全 文 ：23卷 2期 草　业　科　学 75　
Vol. 23 , No. 2 PRAT ACULT URA L SCIENCE 2 /2006
草坪园艺
Physiological response to heat stress in　　
tall fescue turfgrasses　　
YU Gao-jing1 , 2 , LIN Wen-xiong1
(1.Ecological Research Insti tute of Fujian Ag recul ture and Forest ry Universi ty ,
Fuzhou 350002 ,China;2. Xiamen H ighw ay Bureau ,Xiamen 361008 ,China)
Abstract:Thir ty-nine ta ll fe scue varieties introduced fr om America w ere dev ided into fiv e eco types , f rom
w hich fiv e cultivar s wer e collected fo r te sting the changes of turf quality , ro ot ac tivity , soluble sugar con-
tent a round years ,meanw hile antioxidant enzyme activity , lipid pro xidation etc under heat stress condi-
tio ns we re tested to o in 1999—2000. The results indicated that changes of roo t activity and content of sol-
uble suga r in the leaves w ere to some ex tent responsible for adjusting the stress-resistance in hea t stres-
se s , It implied that the two par ame te rs had a g rea t effect on the turf quality o f ta ll fescue around the
yea r. I t w as also indicated that the incr easing ra te o f MDA content w as significantly positively co rrelated
with the changes of electro ly te leakage in the leaves o f tur f g rass. When expo sed to 40 ℃ heat str ess , the
re lativ e activities of super oxide dismutase(SOD) and pero xidase(POD) in the leaf of turf cultivar s con-
ce rned w ere significantly nega tively co rrelated w ith malonaldehyde(MDA) and electroly te leakage. Based
on the index of activ e oxygen and electro ly te leakage , the ability of heat tolerance in the five eco types of
tall fescue w as in order:Gooden>Regiment>Tomahawk>SR-8210>Brandy. Fina lly , a r apid accura te
labo rato ry pr ocedure o f measuring turf g rass tolerance to heat wa s also disscussed.
Key words:tall fescue turfg ra sses;r oo t activity;content of so luble sugar;heat stress;antio xidant enzyme;
lipid pero xida tion
CLC:S688. 4　　　Document code:A　　　Article ID:1001-0629(2006)02-0075-10
*　Tall fescue used as a cool-season turfgrass species has increased since the int roduction of turf-ty pe
cultiv ars
[ 1]. It has became a popular co ol-season turfg rass in China. However , cool-season turfg rasse s
of ten suf fer f rom heat stress during summer day s , result ing in turf quali ty and stand loss. The extent
of the problem has increased in recent years , as cool-season turfg rasses are increasingly being g row n in
w arm climactic areas ,beyond thei r normal biolo gical limits in terms o f heat st ress[ 2].
Many phy siological facto rs could involve in heat stress injury , such as inhibit ing photosynthe-
sis[ 3-5] ;limi ting sugar accumulation[ 6]. The adve rse effects of hea t st ress may be related to o xidative to
cell membranes by active oxygen specie s[ 7-10]. Heat st ress induced production of o xygen species inclu-
ding superoxide (O 2 - ), hydro gen pero xide (H2O 2), hydroxyl radical (OH ), and sing let ox ygen
(1O 2). Those f ree radicals are highly reactiv e that may a ttack and damage macromolecules such as lip-
ids ,pro teins , and nucleic acids in living cells[ 11-14]. Plants have developed enzyma tic and nonenzymatic
scavenging sy stems to quench active oxygen species. Supero xide dismutase(SOD), perox idase(POD)
* 收稿日期:2005-10-15
基金项目:福建省科技厅赞助项目(99-Z-101)
作者简介:余高镜(1976-),男,福建莆田人 ,博士 ,主要从事草坪生理生态与养护技术研究 ,已发表相关论文 8篇。
通讯作者:林文雄
76　 PRAT ACULT URAL SCIENCE(Vol. 23 , No. 2) 2 /2006
and catalase (CA T) break down to(O 2 - ) and H2O 2 , respectively[ 8 , 9 , 13 , 15].When plants are subjected to
st ress such as high temperature , the scavenging sy stem may lose i ts function , and the balance be tw een
producing and quenching active oxygen species can be disturbed , resulting in oxida tive damage[ 9 , 10 , 16] .
Central to heat tolerance in plants are cellular membrance sy stems which remain functional during heat
st ress. whether the adve rse effects of heat st resses on different ecotypes of tall fescue involve oxida-
tive st ress w hich are related to changes in protective enzyme activity and antio xidants have no t been
examined. Meanwhi le a long-term solution to the heat st ress problem will require development of
heat-tolerant cultiva rs , for this purpose , it has made g reat efforts in turfg rasses breeding using field se-
lection and evolution ,but it appea red to be inef ficient ,because of unpredictable heat st ress events and
interaction wi th othe r environmental facto rs , typically requiring yea rs to make effect ive selection. It
w as also to find a rapid and accurate w ay fo r measuring tall fescue heat tolerance based on the resul t of
our study.
The objective of this study w as:(i) to ex amine the changes of f ive tall fe scue cult ivars in turf
quali ty , soluble sugar accumulation and ro ot activi ty around the year. (ii) to investigate changes in ac-
tivit ies o f pro tect ive enzymes , plasmal membrane permeabi li ty , lipid peroxidation in f ive tall fescue
cultiv ars subjected to heat st ress.
1　MATERIALS AND METHODS
1. 1 Plant Materials　T he study w as conducted at Fujian Ag riculture and Fo rest ry Universi ty ,
Fuzhou , China , in 1998—2002.
Thirty-nine tal l fescue va rieties w ere int roduced from America for studing bio-characteristics in
the experimental farm of Fujian Ag riculture and Forest ry U niversty respectively in September , 1998.
Eleven main character s including visual quality , densi ty , tex ture , co lor , t raff ic tolerance , elastici ty ,
grow th rate , coverage , turf fo rmation speed , leaf area index and tilling capacity of all varieties w ere
reco rded. Based on perfo rmance of the eleven characte rs of pe rfo rmance , these varieties could be dev-
ided into f ive eco types at the crite rion 5. 4 w ith the aid of cluster analy sis[ 17] , one cul tivar as the best
representive in each ecotype w as selected for this study , and the file selected culutivars were Gooden ,
Regiment ,SR-8210 ,Brandy , and Tomahawk.
1. 2Experiment 1　The turfgrasses o f each entry w as seeded in Sep. ,1998 , at a rate o f 30g /m2 , in a
randomized comple te block design wi th four replications. The area o f each plot w as 2 m×3 m. During
the establishment , the soi l w as kept moist by i rrig ation , the g rasses w ere clipped w eekly at 5 cm
height , except in summer at 6 cm. The g rasses w ere evaluated in 2001 , the record of air temperature in
the experimental farm throughout expe riments was in table 1.
Turf quality as an integral o f co lor ,uniformi ty , and density w as rated visually on a scale o f 1 to 9
w here 1 represents brow n ,dormant turf and 9 represents the best quali ty[ 18]. The minimum acceptable
quali ty level w as 6.Based on the changes of air temperature in Fujian , turf quali ty w as tested in mid-
month of Jan. , Mar. , May , July ,Sep. ,Nov. respectively.Roo t dehydro genase activity and soluble sug-
a rs w ere de tested on the same day.
Roo t activity analy sised by t riphenyl tet razolium chloride (TTC)me thod[ 19 , 20] , the dehydrogenase
activi ty is related po sitiv ely to respi ration capacity , which has been used in the study of the viability of
dif ferent tissues , such as seeds , leaves , and roo ts[ 19-21]. To determine the activi ty of roots in a sample ,
2 /2006 草　业　科　学 (第 23卷 2期) 77　
the roots w ere first w ashed free of soil , and the f resh weight w as determined. Roo ts then w ere placed
into test tubes w ith 0. 4%(w /v) T TC in 0. 06 M Na2HPO 4-KH 2PO 4 , and the tubes were incubated in
a dark remained a t 37 ℃ fo r 3 h , Sulphuric acid w as added to stop the reduction , water-inso luble red
compound , formazen , formed from the reduction of T TC by dehydrogenase enzymes in ro ots , was ex-
t racted by ground the roo ts wi th ethy l acetate. The abso rbance of the ex t ractants was reco rded at 485
nm w ith a spect rophotomete r (Model U-1100 , Hitachi , Tokyo). The reduct ion of TTC w as analysed
by comparison to standards and the roo t activi ty w as expressed as the reduced amount of TTC against
roo t weight.
Table 1　The record of air temperature in the experimental farm around the year in Fuzhou,China
Yea rs Month Average tempera tur e(℃) H ighe st tempera true(℃) Low est tempe ratrue (℃)
1999 Jan. 12. 5 16. 6 9. 6
Feb. 14. 8 21. 7 11. 0
M ar. 14. 7 19. 4 12. 0
Apr. 18. 9 23. 8 15. 3
May 22. 0 26. 5 18. 7
June 27. 4 31. 9 24. 3
July 28. 5 33. 0 25. 5
Aug. 28. 3 33. 2 24. 4
Sep. 27. 1 31. 6 23. 7
Oct. 21. 9 26. 6 19. 0
Nov. 18. 9 24. 0 15. 5
Dec. 14. 6 18. 2 12. 9
1. 3 Experiment 2　This experiment w as conducted to further study the mechanism of eco logical a-
dapt ion in turfg rasses of tall fescue exposed to dif ferent temperatures in laborato ry. The g rasses w ere
seeded in Sep. ,2000 , at a rate o f 30g /m2 in 15 cm diameter by 60 cm deep po ly viny lchlo ride (PVC)
po t filled wi th soil f rom the expe rimental farm as mentioned above. All the management practice s
were the same as experiment 1.
The experiment w as designed in four t reatments of contro lled tempe rature , w ith four replicates.
The temperature t reatments w ere 15 ,25 ,35 and 40 ℃ respectively , which are based on that 15 ℃was
the opt imum range fo r the g row th of coo l-season g rasse s , and 40 ℃ commonly occurs in w arm climatic
regions during mid-summer , specially in Fuzhou , southeast o f China. The turfg rass in pot w as exposed
to dif fe rent temperature t reatments for 24 h , then the leaves of turfgrasses w ere sampled fo r physio-
chemical assay.
Cell membrane stability w as est imated by measuring elect roly te leakage (EL). Samples o f 0. 1 g
of f re sh leaves were rinsed w ith deionized w ater , then immersed in 20 mL o f deionized w ater , and sub-
jected to a vacuum o f 48 kPa fo r 15 min. The leaves in tubes w ere shaken in flasks wi th deionized w a-
ter on a shaker table (Lab-Line Inst ruments , Inc. , Melro se Park , IL) for 24 h. The conductivity of
the solution (C initial)was measured using a conductivity me ter (YSI Model 32 , Yellow Spring , OH).
The leaves then w ere killed by autoclaving at 140 ℃ for 20 min. The conductivity of killed tissue s
(Cmax) was measured. Relative EL w as calculated as the percentag e of C initial over Cmax.
To ex tract ant ioxidant enzymes , 0. 5 g fresh leaves randomly sampled f rom plants in each entry
were ground to pow der wi th liquid ni tro gen in a mortar and mixed w ith 8 mL o f 50 mM cool phosphate
78　 PRAT ACULT URAL SCIENCE(Vol. 23 , No. 2) 2 /2006
buf fer ( pH 7. 0 , containing 1%(w /v) po lyvinylpyr rolidone). The homogena te w as centrifuged at
15000x g for 20 min at 4 ℃. The supe rnatant w as used fo r assay s o f enzyme activi ty and lipid perox i-
dation.
The activi ty of SOD was dete rm ined by measuring its abi li ty to inhibit the pho to reduction o f ni t ro
blue tet razolium (NBT) following the method of Giannopolit is and Ries[ 22]. The react ion solution (3
mL) contained 50μM NBT , 1. 3 μM ribo f lavin ,13 mM methionine ,75 nM EDTA , 50 mM phosphate
buf fer (pH 7. 8), and 20 to 50μL enzyme ex t ract. Test tubes containing the reaction solution and leaf
or roo t samples w ere irradiated under a light bank (15 fluorescent lamps) at 78μmol /(m 2 s) fo r 15
min. The absorbance of the i rradiated and nonirradiated so lution at 560 nm was determined w ith a
spect ropho tometer (Hitachi U-1100 , Tokyo , Japan). One unit o f SOD activi ty w as defined as the a-
mount of enzyme that w ould inhibit 50% of NBT photoreduction.
Act ivities of catalase (CAT) and peroxidase (POD) were measured using the method of Chance
and M aehly w ith modi ficat ion[ 23] . The CAT reaction so lut ion (3 mL) contained 50 mM phosphate
buf fer (pH 7. 0),15 mM H2O2 , and 0. 1 mL enzyme ex tract. Reaction w as initia ted by adding enzyme
ext ract.Changes in absorbance of the reaction so lution at 240 nm were reco rded every 20 s. One unit
CA T activity w as defined as an absorbance change of 0. 01 △OD value pe r min. The POD reaction so-
lut ion (3 mL) contained 50 mM sodium acetate buffer (pH 5. 0), 20mM guaiacol , 40mM H 2O 2 , and
0. 1 mL enzyme ex t ract. Changes in abso rbance of the reaction solution at 470 nm were de termined ev-
ery 20 s. One unit POD activity w as def ined as an abso rbance change o f 0. 01 △OD value pe r min.
The specific activi ty of each enzyme w as expre ssed on a protein basis. Protein concentr ation of
the crude ex t ract w as measured by the me thod of Bradford
[ 24].
The relative activity of each enzyme w as expressed by the act ivity o f each enzyme in higher tem-
perature treatment o ver the act ivity at 15 ℃.
The lipid peroxidation level w as determined in terms o f malondialdehyde (MDA) content by the
method o f Dhindsae t al. [ 25]. A 2 mL aliquo t of enzyme solution w as added to a tube containing 1 mL
20%(v /v) trichlo roacetic acid and 0. 5%(v /v)thiobarbi turic acid. The mix ture w as heated in a w ater
bath at 95 ℃ for 30 min , cooled to room temperature and then centri fuged at 10 000x g fo r 10 min.
The abso rbance of supernatant a t 532 nm was determined and the nonspecific absorbance at 600 nm
was subtracted. The MDA content w as calculated by the extinction coef ficient of 155 mM /cm[ 26].
2　RESULTS
2. 1 Change of turf quality in year around　Turf quali ty in dif ferent cultiv ars varied w ith the sea-
sons of a y ear in the same trend(Fig. 1). It pe rfo rmed bet ter in Jan. , Mar and Nov. , but w o rse in
May , July and Sep.. The analy sis of comparison among the entries indicated that the cultivars exhibi-
ted their different level of quali ty in that Gooden w as the best , and the reverse w as ture in the case of
S R-8210 and A TF around the year. In the period f rom M ay to Sep. the five cult ivars o f tall fescue un-
der consideration show ed thei r di ffe rent turf quality levels in the fo llow ing order:Gooden>Regiment
>Tomahawk>SR-8210>Brandy.
2. 2 Change of root activity　The same trend as turf quality w as found in the roo t activity of each
entry(Tab 2)that the roo t activi ty of all cult ivars w as the low est in Sep. and the highe st in M arch ex-
cept that Gooden performed the highest ro ot activity in Jan. and the roo t activi ty w as signif icantly and
2 /2006 草　业　科　学 (第 23卷 2期) 79　
Fig 1. 　Turf quality of different cultivars in diffirent time in 2001
constant ly higher in the t ime courses except in May , i t w as no t significant ly different around the year s
in Regiment and Tomahawk , in w hich markly higher roo t activity than w ere detected that in SR-8210
and Brandy , Brandy exbihited i ts lowest activi ty , a round the year , suggesting that Gooden Regiment
and Tomnhawk had bet ter adaptabi li ty to the local environment , The reverse w as ture in SR-8210 and
Brandy.
Table 2　The root activity of dif ferent cultivars in different time courses* μg /(g h)
Cultivar s Jan. Mar. May. July. Sep. Nov.
Gooden 128. 16a 111. 10a 66. 36a 38. 92a 29. 89a 47. 32a
Reg iment 84. 70b 96. 48b 66. 38a 21. 49b 17. 23b 41. 89b
SR-8210 48. 10c 87. 11c 65. 32a 9. 66c 8. 36c 28. 75c
Brandy 38. 50d 64. 92d 40. 92b 7. 42d 5. 97d 28. 11d
Tomahawk 82. 82b 94. 80b 66. 72a 22. 19b 16. 74b 41. 63b
*Data in letter are the means of four replicats. Means in a column follow ed by the same letter are not significantly differ-
ent at 5%, according to Fisher’ s P ro tected LSD Test.
2. 3 Analysis on peroxidation in different turfgrasses exposed to temperature stress　Change s
of elect roly te leakage in the leaves of dif ferent turfgrass cultivars exposed to different temperature s
w are show ed in Tab. 3 , i t indicated that EL value w as increased wi th the t reatment temperature in-
creasing in the same trend in all entries. However , EL dif ferences at 15 ℃ and 25 ℃ treatment condi-
tions w ere less pronounced during vegetative g row th and hence the condi tion of heat st ress w ere favo r-
able for g row th and development in all cul tivars conce rned , larg e differences w ere found among all cul-
tivars under the higher temperature conditions at 35 ℃ and 40 ℃, suggsted that they unfavo r the
grow th o f tall fescue.Gooden , Regiment and Tomahawk performed the bet ter physiological status in
terms of low er EL and its increasing rate , implying that the three turfg rasses could be thought of as
the cultivar s that are heat-tolerance in summer days because of their higher adaptability to heat st res-
ses.
The result also revealed that the change pat tern of MDA in all cultivar s under dif ferent tempera-
tures w as found in the same trend as EL and i ts increasing rate , indicat ing that Gooden , Regiment and
Tomahawk had much lowe r level in MDA content and its increasing rate , the reverse w as true in
Brandy and SR-8210 under heat stresses at 35 ～ 40 ℃(Tab 4). It furthe r confi rmed tha t Brandy and
SR-8210 we re sensitive to higher temperature st resse s , which w as att ributed to higher lipid peroxida-
80　 PRAT ACULT URAL SCIENCE(Vol. 23 , No. 2) 2 /2006
tion induced by heat stresses in turn leading to increased MDA content , consequently resulted in dam-
aged plasma membrane and enhanced EL.
Table 3　Changes of Electrolyte Leakage in the leaves of different cultivars exposed to dif ferent temperatures* %
Tempreature
Gooden
EL IR
Regiment
EL IR
S R-8210
EL IR
Brandy
EL IR
Tomahaw k
EL IR
15 ℃ 4. 64 5. 48 4. 60 4. 43 4. 70
25 ℃ 4. 68 0. 86 5. 80 5. 84 4. 99 8. 48 4. 80 8. 35 4. 88 3. 83
35 ℃ 6. 82 46. 98 6. 95 26. 83 8. 00 73. 91 7. 19 62. 30 7. 21 53. 40
40 ℃ 8. 97 93. 32 10. 80 97. 08 10. 70 132. 61 11. 25 153. 95 9. 17 95. 11
　*EL=Elec trolyte leakage.
　increasing r ate=(electr oly te leakage in dif fe rent tempera ture-electro ly te leakage a t 15 ℃) /electro ly te leakage at 15 ℃.
Table 4　 Changes of Malondiadehyde(MDA) content in leaves of different cultivars exposed to different temperatures*
Temperature
Gooden
MDA Content
(μmo l /g)
IR
(%)
Regiment
MDA Content
(μmo l/g)
IR
(%)
R-8210
MDA Content
(μmol /g)
IR
(%)
Brandy
MDA Content
(μmo l /g)
IR
(%)
Tomahaw k
M DA Content
(μmo l /g)
IR
(%)
15 ℃ 13. 02 11. 28 10. 88 9. 59 10. 82
25 ℃ 16. 76 28. 73 15. 00 32. 98 13. 47 23. 81 10. 93 12. 93 14. 20 31. 24
35 ℃ 26. 19 101. 15 31. 89 182. 71 37. 14 241. 36 41. 90 336. 91 28. 33 161. 83
40 ℃ 37. 71 189. 63 45. 56 303. 90 67. 93 570. 50 55. 04 673. 93 40. 00 268. 71
　*EL=Elec trolyte leakage.
　increasing r ate=(MDA content in diffe rent temperature - MDA content a t 15 ℃) /MDA content at 15 ℃.
2. 4 The performance of antioxidant Enzyme Relative Activity in turf cultivar exposed to dif-
ferent temperature　Biochemical analyses indica ted that the antio xidant enzyme relative activi ties in
all ent ries had a signi ficant increase f rom 15 ℃to 40 ℃(Fig. 2 ～ Fig. 4) and less differences in the rela-
tive activi ties of antioxidant enzyme SOD and POD were found among all cult ivars subjected to 15 ～
25 ℃ condi tions;how eve r CAT performed signif icant dif ferences among all cultivars in that the rela-
tive enzyme act ivities of SR-8210 and Brandy w ere much low er than that of the other cult ivars under
the same treatment temperature of 15 ～ 25 ℃. There w ere pronounced dif ferences in the relative act ivi-
ties of the enzyme among all ent ries exposed to 25 ～ 40 ℃ conditions , showing that Gooden increased
much more rapidly than the o thers in SOD relative activity w ith temperature increasing , Tomahawk
and Rigment showed insignificant dif ference but much low er than Gooden. The tw o cultivar s had
higher activi ty of SOD than SR-8210 and Brandy. SR-8210 exhibi ted the low est activitiy o f SOD (Fig
2). Especially f rom 35 ℃ to 40 ℃, bo th SR-8210 and Brandy had dramatic decrease in SOD relative ac-
tivit ies w here the others st ill kept markedly increasing in that signi ficant differences of SOD relative
activi ty w ere found in the entrie s , indicating that SOD relative activi ty w as in the o rder of Gooden>
Tomahawk>Regiment>Brandy>SR-8210.
In terms o f POD relative activity ,Gooden and Regiment had much highe r relative activity , where
as the o ther three cultivar s show ed insignificant difference f rom 25 ℃to 35 ℃(Fig. 3).But f rom 35 ℃
to 40 ℃, the cultivars of turfg rass had a pronounced increase in the relative activity o f POD except
S R-8210 and Brandy in that Gooden had the highest relative act ivity , Tomahawk perfo rmed the act ivity
higher and Rigement exhibi ted in the 3 rd place especially at 40 ℃ t reatment.
The response o f CA T relative activity to tempe ra ture t reatment f rom 25 ℃ to 40 ℃at 25 ～ 40 ℃
2 /2006 草　业　科　学 (第 23卷 2期) 81　
was less different f rom those o f SOD ,POD (Fig 4).Brandy showed the highest CAT relative activi ty
e xcept that less difference w as found compared w i th
Gooden and Tomahawk especially at 40 ℃ treat-
ment , and the activity in all cul tivars increased in the
relative activity o f CA T w ith the temperature in-
creasing except that of SR-8210 , which had a pro-
nounced decrease f rom 35 ℃ to 40 ℃.
This finding suggested that the turfgrass of tall
fescue , Gooden , Tomahawk and Regiment had the
higher relative activity of antio xidant enzyme which
resulted in low er free radical contents , in turn lead to
decreased MDA content and low er EL value , especial-
ly in heat stress condit ions(35 ～ 40 ℃). The result
helps explain the higher adaptability of th ree culti-
vars to heat st resses.
Fig 2　Changes of SOD relative activity in leaves of
different cultivars exposed to dif ferent temperatures*
Fig 3　Changes of POD relative activity in leaves of different
cultivars exposed to dif ferent temperatures*
Fig 4　CAT relative activity in leaves of different
cultivars exposed to different temperatures
3　DISCUSSION
The assessment of heat tolerance in five tall fescue eco types int roduced from USA revealed signif-
icant differences in genetic po tential fo r heat tolerance wi thin the se species. The resul ts show ed that
all cultiva rs of tall fescue concerned declined its turf quality in the pe riod f rom M ay to Sep. , it sugges-
ted that the the period is the main facto r that af fects the turf quali ty in Fujian , China. In heat months
f rom M ay to Nov. turf quality of five cul tivars w as in o rder:Gooden >Regiment >Tomahawk >
SR-8210>Brandy.
Our study also revealed that posi tive correlation existed be tw een ro ot act ivity and turf quali ty.
that is , the highe r roo t act ivity and the bet ter turf quality alw ays go tog ether. T his finding suggested
that root activity could be used as an important phy siolog ical indicator for the evaluation o f adaptabili-
ty to enviroment conditions in year around. The highe r root activi ty is co rrelated w ith the higher up-
take ability in turfgrasses , and hence the bet ter turf quality w as the result.
82　 PRAT ACULT URAL SCIENCE(Vol. 23 , No. 2) 2 /2006
It w as also indicated that the roo t activiy of tall fescue we re signif icant ly affected by the tempera-
tures around the year , and dif ferent cultivar o f tall fescues different in heat - tolerance , which may be
related to the protective mechanism in st ress condit ions. Plants adopted di fferent protective mecha-
nisms to scavenge the f ree radicals produced under heat st ress. Antioxidant enzymes a re the most cru-
cial among them. Supe ro xide dismutase is the key enzyme in the active oxygen scavenger sy stem be-
cause it catalyzes superox ide f ree radical dismutation into H2O2 and O 2 [ 8 , 9 , 12 , 13]. Both Catalase and per-
oxidase consti tute a set o f enzymes that catalyze the oxidation o f subst rates by H 2O 2 ,break down and
detoxif ie s H 2O 2
[ 15]. Thus , decreases in POD and CA T activity w ould result in H2O2 accumulat ion ,
which can react w ith (O2 -) to produce hydro xy l-f ree radicals via the He rbert-Weiss reaction[ 8 , 9]. The
hydro xy l - f ree radicals can directly damage the membrane by at tacking unsaturated fat ty acids of lipid
to induce lipid peroxidation[ 27].
In our studies , in the t reatment of 25 ～ 35 ℃ all cult ivars had a significant increase in relative ac-
tivity of SOD , which resulted in H 2O 2 accumulation , in turn induced higher activi ties of POD and
CA T , then low er MDA and EL could be the resul t. it appears to be a reduction of SOD relative act ivity
only in bo th Brandy and SR-8210 when expo sed to heat st ressat 35 ℃and 40 ℃, which might be at-
t ributed to either decreased synthesis or enhanced gradation of the enzyme(Fig 2), in turn resuted in
low er increasing rate o f POD relat ive activi ty and reduced CA T relative activity than the o ther three
cultiv ars(Fig 3 and Fig 4). It has been repo rted that the decline in CAT relat ive activi ty w as responsi-
ble for pho toinactivation
[ 28 , 29] , which may lead to the accumulat ion of H 2O 2 and causes damage to cell
membranes
[ 25].
The resul t also showed that EL value and MDA content alw ay s w ent toge ther and increased in the
leaves of all cult ivars exposed to heat st ress , pe rfo rm ing significant ly posit ive co rrelat ion betw een in-
creasing rate of EL and tha t o f MDA content(r*=0. 914 8). It has been documented that malondial-
dehyde (MDA) is a product of pero xidat ion of unsaturated fat ty acids in pho spho lipids and is responsi-
ble fo r cell membrane damage[ 30].Heat st ress increased MDA content in tall fescue simila r to what has
been found in other species
[ 31]. Reduced cel l membrane stability could have resul ted f rom lipid perox i-
dation of membranes caused by active oxygen species[ 7 , 25 , 32] . It w as also found that heat st ress de-
creased antio xident enzyme activi ty , and high f ree radical could be the result. However i t appears to
be highly dif ferent in the decreasing rate o f ant ioxidant enzyme act ivity in the turf grass culiv ars con-
cerned when expo sed to st ress condi tions , which w as at t ribuded to dif ferent abilities of heat-tolerance
in different cultiva rs.
It therefo re can be concluded that the increasing rate of EL and MDA content w ere signif icantly
negat ively related to relativ e act ivity o f SOD , POD and turf quality. Gooden had the best turf quality
in heat st re ss conditions because o f EL and antiox idant enzymes , it had the low est EL increasing rate s
and the highest SOD and POD rela tive activi ties in the turfg rasses of tall fe scue expo sed to tempera-
ture st ress. Regiment perfo rmed bet ter than Tomahawk because of low er EL increasing rate especially
at 35 ℃ t reatment , although the o ther phy siological data showed insignificant dif ference. Fo r the
same reason Brandy pe rfo rmed the w or st , especially in heat st ress condit ions at 35 ～ 40 ℃.
In summary , turf quality and heat to le rance w ere de termined by complex factor s , in present study
we observed the di fferences in turf quality and heat to lerance among the five ecotypes of tall fe scue ,
2 /2006 草　业　科　学 (第 23卷 2期) 83　
which st rongly suggests that dif ferences in genetic potent ial for heat tolerance exists wi thin that spe-
cie s. Screening of five eco types w ill provide an assessment of the ex tend of variation of heat tolerance
and associated biochemical changes in turf-ty pe tall fescue.A rapid ye t accurate labo rato ry procedure
of measuring turfg rass heat to lerance can be obtained , through examining the change of EL and antiox-
idant enzymes activity.
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高温胁迫下高羊茅草坪草生理特性研究
余高镜1 , 2 ,林文雄1
(1. 福建农林大学生态研究所 ,福建 福州 350002;2. 厦门市公路局 ,福建 厦门 361008)
摘要:从美国引进的 39个高羊茅草坪草种分成了 5个生态类型 ,在 1999—2000年从每类中找出一个具
有典型性状的草种 ,测定其周年草坪坪质表现 、根系活力 、叶片可溶性糖含量变化 ,同时测定各类草种在
高温胁迫下保护酶活性与质膜透性的变化。结果表明 ,根系活力及可溶性糖含量在一定程度上影响着
草坪坪质的周年变化 。同时 ,草坪草叶片 MDA 含量的增长率和草坪草叶片的质膜透性增长率具有显
著的正相关效应 。在 40 ℃高温胁迫下 ,草坪草叶片 SOD与 POD相对活性和 MDA 含量的增长率及
PMP 增长率具有显著的负相关效应 , 5个草种对高温的抗性能力大小顺序是:Gooden>Regiment>
Tomahawk>SR-8210>Brandy 。在此基础上 ,最后对草坪草抗性的准确快速检测方法进行了讨论 。
关键词:高羊茅草坪草;根系活力;可溶性糖含量;热胁迫;保护酶活性;质膜透性