Tobc,K,Zhangコ
L a n d O m a s a , K . ( 1 9 9 9 ) , SSCcCrガ
注打。
刀οr , 2 7 , 8 5 1 ‑ 8 6 3
cヵEffects Of NaCl on seed germination of five nOnhalophytic
species frorl a Chinese desert environment
K TOBEl,L ZHANG2and K OMASAl,3l Environmental Blo10gy Division,National institute For Environmcntat Studics,16‑2,Onogawa.Tsukuba,
Ibaraki 305‑‑0053,Japan
2 1nStimte of Desert Rcscarch,Chinesc Acadcmy of Scicnccs, 174,Donggang,West Road,Lanzhou 730000,
P.R China
3 PreSent addressi Graduatc School or Agriculture and Lifc Scicnccs, Univcrstty of Tokyo, l―l‑1, Yayol,
BunkyO,ku,1'Okyo l13‐ 8657,Japan″ Cごη rtt FCう″ar/′タタリ

Summary
The cfFects of NaCl on seed BcrlninatiOn were investigated amOng rlve nonhalophytes disttbuted in Chincsc
desert,To evatuate the spcctRc effects orNaCi On the secds,gerrninatiOn,viabi!ity and water uptake of theseeds in NaCi solutions wcre compared with thOse in isOtOnic sOlutions Of polycthylene Blycol‐

6000A The

sccds ofthe nve species in the same habitat showed wide ranges Of difFcrcnces in susceptibility to NaCi b
berorc and aftcr radictc emergencc̲It is sugBestcd that somc spccics distributcd namrally
onsaline in■loca‐
tions are potentiaHy salt̲tolerant in the Bennination stage and can be candidatcs to bc utilized for thc
tation ofve8etation in salinizcd locatiOns.

Introduction
Salinization ofthe soll is a seriOus problem in arid and serniarid rcgions.For species tobecome cstablished in salinc environments,adaptation of the species tO salinity in thegemination stage is crucial(Ungar,1991,1995),TherefOre,to predict the effects ofsalinization ofthe soll on vegetatiOn in these regions,Or to undcrtakc to introduce agro‐
mornically important nonhalophytes tO salinized locations,inforrnation is impOrtant on
how salinity affects thc seed gerrnination ofnonha10phytes distributed in these regions.
In this sttdy,wc investigated the effects of NaC1 0n「l vc species distributed in non―salinc sand dunes in Chinese dese止(Table l).In China,all these nve species serve not
only as livestock feed but also as vegetative cover that stabilizcs sand dunes(Lanzhou
lnstitute of Desert Rescarch,1985).
The effect OF salt on sced gennination is mainly osmotic fOr some specics(Clu帆Evans and Young,1983;Myers and Morgan,1989;Naidoo and Naicker,1992),but fbrothers salt can also cxcrt Salt‐
speciflc effects on the gerFIlinating seeds,Atleast some ofthe salt―
speciflcity is attributable to pemcatiOn of salt intO thc sceds during the imbibio
tion stage. Indeed, solutes can signiflcantly pemeate through the testa of seeds(ManOhar and Heydecker,1964;Manohar,1966),and moistening of seeds with NaC
solution incrcascs the Na content ofthe sceds(BliSS,Platt― Aloia and Tholnson,1986a;
851

K TOBE,L ZHANG AND K OMASATorres―Schumann c″ α″.,1989;Saleki,Young and Lefebvre,1993).When Salt enters theseed tissues,it decreases the、
vater potcntial(均vater up―ィ″)in thC SCeds and promotes、
ta k e b y t h e m ( S h a r T l a , 1 9 7 3 ; R o m o a n d E ddleman,1985;Saleki′
cr α.,1993;Ungar,

EFFECTS OF NACi ON SEED GERMINATION

of Lang(1967)and MiChel and Kaufmann(1973),but the Yw of thc prepared PEG
solutions was flnally deterlnined、 vith an isopicstic psychrometer(BOyer and Knipling,
C under1965)at 20° C.The petri dishes were covercd with lids and rnaintained at 20°

vo thirds thc volumc of the watcr or1995).HoweVer)salt absorbed into sceds can also have toxic effects on the tissuc andcOntinuous darkness in an incubator,About t、reduce the gex‐rninability of thc sccds(Redmann, 1974;Bal and(Chattopadhyay, 1985;
s01ution in each petri dish was rcplaced dally to avoid a change in thc Yw ofthe solution.
H a r d e g r e e a n d E m m e r i c h , 1 9 9 0 ) . I f i m b i b e d s a l t c a n a c t t o X i C a l l y o n t h e Thcs c sceds、
e d g e rvere― considered to have gerrllinated、 vhen thc radiclc length excccded 5 rirn
Ininability)hypersalinity that cOmpletcly inhibits seed gerrnination can alsO be lethal
to
ご
Dpα/″
″初 and 3 mrn for the other four spccies and the radicles showed no ab―for″ ざthc sceds.However,Bliss c″ α′(1986a)b)haVe reported that NaCl inhibits the gerlnina―
norrnalities
tion Of barlcy seeds only osmotically during thc initial imbibition stage,and acts toxl―
″αrデ
θ″
″ざo/‐
初θ冴￠/αr夕y〃 ο″s22冴 g2/初 どcally only by inJuring the emerging radicies.In this case,salt can act toxically only at己xpタガ″2″rプ.・
材r,ο
αr,ο
″?〆αttcな ?〆Sθ′どχαttFれconcentrations that allo、
v the initiation of radicic elongation.It seems that effects of salt
The number of secds sown in each petri dish(inncr diamcteri 90 mm)Was 20 for〃・
on the sceds difttr、
videly among different spccies.
J冴″ or 25 for thc other lour species,Aftcr rnoistening,the number of seeds that
ざごopαンvas counted every day Sor 15‑25 days until the gerHlina―
In this study,to evaluate the speciflc cffccts Of salt on thegerHlinatiOn
seedsぅ
had
gcrHlinatedin each dish、in NaCl
solutions、
vas compared、 vith that in isotonic sOlutions of polyethylene glycol(PEG)― tion percentagc becamc alrnost steady;the gemination perccntage at this tirne is desig―
6000,which cannot pcrlncate plant ccll、
v alls and acts solely as an Osmoticurn on seeds nated as the inal germination percentage(CF̲).Timc needcd for the germination pcr―
centagc to rcach 50° /O of σF(τ′(Shamla,1973;Redmann,1974;Hardegree and Emmerich,1990;Bradford,1995).As―〃)WaS interpolatcd from thc germination perccntagcs at
vo days.
pects investigated in this study included gerlnination in mOderate Vw,effects of pre― the consecutive t、treatlnent with solutions of io、v ¥w On sccd gerttninability, and water uptake by theοw Y 〃 θ″ざ夕冴んs θ′″r J ο
″s ゲ ′″御 r s w ル
sceds in solutions of differcnt Yw.
何どθ″ヴ 研 修c な げ レ/ 2 r 々αどE ヮ θガ″c ″r 2 ・ごχαt t J れれgθ/初!″αr7θ
p e C i e s w c r e m o i s t c n e d f o r c i t h e r 5 d a?yβsα(ガ″H S初ご) O r l o d a y s
T h e s c c d s o f c asぃ

Materials and IIlethods
Seeds of the flve tcsted specics(Table l)Were gathered in nonsaline sand dunes in
Shapotou,China(37° 26′N,104° 57′E).At this site the ground is covered、vith nonsaline
flne sand, and the annual mean temperature and annual precipitation in 1995 were一
9.9°C and 220 Hlln,respectively,Seeds、vere collcctcd in OctOber, 1996 for ri scopα(OthCr fOur spccics)in pCtri dishcs(innCr diametcri 90 mmithc number ofthe sceds
2 MPa
each dish being the samc as that in cxperimcnt l)With‑5,O MPa NaCl or‑5。
vashcd、 vith dcionized、vatcr and trans―
PEG solution.Thcrcafter the seeds、 vere lightly、
vhich they、 vere moistened、 vith delonized、vater.The
fcrred to othcr petri dishes in、
number of gerIIlinated sceds、vas counted for 10 days aftcr transfer,and CFand T7々 aftcr/J切″々transfer were calculatedゃ,October,1995 and Janua電 ん 1996 forズ。θ/がOs,cα,and October,1995 for the otherthree species,Before the experilnents,the sceds were stored dry at aboutC.The
5° ger―α施 妙″g F れ y 〃 ο湾 ッαr C / 呼 どInination experirnents were caried out during thc periodヽ″r ど
θ″ざ冴冴 彦/ ″t J筋
ヵ ο″ ゲ 新 彦C r s ゲ S θ′
在arch 1996‑August 1997.
E I β" ″ 御 r J f t ttα
In all the experirnents,the seeds wcre so、
vn in petri dishes on three layers of fliter ざcctts
αガタ初 sown in each dish(inner diametcri 25 mm)or ten seeds of
50 mm)werc mOistened witheach ofthe othcr four specics in each dish(inncr diamete庄.BeCauseit
hadprovedfroma preliminary experi―
NaCl or PEG solution of known I″v ithin 7 days after
ment that the seed、veight of all these species becomes alinost steady、

paper(Toyo,No,1)mOiStened with delonized water or a solution of NaCl or PEG‑6000,
so that about half the volume of each seed was iHllnersed in the solutiOn. The NaCl
and PEG solutions of known Vw were prepared according to the respective equations

One seed of tt sc?β

Tablc l Characteristics Ofthe flve tested species

moistcning,changes in the weight ofthe secd(s)in eaCh diSh wer

Specles

Fanlily

Lifc

Rettsar″
れS C り, αr2″
閉F i s c h . e t M e y
泌/rc初ェ
s:αθ/ブθSIca Krasch, αs s , αt tsα
押化ガ′α( F i s c h c t M e y ) O K u n t z e

LcguIIlinosac
Compositae
Chcnopodiaceac
Chcnopodiaceae
GraHllneae

shrub

刀g ガ切 り ′′″初 S ? ″α/ r θ
S 夕″ ( L ) M o q .
ア/な r′
冴ααゐ c2″s,οヵお L̲

fomseml― shrub
annualannualannualSccd wcight(mg)*239± 4.8
0.27± 011
097± 022
1 7 8 ±0 . 6 3
1 3 0 ±0 , 2 5before to 7 days after rnoistening with various typcs of solutions.In addition,changes in冴″2、vere rneasured at diffcrent tilnes af―
the weight ofthc samc singic sced ofH scopα/どvith various types of solutions for 7 days,and subsequently transferrcd toter moistening、v as evaluatcd invith dcionized、
v ater.Watcr uptake by the seeds、
fllter papers lnoistened、Wθ)/〃θ
レ
terlns of rclative weight gain(レ,Where w and wθ arer)WhiCh Was calculated as(w―千the seed weights at a givcn timc andjust before moistening,respectively,

辛i mcan tt SD(n=20)
852

853

EFFECTS OF NAC1 0N SEED GERMINATIONK TOBE)L ZHANG AND K OMASA

Results

solutions.句 /2 of the seeds tteated with delonized water(O MPa)waS Within the range

de―
/冴
θ
sたα
〃α)t03.3 days ol,ο.冴αずO.55 day(』)(Figure 2 and Table 2).As y″ン〃ゎ′creased,7′″ガο″s6メ 初οttθ
/α″
で y″ 0″sCCtt g2/初″れαrfο
″/2 increased in both inedia in all the tested species.The relationship between
擁 Cな ザ ハ物C′α″冴Pど C sο′,s?夕α//οざ″初 it becoHles less steep
For И,s?冴αr/θざ″″α,gerlnination was abnorlnal in about 3.50/O ofseeds in that a plumule
竹/2and y″ is steeper atlower values of Yw,butin И.The increases in句″with decreasing y″were mOst pro―at very low values of y″emerged frorn the mptured testa distant from the rnicropyle,while norlnal gerHlination
α Seeds treated with the NaCI solution atof this specics was characterized by radicle protrllsion frorn the rnicropyle.Most Ofthe nounced in』 .冴αsypゎ ,″α:れ ″ Of β・冴αSげpろ ガ″‑2.4 MPa was16.9 days,which was about 30 tilnes longer than thatin delonized、
vater.
abnorrnally gerlninated sceds did not develop into norlnal scedlings.The abnomal ger―
in
PEG
than
in
the
isotonic
NaClsolutions,
′
・
冴
α
α
waS10nger
atiowy″rnination was lnostly detected l‑4 days after seed lnoistening,whereas nomal gerltnina― 句″ Of βツp花 ガ
but ri sc?α /J冴初 SCeds showed longerぅ 〃 in NaCi than in isotonic PEG solutions.Fortion usually occurred more than 3 days after lnoistening.There was no correlation be―
the other three specics,no substantial diffcrencc in r″
τ Was detected between NaCl andtween the pcrcentage of abnomal gerrnination and the type Ofthe solution、
v ith、vhich
PEG treatments.
the seeds had been trcated.Abnormal gerHlination sccmcd to rcsult froHl protrusion of
the cmbryo ttrorn an abraded or cracked part ofthe testa under the turgor pressure ofthe
″αサ
″
ο湾
れげ ↓
″け
Jο
θw Wケ ο″SCCtt gC/初′
んハ4α
C′ο/Pど C sο′rw″″embryo before the turgor pressure pushed the radicle through the rllicropylc.In this
移 Cな ギ pr夕″θαrttc″
During pretreatrnent with‑5.O MPa NaCl and‑5.2 WIPa PEG solutions,sced gerlnina―
study,abnorlnally gerrninated sceds、
vcre excluded froln calculation of the CF andぅ″tion、vas completely supprcssed in all the flve tested species,but transfcr of these sccds
ofИ.ざ?″α//οS冴″・vith delonized、vater resulted in seed germination in rnost situa―
to fliter paper rnoistened、For刀 ,θrttο
sたα,when the seeds were treated with either NaCi solution of y″
10wert i o n s ( T a b l e 2 ) . I n T a b l e 2 , C F a″nodfぅ n o np―
than‑0.4 WIPa or PEG solution of W4″
loWer than‑1,O MPa)sorne or most ofthe radi、
retreated seeds in deionizcd water from
初 ,CF was signincantly
the data in Figure l and Figure 2 are also shown.For r工 scopα /'″cles emerging frorn the seeds were necrotised and ceased to elongateヽ when thc radicle
reduced by pretreatment、 vith PEG solution,and gerlnination、 vas completely inhibited、vas iess than 3 111rn iong;hOwever,the radicies cmcrging from the other sceds elongat―
by pretreatlncnt with NaCl.For allthe othcr ttur spccies,the CF ofPEG―
ed to more than 3 1111n and showed no abnorlnalities.In this study,(『 F ofИ . ο
pretreated seedsraos,cαvas not signiflcantly(P=0.05)lower than those of non―、、vas calculatcd for bOth sceds in、vhich radicle emergencc was visibly evident and those
pretreated sceds.NaCl pretreat―
タ初,ス.ο/冴οsJcα and
二Sc?βαrガ
signiflcantly(P=0.01)10Wered the CFin九
ment,howeverラin which the radicle elongated to morc than 3 rlln、 vithout abnomalities.For all thc//οs夕
初did notshow a sig―
αand
И.s?″α
』.プ
α
↓
′
the
othcr
handラ
ttsccれ
s'0″
な.On
Z.α
seeds ofれ にsc?βα/J″
初,ど 冴αりpり :′α and刀 .αttscc″
s,θ″な,and norlnally gerlninated刀 .
ttpれジ
niflcant
difference(P=0.05)inCF
betweenNaCl
pretreatment
andnopretreatment.
//ο
α
″
々
ざ
S″
SCeds,thc
cmerging
radiclesthat、
vcre visibly detcctable ciongated t0 3 Fnln?″
α and″ .s?″α/rοs″初,角〃 Was signiflcantly shortened by pretreatment
For β.冴αs沖 んy↓′or rnore and sho、ved no abnorlnalities.
with both the NaCl and PEG solutions.However, 句
Figure l shOws changcs in CF with changing y″〃 Ofス ・ο/冴θs,ca seeds was in―
Of PEG and NaCi solutions withcreased by the NaCi pretreatlnent.
which the seeds were treated.WIcan CF of the seeds treatcd with deionized water(0MPa)eXCCeded 89%for all thc tcsted specics(Figure l and Table With2)。 decreasing
yw ofthe rnedia,CF̲of all the testcd specics was initially unchanged,and then gradually Tablc 2 Effccts of pretrcatllacntヽ
vith a NaCl or PEG solution on sccd gemination After moistening、vith a solution of
5 0 MPa NaClor‑5 2 MPa PEG for5 days(HCわdecreased to ncar 00/0(Figure l).BOthatthey″ cF bcgan to decreasc and the y″
which

Sα/″秘 SC?βα/ル閉)Or 10 dayS(othcr SpcCies),thC Seeds wcre trans―verc countcd̲
vatcr,and thereaftcr the numbers of gcrlninated seeds、「
crred to rlltcr papcr moistencd uFith dCionizcd、
at which CF approached 00/。
varied among thc spccies for both treatments(Figure l)ゃ『inal germination perccntages(CF)and times nccdcd for thc gcrIIlination pcrcentagcs to rcach 50%of rlnal gerrnina―
F o r P E G t r e a t m c n t , t h e ayt〃w h i c h C F d e c r e a s e d b y 5 0 0 / O w a s t h c l o w e s t ( a p p r O X i m a t e ―tion perccntagc(τ′々)are shO、vn as mean tt SE(n=4).

ly l.6 MPa)fOrど
冴αり?Йγ〃α and highest(apprOXimately‑0.6 MPa)fOr″.s?″ α〃ο―S″″々,and approxiIIlatcly‑1.2 MPa for thc Othcrthrce spccics.
There、 vas not substantial differcnce in CF of刀.s?″α//οS夕″7 bet、
ween trcatrnents withisotonic NaCl and PEG solutions.Howevcr,for thc Other four species)NaCl and PEG

solutions ofthc same had
y″ different effects On CF.Gerlnination
′
ofゎβ
.冴
αs輝
′
′
αWas

Specles

No pretreatrnent

PEG― pretrcated

NaC卜 pretreated

CF

CF

σ′

950±
ん
姥均パα/″初 SC?βαガ冴腕″イrrc初など
100 0±
αθ/冴θs,cα
βαss,αttα890±
将ゃんノ″α,4g/J?βカソ″″″ s?″α//θS″閉 990±
emerg―
沼/な″Fttα
α
ttsc2ぇ
srθ
″rs
9o o±

勉vourcd more in NaCl than in isotonic PEC}solution,、vhile the othcr three spccies
showed higher CF in PEG than in isotOnic NaCl(Figure l).In.θraOsげИcα)treatment

る″

2.9 135± 0.05
0,0328± 0.0834055± 001
1.0
3.12± 0.06
2,6
168± 0.08

1.43圭0.04
00± 00米 米 ̲
788± 3.1ネ*
5,92±080ネ
308± 013
30ム 0±66*キ
970± 10050± 0.0米
00キ
900± 3.805±96̲0±16168± 0,11本Ⅲ
2.10主0.16辛ネ 968± 21
93.9±2.1545± 47ネ Ⅲ 142主 0.02■
1.58± 0.03
821± 50

with NaCI solutions of lower
y″ than‑0,4 MPa caused the death of most ofthe
ing radiclcs、
ど.冴αりpれガど
αWas distinct from the other four species in that the seeds*i signiflcantly differcnt froH1 4no pretreatl■、vere able to gerlninate at higher salinity(Figure l).
cnt' at P=0.05, **i signiflcantly diffcrent frOIn ̀no pretreatlnent' atof YヶNaCland PEG
句″Ofthe flve species is shown in Figure 2 as a functiOnOfthe854

P=0.01855

K TOBE,L ZHANG AND K OMASAEFFECTS OF NAC1 0N SEED GERMINATION

l.1;the gerlninated sceds gained″ 午quickly in delonizcd、戸ater,but slo、
vly in‑0.9 MPa
PEC}solution,Ho、 vever,in all the othcr trcatlnents,seed gerlnination、 vas completely
different types of solutions ttor 7 days and subsequently moistened、なth deionized wa―
suppressed for 7 days,and the″ 4 beCame steady after thc initial rapid riscs.The stcady―ter.Moistening the dry seeds caused initial rapid increases in'4 in all treatments.灯.
stateレン4r Ofthe PEC卜treated seeds decreased signincantly、 vith decreasing yw(Figure 3a/J夕vith dclonized water and‑0.9 1VIPa PEG solution began toandgcr―
scopα″seeds treated、
4a).For the NaCl treatrnents,therc wcre not signiflcant differences in stcady― state
minatc l day and 4 days aftcr moistening,respectively,whenthe″ン
レ4,waS approxllnately
午amOng the seeds treated、 vith solutions of different yw(Figure 3b and 4a).When theα施 ゥ S C 夕
体切 e c r s ザ 胞 θ α″冴P どC ο ″w αr ヶ η ″Figure 3 shows change over time inン
フ
of
H
SCθ
午
βar,冴初 Seeds which were treated with

︵ ヾ

５
７

︵ ざ

a
停
︵ ぁ毎一 ︶ ＯＥ 一

５
２

︵ ネ範０ ︶ ｏ屋 一
い︶ Ｆ！ 吾 ≡ Ｅ ｂ 的 電︒
５︶ 宮！ 竜 ≡ 宮 る 的 電 Ｅ Ｌ

﹂

a

0

04

08

12

‑16

04

Water potential( MPa )

‑08
‑12
16
Water potcndd(MPa)

‐2

04

‐
08
‑1 2
‑1 6
Water potential(MPa)

‑04

‑2

‑08

‑1 2

16

Watcr potcntial( MPa )

1()D

0

̲04

‑08

12

16

‑04

2

Water potential( MPa )

‐
08
‑1 2
,16
ヽ
Vater potential( WIPa )

‑2

‑04

‑08

‑12

16

̲2

‑04

ヽ
Vater potential( MPa )

‑08

‑1 2

̲16

‑2

Water potential( MIPa )Figurc l Changcs in flnal gcrrnination pcrcentages

1(】
D
︵ ざ

04

‑08
‑12
‑16
Water potential( MPa )

‑2

)and
(CF)With Changing watcr potential of NaCl(●
PEG(○ )solutiOns a:rreゎ ォsα/夕初 sC?βαガタ閉,bi
Иrrg"Is,αθ/どοsica,c:』 ass,αttαsypカソ′′
α,di Иg/,θ―′あ初 S?″α〃θS夕材,e:И ガsrデ
冴α αどscctts,θ″,s.Forノれッ
拡.ο″ダOs,ca,the percentages of thc sccds for、汀hichradicle emergence was macroscopically dctectablc
arc shown M′ith smaller symbols and dottcd lines;
the perccntagcs ofthe secds for、
vhich thc emerging
radiclc elongated to a length excceding 3 mrn are
dcsignated with iargcr symbols and solid lines
Each point rcpresents thc mean of four replications,and bars indicating thc SE arc shown only when the
SE is iarger than point sizeゃeい︵ ふ付０ ︶ の日 一

︶ 宮や ヽ Ｅ Ｅ 心 的 電 ≡ Ｌ

e
856

５
２

電 25

ト
︵ 沐苺０ ︶ ●宮 一

目

鈍

呂50

５
７

︵ぷ ︶にや電ＥＥ心的 電 ﹂ぷ 75

Figurc 2.Tirncs ncedcd for gcrlnination pcrccntages
to reach 50レ6 of thc flnal gcrrnination perccntagcs

12

16

Water potcntial(MPa)

‑2

(T7〃
)as a ttnction of thc watcr potential of NaCl(●)and PEG(①)solutiOns,atガ 協ゥsα/ ″ Sαソαガー
タれ,bi И/r夕
れな,αθ/グθsFcα,c:』 αSS'αttα
卓ン
Pカノ〃α,d:Zgガ qβり ″″″ s?″α//OS夕″,e:И /なrfブ
αα冴ざ
″25H.
cc″s,θ
Each point reprcscnts thc mean of fbur replications,and bars indicating the SE arc sho、
vn oniy、vhen the
SE is iarger than point sizc.ぅ
Vas calculatcd only〃、、
vhen the flnal gemination pcrccntagcs of ali thc
four replications cxccCdCd 200/O.

857

K TOBE,L ZHANG AND K OMASAEFFECTS OF NACi ON SEED GERMINATIONＥヤ
車的 中≡的中
ｏま
〇ぼ
Ｏ＞一
ゃ車一

防

雨︻
Ｏ宮
ｏ電的 ︺
︺
０ま ｏ＞︻一的≡的〇ぼ電的 ︼Ｏゃミ差″ Ｏ＞ ＥＳ一
宮一

崎

毎石ば
ｏま ｏ＞一
宮電軸 ゃ
中
一的一

b

a
012345678910
Time(day)012345678910

1

Time(day)

‑1

̲5

Cl―
treated sceds,the effecty″wasofsignincant(P=0.01)in
β
.冴
α
s湾れ
〃α,И・
s?″
α
r,
ノ
/OS″
閉 and И. αt t s cパタガ
οヵな, a n d ン
4 w a s n O t S i g n i f l c a n t l y ( P = 0 . 0 5 ) a f f e C t ei dn 庄b y y ″SCて
初 and И.οrttosガ
cα.
フ α/J冴

‑3

‑4

‑5

C
‑1

‑2

‑3

‑4

‑5

‑1

Water potential( MPa )

‑3

‑4

‑5

Figure 4.Rclative wcight gain(″4)Of thC Secds of万タr冴
初 sc?βαr,″
初 (a),Иrrcれな,αθrαos,c2(b),ウ SαJass,α あ り〃り ′
あ (C),Иgr,切り ′′夕秘 S?夕ar/θ
S初秘
θ″な (e)aftCr the seeds had(d),and И/なr危脇 彼なcc″sど
been moistcned for 7 days with NaCl(●)Or PEGe0‑2

Water potential(MPa)than fOr the other four spccics.″
treatcd seeds of all thc specics gencrally
4 ofthe PEG―
decreascd with decreasing yF7・Regresslon analysis tO test the signincance(、
在
endenhalland Sincich, 1995)of the relationship between刀 午 and rw revcaled that″ 4 ofPEGぃtreated seeds was signiflcantly(P=0.01)affeCted by Yw in all the flve species.For Nar‑2ヽ
Vatcr potential( MPa )Water potcntial( MPa )再電的 や
Ｏ＞ Ｏ＞一付石宮や
一的中

seeds treated with‑5.2 MPa PEG solution for 7 days wcre transferred to fllter papers
moistened with deionized、 vater, レ
峰 increased quickly and the seeds began to gerlnl―
nate,although the increase in ギ、、
vas slowcr than that of non̲pretreated seeds in delon―
lzed water(Figure 3a).HoWever,transfer of either ofthe NaCl―
treated seeds to delon―
lzed water caused neither a rise inレン
午nor seed gertRnination(Figure 3b).
Figure 4 shows theンフ
午ofthe Seeds offlve species after moistening with NaCl or PEG
solutions of different yw for 7 days.During the trcatlnents,seed gemination of all therlve species was completely suppresscd.For all the species,mean 4 was highcr forthe
NaCl than for the isotonic PEG treatments,The difference inン 峰 betWecn thc treatmcnts
with isotonic NaCl and PEG solutions was conspicuously smaller for И . s?″
αrrο
s″″

,4

苺︻
Ｏぼ
●電∞ 中
●チ の＞︼︺
長的︻sents thc mean of six rcplications,and bars indicating the SE are sho、
vn only when thc SE is iarger than point‑3〇宮〇＞ ●＞一
Ｇ一
Ｆ︼
苺的 ︺
中
一的一

Figurc 3 Rclative wcight gain(″ 午)OVer time Ofrrr26ゥsα/″閉 SC?βα/1″
初 SCeds on iltcr papcrs moistened with
deionized watcr(○ ),a PEG soludon of‑0.9 MPa(□), 1.9 MPa(△ )or‑5.2 MPa(◇)(a),Or a NaCi soludonof l.O MPa(■),‑2.O MPa(▲ )or‑50 MPa(◆)(b).On thc scvcnth day,secds moistencd with NaCl and‑5.2 MPa PEG solutions wcrc transferrcd to rlltcr papers moistencd with delonized water,Each point repre―

‑2

‑1

‑2
̲3
‑4
Water potendal(MPa)

̲5

‑6

‑7

(○)SOlutiOns Of different water potcntials.Each
point represents the mean oF six rcplications, andbars indicating thc SE are shown only whcn the SE
is iargcr than point sizc.

Discusslon
N a C l a n d P E G s o l u t i o n s o f t h e s a m e yc″
aused different effects on the seed of alltested species,indicating that the effect of NaCl on the seeds of these species was not
solely osmotic.First,water uptake by the seeds of all species was lnore favoured in Na―
Ci than in the isotonic PEG solutions(Figure 3 and 4),suggesting that NaCl entered theseeds and a1leviated the osmotic inhibitory effects Ofthe lnedia on water uptakc(Shar̲
858

ma,1973;Romo and Eddleman,1985).
f lFor寛ve
ざc?βα″デ″初, 4 0f approxirnately l.l would corespond to a sufflciently iln―
bibed state at which radicle elongation was able to be initiated(Hegarty,1978;Bliss c″
α′.,1986a,b;Bradford,1995).Though‑1.9 MPa PEG solution was insufflcient for at―taining this level(Figure 3a and 4a),lmbibition ofthe seeds in‑5。 O MPa NaCl solution
resulted in this state(Figure 3b and 4a).ThiS WOuld indicate that a considerable amount859

K

TOBE,L

ZHANG

AND

K

OMASA

ofNaCl entered the sceds Ofthis specics and lowcred the interlal,thusy″facihtatingwater uptake.
Among thc secds ofthc rlve spCCics>the seeds oftt scOpα /げ″″?and И.θ/冴οs,cαsccm
to be highly perrneablc to NaCi because theン フ
ofthe
NaC卜
treatedseeds was not signi←
午
icantly changcd、 vith changing rw,and the diffcrence in″i bct、
veen the isOtonic lNaCland PEG treatmcnts was iarger.For the Other species,theレレ
午ofthe NaCl―trcatcd sceds
decreased with decreasing y″,suggesting that NaCl peIIleation into these seeds wasmorc hmitcd.Especially for tt s?″α/rθ
ざ″れ,the difference inレ,4″
betWeen thc NaCl and
PEG trcatmcnts was smal1 0ver the entire rangc of y″(Figure 4d).ThiS Suggests thttt
NaCl pemcation into the seeds of刀

.s?″

α

//θ

S冴

初

iS considerably lo、

vcr than in the oth古EFFECTS OF NACi ON SEED GERMINATFON

Ross and Hegarty(1979)havC reported that for rnany species,gerinination is initiatedonly at a Vw that is sufflcient to allow thc elongation of crnerging radicles.This seerns
to hold truc in thc prcscnt study for thc othcr four tcstcd spccics,、 vhere all thc emcrging
radiclcs macroscopically dctectable continued to elongatc in PEC}solutions until thcy
vever,thc delc―
ο/冴οざ'ca being the only exception,Ho、
CXCCCded 3 or 5 1nm in length,沼tcrious effcct of Na()l solution on thc radicies of Иvas much more markcd
ごα 、θ/冴οざ′

than that of the isotonic PE()solution(Figure lb).IndCed,‑0,4 WIPa NaCi solution
higher than‑0.8 MPa did nota←
kllled most of the radiclcs,whilc PEG solution of y″
ごα radiclcs would be/冴θざどfcct thcm (Figurc lb)ThC Cffect of PEG solution on the tt ο
osmotic;that is,thc solution、 vould havc causcd dchydration of the radicics,Then,thc
spcciflc toxicity
morc marked dcletcrious edcct of NaC'l on the radicles sllggests salt―

er specles,
For文 ゃざ?″α//οS″″々SeedS,the effect Of Na()lon 6'.、、vas substantially the same as that When sceds of、 vhich the cmerging radicics dicd、
vithout clongation、 vcrc counted asof isotOnic PEG.Shorter句 ″ fOr NaCi than for PEG pretreatmcnt(Table 2)and larger
vecn thc isotonic
having gerHlinated(dotted lincs in Figure lb),the difference in(『F bet、
mean″ 4 ofthe NaCl―treated than of PEG―
treated sceds(Figure 4d)suggCSt that water
NaC)l and PEG treatlllents、 vas smaller,MIorcovcr,it is possible that somc radicles hav―
uptake by the seeds was favoured lnore in NaCi than in isotonic PEG solution.It seems ing emerged frorll the sccds died bcforc reaching a visibly detectable sizc,Silllilarly,for‑1̲2 MPa scemed to actlnore toxically thanthat the slightly higher、vater uptake、
vas not effective tO incrcasc CF ofthis species,For 刀,αttscθ″sザθ″JS,NaCl solutions of‑0.8 to一
工五 ざごOpαrど材陥ぅZ ο 〆びos,cα and泌 .αお cc浴 ,θ″ガs, despite greater vater、
uptake by the
イPa lNaCl solution,、 vherc osmoticvith‑1,0ヽ
that of‑5.O MPa.For example,treatlnent、
seeds in NaCi than in the isotonic PEG solution,CF、v as lower in NaCi than in isotonic
trcatcd sccds at this yル
CF deprcsslon was not conspicuous as seen in the CF Of PEG―
PEG(Figure l).ThiS indicates that NaCl had a toxic effect On the seeds at the stage of(Figurc 2e),deCreased the mean CF t0 7%,whercas prctreatment with‑5,O MPa NaCi
cither initial irnbibition(ShaHna,1973;Hardegree and Enlrnerich,1990))flnal radiclc、
only to 54 50/0(Table 2)ThesC results sug―
solution for 10 days decreased the mean(『ん
cmergence(BliSS cr α ′ラ1986b),or bOth.
/冴οs,cαgcst that NaCi has itturiOus cffects on radiclcs cmcrging frOm the secds oftt θ
Thc pretreatmcnts with NaCl and PEG solutions of 10w y″/2ど″s,θ
s,and dccreascs thc apparent(『F ofthesc specics,According to Bliss
and刀 .αttscσ
prOduced different re―sponscs in the seeds of the flve spccics(Table 2).PECi pretreatinent brought about aゼ″α′ (1986a,b),NaCl inhibits the gcrlnination of barlcy sccds only osmotically duringsigniflcant decrease of(『″2 seeds.The reason for this response is
F only in H scOpα r,冴
thcir initial imbibition stage,and acts toxically only by itturing the emerging radicles.
unclear,but one possibllity is that solute leakage from the secds into the medium(Si―v rllarked inhibition of gcr―sttο″げs scemcd to sho、
ごα and刀 ,αttsccれざどοrttθin this stlldy,И
mon,1974;Hendricks and Taylorson,1976)reduCed the gcrlninability Ofthe seeds.Na―
rlination at the stagc of radicle emergence)although their seeds scemcd to suffer ttrom
Cl pretreatment caused a more marked dccrease in CF in'SCDpα/デ″″2,and Signiflcant
salt toxicity also at the imbibition stage.
CF decreascs inズ .ο/αOざJcαandズ 。αttc″ sガ′
0″どs,for both of which PEG pretreatment、
as no cvidencc that NaCl exerted any toxic cffects on the secds
In this study,there、
did nOt affect CF｀The mOst probable explanation for this NaCl ef‐ fect is that NaCi thatα//ο s″ 初 ,For И .5?材 α//ο S冴 物 ,the Seeds secm to be protcctedof』 .冴 αsッβ んノ〃α andtt s?″has cntercd thc seeds acts toxically on thc embryos before thc initiation of radicle cmcr―
salt perIIleability through the sced coat,and gerlllination offroln salt toxicity byvcr
lo、
gence. HO、 vever, considering that treatlnent、 vith hypersaline solutions resuited in ahighly imbibed state in the seeds of these species(Figure 4a,b and e),the possibility
cannot be completely ruled out that radicic cmergence did bcgin,but that the emerging
radiclcs suffered NaCi tOxicity in this s01utiOn and dicd bcfore the radicle had become
macroscOpically detectable. In any event, hypersalinity irreversibly reduced the seed
Ver pemeation of Na(〕 1gerlninabllity of these three spccies. For И .s?″ α//οS冴″2, 10ヽ
through the seed coat would have protected the seeds frorn salt toxicity during the pre―vould protect the emerging radicles frorll suttering from、the seeds only at higher yル′′
α SCem to bc considerably
salt toxicity,On the other hand,the seed coat of』 。冴αギンフゎ′peIIleablc to NaCl(Figure 4c),HoWCVer,seed gcrlninabihty was not affected after
MorCOVerぅ the seeds werc ablc to ger―moistening with hypcrsalinc solution(TabiC 2)。
m i n a t c i n N a C i s o l u t i o n s w hi it gh h ey r″ t h a n 2 . O M P a ( F i g u r e l c ) , a t W h i C h t h c g evas complctely inhibited,and the radicles
Hlination of seeds of the othcr four spccies、

survived in these solutions.Thus,the tissues of this species scena to have a conspicu…
ously higher tolerance to salinity than those ofthe other four spccies.
vould bc
vhether sccds suffer from salt toxicity、One important factor that deterlnines、In И.ο/冴οざJcα,most of the radicles died in NaCi solutions of y″v
pertlne―
ving
lo、
1。
wer than‑0.4
vith
seed
coats
sho、
salt perrneation through the seed coat.For sceds、
ヽ在Pa,shO、ving that thc seedling radicles Of this species are exceptionally sensitive ability
to
vould
be
protectcd
frorn
salt
toxicity
beforetheradiclesto salt,the cmbryos、
NaCl.Furtherrnore,it is interesting that some radicles emerging froln the seeds of thiscmerged from the seed coats(c.g.ス .ざ?冴α//οS″初 SeedS),whilC the cmbryos in the seeds
species treated with PEG solutlon died in the same media.Hegarty and Ross(1978)and、vith sced coats that are highly perrneable to salt would tend to suffer ttrorn salt tox

treatment with NaCl(Table 2).The maintenance of gerlninability ofど
,冴αず
α
ン
P化ガ′
seeds in hypersalinc solution would have resulted from their NaCitolerance,

860

861

K TOBE,L ZHANG AND K OMASA

before radicle emergence(e.g.」 Scり,α/1i″"Secds).After radicic e10ngation has been
initiated,radicics emerging l儲o■l sced coats are dircctly exposcd tO salt in the cxtcmal
mcdiunl,but this simatiOn is brought abOut only when the salinity in thc extemal medi―
um is decreased.In any event,thc cmbryos wOuld suffer frorrl salt toxicity inside and/Or
outside the secd coa[.Thcrefore,the salt tolerance Of embryo tissues would be another
ilnpOrtalit Factor detemining the susceptibility Of sceds to salinity.The sleds of differ―ent species wOuld show differing degrees Of susceptibility to salt tOxicity both befOre
and aner radicle emergence,dependin8 0n thc salt pemeability ofthe seed coat,and ac―
cordingly would be inhibited frOm establishing themselvcs in saline environments ci̲
thcr before Or afler the start ofgcrFninat10ǹ

EFFECIS O,NACi ON SEED GERMINAT10N
sccdling radicle growth in calabresc(』″aSSFca θ ′?rαcca var italica)and cress(とどf″秘 sarFジ″閉),メ ″″ars
マ″′O/Jθra″ノ,42,1003‑1005
Hendricks,S,B and Taylorson,R B (1976).Variation in gerrllination and anlino acid leakagc of seeds with
rPヵメs,θ
′oず ,58,7‑11
tcmPcrature related to membrane phasc change,Pra″
Lang,A.G.R(1967)(OsmOtiC CoeFflcients and water potenttals oF sodtum chlo点 de solutions from O to
40°C,ガ材sr″
″y。″″
αttα
″α′QだC力τ″rsrヮ
,20,2017‑2023″
客2'Csc″′/7θ
α,ッθ′
カクルθz力,w24Z力j,ソ0′′一J[C力 ,力0″ggttθ∫Lanzhou institute of Desert Rcscarch(1985)Zん
F―J〕SCtence Prcss,Bcもing.
加Sarrッ″閉 L.),Praヵrα
Manohar,M,S(1966),Efrects Of Ⅲ osmotic''systcms on gcrmination of pea(PrS″,71,
81‑86.
Manohar,Mゃ S and Heydcckcr,ヽ V (1964)Effects of water potential on gcrmination of pea sccds,Nar24/で,
202,22‑24″で
2 s c F ?c″
557,
22″
丁
″
容, イカ でど, p p 5 5 3 ‐The sceds of the rlve species collected frOHl the same nonsahnc habitat shOwed acs乃″M e n d e n h a l l , W a n d S i n c i c h , T . ( 1 9 9 5 ) S r arrfなgi″
g α ″″r 力
Prenticc―
Hall,Inc,,Ncw Jersey
widc variety of adaptability to NaCl in the germinatiOn stage.Aithough this study exぃ´′
α″rP々ノSrο
Michel,B E and Kaunttnan,M.R (1973)1‐ he OSmOtic Potenttal orpolyethyicne 31yco1 6000,P′
aHlincd only thc initial stage of dcvelopmcnt,a wide variety in salt susceptibility of theθ
51,914‑916.
′
gノ
s e c d l i n g r a d i c l e.sあ(2es.〃
g .′
β S.ズ
′
ルV
た) s u g g e s t s a w i d e v a r i e t y i n Msy earls ,tB sA uasn d―M o r g a n , W , C ( 1 9 8 9 ) C e r m i n a t i o n O F t h c stao lte、ゃο/ J O s αゎrant erass Diplachne rusca II.Salinity
ceptibility ofthe tissuc amOng the different species.If a habitat Ofthese
specics
is salin―rcsponses,刀″"Jo,/,α′sr″arFαメ,37,239‑251
qメ,οra鴻ゎοsa andr″b材′
Naidoo,G and Naiker,K.(1992)Seed BCrrnination in thc coastal halophytcscヵ
rrrgrθ
lzcd,salt,tOlcrant spectcs(espeCially,β.冴αra)will dominatc thcre over thc Othcr
′
ッ7,ヶ
r/rg′
θcヵf″srrFara,刀比42,217‑229,?冴arFc』θra,りsalt―
susceptible species(eSpecially,刀.ο/ガοsゴcα).It seems that somc species distributed
α′ザ
αどra″JO″r″
Redmann,R E(1974).OsmOtiC and specinc iOn efFects on lhe gerlnination oF alfalfra,Cαnaturally in nonsaline locatiOns arc potentially salt̲tOlerant and can be candidates to be』οraTノ,S2‐803‑808
utilized fOr the rchabilitation ofvegctation in salinized 10catiOns.
sソc″
閉た″rar″ざ)t。
うαr″L.E。 (1985).Gcttnination response of grcascwood(SarCひRomo,JT̲and Eddlemanぅ″α′。
Ma"agで 刑βヵr,38,117‑120″″
tcmpcrature,watcr potcntial and spcciflc tons,y。
/RαttgでRoss,H A and HcBarty,T,W,(1979)SenSitiVity of seed germination and seedling radicie growth to mois―
AckRowiedgements″″αなヴ 』θ′αり ,43,241243
ture stress in some vegetat市
e crop specに
s,メ
ど
ra″
αcapable of germination
馬psis′力α′
Salekiコ
R,Young.P C and Lefebvre,D D(1993)MutantS Ofttr2か
Wc wish tO thank Mr.Li Yttun and other staffs Of Lanzhou lnstitutc of Descrt Rc―
α"r Phys′θ′under salinc conditions,P′ο
gノ,101,839‑845,
search,Chinese Academy Of Sciences fOr prOviding the sceds ofゴ
Sharrna,M.I夕.(1973).Simulation of drought and its effect on geHnination of flve pasture spccics,刀grο″θ″ノ
生 scοβα/ゴ″″7 and И.
″ar1 65,982‑987̲
JO″″
ο″ガοs2cα.
, 32707 ■,m θ
S i m O n , E W ( 1 9 7 4 ) . P h o S p h o l i p i d s a n d p l a n t m c m b r a neew pPcりcr a9 bg ir ls tr t, y7 ,3 肘Herdugo,G
Taro,J̲A.,Moreno,F.J.,Rodri30,R M,Garcia‐
Torres―Schumann,S,Godoy,J A,Pintor―
ReFerences″"ar o/rね″rPれメ豆θr̲(1989)NaCl effects on tomato sced Bcrrnination,ccti activity and iOnθ″a1location,」οg ン,13S,228‑232.
Bal,A,R̀and Chattopadhyay,N C,(1985)EfFect of NaCi and PEG 600o On gcnninatiOn and sccdlingrar力rτ.A(1991),ど ご
rogyヴ ッasc″
α′s,pp 9イ8,CRC Prcss,8oca Raton
Ungar,】?βヵン?βカパjθ
αL.),βどοわgFa Pra″′
growth ofrice(02zα sarルrα
材閉,27,65‑69.
どど
92ッタ′
θ
Ungar,14A (1995).Seed gcrmination and secd―bank ecology in halophytes ln でSを
P″2"ra″どCe/"′‐Bliss,R.D.,Piatt‐
Aloia,K.A.and ThomsOn,Ww (1986a).OsmOtiC scnsitivity in relation to salt sensitivity″αガθ″ぅ( c d s , J K i g c l a n d 6 . G a l i l i ) , p p 5 9 9 6 2 8 , M a r c c l D c k k c r , N c w Y o r k ,in gerrninating barley secds,Pra″r,cer′
α″″ど"ッど″θ"れθ″r,9,721‑725.
Bliss,R.D.,Piatt―
Aloia,K.A and Thomson,WW (1986b).ThC inhibitory effect ofNaCl on barley gcrlni―
natiOn,Prattr,6ゴ
Fα″″E″ソrrO″
閉2″r,9,727‑733
Boycr,J.S.and Knipling,E.B.(1965).IsOpiCStic technique fOr measurin3 1eaf watcr pOtentials with a thcr―
mocouple psychrometer,Pr9cβ「力βし1,″
力zgsりrrカτ
タ肘αrFO″α′】caどθ?″Srar夕s ザ ガ材夕r'Ca,″メゲ ScFe,cβ
り′
S4,1044‑1051.
Bradford,K.J,(1995)Water rclations in sced gerrninatiOn.In最″″Dをッ冴η ″θ″′αヵどCcr閉筋arわ″,(eds.J.
Kigel and G.Galili),pp.351‑396,Marcel Dekkcr,New York̀CluFⅢG.J.,Evans,R.A々 and Young,」 .A.(1983).Desert saltgrass secd gcrmination and scedbed ec010gy,】θ″″″aFヴ 沢α″ge肋 ̀α
力2g2閉2″436,419■ 22
Hardegree,S.P.and Enline五ch,Wゥ E,(1990)PartitiOning water potcntial and speciflc salt efFect on secd ger―mination Offour grasses,メ″,ars Q′』。ね閉
ノj66,587‑585.
Hega守 ,To W,(1978)The physiology of seed hydratiOn and dchydration,and the relation between water
stress and the cont01 0f gerlnination:a review,Pra″,ce′′α"″E■ッF″θ″"?,41,101‑119.
HC8a中 ,T・W・ and Ross,H.A。 (1978),DifFerential sensitiviけtO mOiSmre stress Of seed gerlnination and862863