,emwerc kiÌÌed at 2 xnd 7 C, tespecrìveÌy(Stolltubers agement systems.Uldersranding the genetic diversity and
cr i973). Hôweveain rhe feld, someyellownutsedge
Doeulari"nqenerL vrucrure miqhr Haideour deci.io-r
tolerated-20 C during wìnrer (Stoller1973).Cold hardi'
,t. 'lei,
or riìini"f ,he u'e of hcrbi.idc..
ness of variour ecorypesol yellow nutsedge may pl:ry an
"t'.''
"rlo,"'
piodu,ri"rr
ol
l""d an.l hL,enool'- ro"rrd
À
rhe
within and
imponant roÌeiD longevìtyoftubers.Diflerenc.es
\íeed biology:lnponancero rvecdmanage'nent'
Bhowmikr
353
grearer
\u.,ain'biì'1.weedmdnagerenr
,y.rem,$iìi be.uh
red
ro
mJn) in,ca,J dd e\rernrÌ,o-,.ninr.. t he,ema1
',,
'h.rrpìylirNr rhe
,Jngcot $eeo(un,rol me,hod,.
"varlabl<
Thu'. re-ar,h mu.r dnelop <n!i,o ', enrJly .rlr wccd
Ínrnagem.n,,y\rem,. The I nuledg<o, seed I,iolog]
sould helpin dc,igning,omeot r\c,ã *y,rem,.
R*eu-h ,ÍÌ"'r. mu.r be errc,ded ro idclrif rherol<oi
auxins,.dbÒhrdrarc rcrcncs, od cnvironmental factors and
to understandthc mechanismof roor bud dormancl of
common rniÌkweed.Sinilar dormarcy Drech.rnhms
ofveg
er"rircpr"prgule.olurhcr pcre"nial
'pc.ic,.ouÌd be
"..d
erploì,(d.UndersrdnJing
,he ,ì,cchJni.m
dormJn.yol
"t
veserârive
p,opâsJler
will Jllô$- i-ins ôf m.nrg-m.n,
pry
Ine\. Iniorm ion o- ,l,c incìden.eor cn,roachmenr
oI
mosrpeÌennialweedspecies
in Do-lill or reduceddilagesystems is ÌimiÌed. Each cropping syÍem dealswith speci6c
ril[9. ooeraüon,inLtrrdì-gpri a4 r:tìagr.,c.orrdarlriurge. or r.du.cd .,lLge.FÍÌe.r,or rLc,cril'rge,yvem, on
coÌonizationand persisrence
of perennialspecicsmust be
exmined. The informationon sparialdistributionofspecies
woulct be of grearvalue in making decisionsfor weed rnanagement systenx. Spccilìc managernent mcr;cs could be
basedon spatialdisuiburion.
IÌ1 gen€ÌâI, rhere ir a need to develop managementstraregies for perennid weed speciesundcr an integrated pesr
managemenrsysrern.Th€ inrerâctionsof frequencyof mowing, cuaing height, covercrop residues,and living mulch
on population bioloy ol perennialweedsneed to be explored. As curtent reserrchresulb on weedseedbankdlnam
(mdgcn.c.Jnd d^rmJ"cy
ic,. i,ìJud;ngred diwrìburion.
tu.ror'.begin," uniold.se mu., fo.u, úur arrerrionrn
undenranJrhc dlnamia o'vcgerarive
prop.rgules
oipcrrnnìJ weed,pe.ie'.\Ìrirh úe rdvrncemenr
o'der riledl-ow.
edge about perennial weeds,researchefTorrsmust connnue
to develop.effctivemanagemcut
strategies
lor perenniaÌspec1esrn vânouscroPprngsysrems.
Linite<ì researchhasbeendone on ecotypicor biotypic
variations of weed speciesto identify ecotypesof weed
sp€cìesand Ìheir inÌeractionswirh variousenvironmental
factors.VâriousenvirorÌmentshave diversccÍltcts on the
physiologicalrcsponseofa speci{ìcecorype.Effors shouÌd
be made to deveÌopa systemto categorizerhe ecorypesof
each species.A geographicaÌdistÌibution of ecotypes
could be developcd in reÌar;on ro climaric regions,
nations,and rcgionswithin a nar;on. Such identification
of ecotypeswould allow us to developtargetedmanageMoÌccularbiolosic.l rechniqucscould be usedin rhe investigationof ecorypesor bior'"es (Deld.er 1997; MilleL
1996; Nissenet al. 1995). NÌssenet â1.(1995) indÌcaterl
thât DNA-bâsed mârkeÌ systemscouÌ<Ìbe usedto determine
genetic diversity of weedy species.The information Íiom
theselypesof studiescouÌd be usedin biocontroÌpractices
or ìl othcr alrcrnativemaìagementpÌacticesappropriat€foÌ
Researchefforts must continúe to exploÌe weed seedtank
dynamicsand its impÌicationsfôr predictìngweedseedling
emeÍsence.AÌúoueh we havevarious models (Bridgeset al.
1989:Forcellaet al. 1996;HaLveymd ForceÌla1993rMohler Ì993) ro prcdict weed seedgerminationor seedÌing
emergence,we need to redirect our eÍ+oftsro úe thesemodeh in designingweed managemenroptioDsthat rcsuli in
354 .
45, May-june1997
\íeed Science
optimization of production inputs. Integraredapproaches
that direct priorities toward dcplering weed seedbank
rhroughin,.,le,in8s irh dormJncyor gcrm,ìarionrequiKT(n,. h've gredrpo,en,idlro c h.nce we(d mdJgemenr
srrategresior agnculrurâl sl.srems,
Finally, our researchefforts must focus on economrc
dnát),:.n, weedminJgemcn,ry.,em. if wc rn ro n.rk<
d c c r . ' o no' n
g f a r r rìr, , p u r ,i , , \ - . r J i n i b l (J g r i .
"p'imizir
. , r r , u - c f. c o r o m i . . " ú . , , . , . i
b e b a , c do n r h . e . r r o Ì d
w€ed managcmenrmethods. These methods musr be
basedon rhe effectsof rhresholdrnanasementon weed
population dynamics.To deveÌoprhe populârion-dynamics models,we need der.il.d ìnlormâtion oD weed seed
o r o d u c r ì o n . . e dc id, p c - , a s' .e e dl o n t s e \ i D
r n. d m o \ e m e n ,
uÍ .erd. o. kgerâ"e p,op.,guìcr
in .oiì. ì he.ea.pc.r.of
$crd dc, ograph).on,ri,:re: prrr ofweeJbioio$. \xecd
b i oo g y i . Í c b J , i . i " r
.,n"g.-.", e".i .. tt.
",.d
biolog1of wced. murr be unJenrood :nd rppropriare
managemcntstrategiesmust be developedbasedon cur,
rent and future knowÌcdge.
Acknowlêdgment
MssiclÌusetB AgrlcúlturãÌ E+ernnenr Shtìon Journ.l ArÌi.l€
No.3i16.
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ÂberÌdÌt l. R. ând D. C. Bridg.s. Ìt96. ResearcÌì
priorìq' dy&mi.s in
veed 6cien.e.\íea1Te.1ìnôI.3:396 399.
BeÌI, l{. s., \í. H. Ldrnd, E. M. Rilìn, rìd R. D. Swee..1962.Life
Historf SrudicsâsR.litcd rô WeedConlol in the Northeët. Ì. nuË
gns. KingsÌÒn, RI: RIo{Ìc Isltrnd ÁgÍicultuRl Expeinetrt Srârion
Bú1. 364. 33 p,
B€non,D. L, 1986.Methodsof snìpling s€edbantr in dhlc vìils rviú
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'IlÌe
BhoMrik, I C. 1970.
bioloPJ:Õf únnóí
ni,\kwccd Açkpi6:!iaú
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y/r.z). Rcv of wad sci. 6:227 2t0.
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BhNnÌik, P c. and M. M. Bck.h. 1993.Ho6*eeá lcory/.nnàd.Bi,
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