高温胁迫下高羊茅草坪草生理特性研究_英文_

23卷2期草　业　科　学75　Vol123,No12PRA TACUL TU RAL SCIENCE2/2006

草坪园艺

Physiological response to heat stress in tall fescue turfgrasses

YU Gao2jing1,2,L IN Wen2xiong1

(11Ecological Research Instit ute of Fujian Agrecult ure and Forest ry University, Fuzhou350002,China;21Xiamen Highway Bureau,Xiamen361008,China)

Abstract:Thirty2nine tall fescue varieties introduced from America were devided into five ecotypes,f rom

which five cultivars were collected for testing the changes of turf quality,root activity,soluble sugar con2

tent around years,meanwhile antioxidant enzyme activity,lipid proxidation etc under heat stress condi2

tions were tested too in1999—20001The results indicated that changes of root activity and content of sol2

uble sugar in the leaves were to some extent responsible for adjusting the stress2resistance in heat stres2

ses,It implied that the two parameters had a great effect on the turf quality of tall fescue around the

year1It was also indicated that the increasing rate of MDA content was significantly positively correlated

with the changes of electrolyte leakage in the leaves of turf grass1When exposed to40℃heat stress,the

relative activities of superoxide dismutase(SOD)and peroxidase(POD)in the leaf of turf cultivars con2

cerned were significantly negatively correlated with malonaldehyde(MDA)and electrolyte leakage1Based

on the index of active oxygen and electrolyte leakage,the ability of heat tolerance in the five ecotypes of

tall fescue was in order:G ooden>Regiment>Tomahawk>SR28210>Brandy1Finally,a rapid accurate

laboratory procedure of measuring turf grass tolerance to heat was also disscussed1

K ey w ords:tall fescue turfgrasses;root activity;content of soluble sugar;heat stress;antioxidant enzyme;

lipid peroxidation

C LC:S68814 Document code:A Article ID:100120629(2006)022*******

3　Tall fescue used as a cool2season t urf grass species has increased since t he int roduction of t urf2type cultivars[1]1It has became a pop ular cool2season t urf grass in China1However,cool2season t urf grasses often suffer f rom heat st ress during summer days,resulting in t urf quality and stand loss1The extent of t he p roblem has increased in recent years,as cool2season t urf grasses are increasingly being grown in warm climactic areas,beyond t heir normal biological limit s in terms of heat st ress[2]1 Many p hysiological factors could involve in heat stress injury,such as inhibiting p hoto synt he2 sis[325];limiting sugar accumulation[6]1The adverse effect s of heat stress may be related to oxidative to cell membranes by active oxygen species[7210]1Heat st ress induced production of oxygen species inclu2 ding superoxide(O2-),hydrogen peroxide(H2O2),hydro xyl radical(O H?),and singlet oxygen (1O2)1Those free radicals are highly reactive t hat may attack and damage macromolecules such as lip2 ids,proteins,and nucleic acids in living cells[11214]1Plant s have developed enzymatic and nonenzymatic scavenging systems to quench active oxygen species1Superoxide dismutase(SOD),peroxidase(POD)

3收稿日期:2005210215

基金项目:福建省科技厅赞助项目(992Z2101)

作者简介:余高镜(19762),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　PRA TACUL TU RAL SCIENCE(Vol123,No12)2/2006 and catalase(CA T)break down to(O2-)and H2O2,respectively[8,9,13,15]1When plant s are subjected to

st ress such as high temperat ure,t he scavenging system may lo se it s f unction,and t he balance between p roducing and quenching active oxygen species can be dist urbed,resulting in oxidative damage[9,10,16]. Central to heat tolerance in plant s are cellular membrance systems which remain f unctional during heat st ress1whet her t he adverse effect s of heat st resses on different ecotypes of tall fescue involve oxida2 tive st ress which are related to changes in p rotective enzyme activity and antioxidant s have not been examined1Meanwhile a long2term solution to t he heat st ress p roblem will require develop ment of heat2tolerant cultivars,for t his p urpose,it has made great effort s in t urf grasses breeding using field se2 lection and evolution,but it appeared to be inefficient,because of unpredictable heat st ress event s and interaction wit h ot her environmental factors,typically requiring years to make effective selection1It was also to find a rapid and accurate way for measuring tall fescue heat tolerance based on t he result of our st udy1

The objective of t his st udy was:(i)to examine t he changes of five tall fescue cultivars in t urf quality,soluble sugar accumulation and root activity around t he year1(ii)to investigate changes in ac2 tivities of p rotective enzymes,plasmal membrane permeability,lipid peroxidation in five tall fescue cultivars subjected to heat st ress1

1　MATERIALS AN D METH ODS

111Plant Materials　The st udy was conducted at Fujian Agricult ure and Forestry University, Fuzhou,China,in1998—20021

Thirty2nine tall fescue varieties were int roduced f rom America for st uding bio2characteristics in t he experimental farm of Fujian Agricult ure and Forest ry U niversty respectively in September,19981 Eleven main characters including visual quality,density,text ure,color,t raffic tolerance,elasticity, growt h rate,coverage,t urf formation speed,leaf area index and tilling capacity of all varieties were recorded1Based on performance of t he eleven characters of performance,t hese varieties could be dev2 ided into five ecotypes at t he criterion514wit h t he aid of cluster analysis[17],one cultivar as t he best representive in each ecotype was selected for t his st udy,and t he file selected culutivars were G ooden, Regiment,SR28210,Brandy,and Tomahawk1

112Experiment1　The t urf grasses of each ent ry was seeded in Sep1,1998,at a rate of30g/m2,in a randomized complete block design wit h four replications1The area of each plot was2m×3m1During t he establishment,t he soil was kept moist by irrigation,t he grasses were clipped weekly at5cm height,except in summer at6cm1The grasses were evaluated in2001,t he record of air temperat ure in t he experimental farm t hroughout experiment s was in table11

Turf quality as an integral of color,uniformity,and density was rated visually on a scale of1to9 where1rep resent s brown,dormant t urf and9rep resent s t he best quality[18]1The minimum acceptable quality level was61Based on t he changes of air temperat ure in Fujian,t urf quality was tested in mid2 mont h of J an1,Mar1,May,J uly,Sep1,Nov1respectively1Root dehydrogenase activity and soluble sug2 ars were detested on t he same day1

Root activity analysised by t rip henyltet razolium chloride(T TC)met hod[19,20],t he dehydrogenase activity is related positively to respiratio n capacity,which has been used in t he st udy of t he viability of different tissues,such as seeds,leaves,and root s[19221]1To determine t he activity of root s in a sample,

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t he root s were first washed f ree of soil,and t he f resh weight was determined1Root s t hen were placed into test t ubes wit h014%(w/v)T TC in0106M Na2H PO42KH2PO4,and t he t ubes were incubated in a dark remained at37℃for3h,Sulp huric acid was added to stop t he reduction,water2insoluble red compound,formazen,formed f rom t he reduction of T TC by dehydrogenase enzymes in root s,was ex2 t racted by ground t he root s wit h et hyl acetate1The absorbance of t he ext ractant s was recorded at485 nm wit h a spect rop hotometer(Model U21100,Hitachi,Tokyo)1The reduction of T TC was analysed by compariso n to standards and t he root activity was exp ressed as t he reduced amount of T TC against root weight1

T able1　The record of air temperature in the experimental farm around the year in Fuzhou,China

Years Month Average temperature(℃)Highest temperatrue(℃)Lowest temperatrue(℃) 1999J an112151616916 Feb1141821171110

Mar1141719141210

Apr1181923181513

May221026151817

J une271431192413

J uly281533102515

Aug1281333122414

Sep1271131162317

Oct1211926161910

Nov1181924101515

Dec1141618121219

113Experiment2　This experiment was conducted to f urt her st udy t he mechanism of ecological a2 daption in t urf grasses of tall fescue exposed to different temperat ures in laboratory1The grasses were seeded in Sep1,2000,at a rate of30g/m2in15cm diameter by60cm deep polyvinylchloride(PVC) pot filled wit h soil f rom t he experimental farm as mentioned above1All t he management p ractices were t he same as experiment11

The experiment was designed in four t reat ment s of cont rolled temperat ure,wit h four replicates1 The temperat ure treat ment s were15,25,35and40℃respectively,which are based on t hat15℃was t he optimum range for t he growt h of cool2season grasses,and40℃commonly occurs in warm climatic regions during mid2summer,specially in Fuzhou,sout heast of China1The t urf grass in pot was exposed to different temperat ure treat ment s for24h,t hen t he leaves of t urfgrasses were sampled for p hysio2 chemical assay1

Cell membrane stability was estimated by measuring elect rolyte leakage(EL)1Samples of011g of f resh leaves were rinsed wit h deio nized water,t hen immersed in20mL of deionized water,and sub2 jected to a vacuum of48kPa for15min1The leaves in t ubes were shaken in flasks wit h deionized wa2 ter on a shaker table(Lab2Line Inst rument s,Inc1,Melro se Park,IL)for24h1The conductivity of t he solution(C initial)was measured using a conductivity meter(YSI Model32,Yellow Spring,O H)1 The leaves t hen were killed by autoclaving at140℃for20min1The conductivity of killed tissues (C max)was measured1Relative EL was calculated as t he percentage of C initial over C max1

To ext ract antioxidant enzymes,015g fresh leaves randomly sampled from plant s in each ent ry were ground to powder wit h liquid nit rogen in a mortar and mixed wit h8mL of50mM cool p hosp hate

78　PRA TACUL TU RAL SCIENCE(Vol123,No12)2/2006

buffer(p H710,containing1%(w/v)polyvinylpyr rolidone)1The homogenate was centrif uged at 15000x g for20min at4℃1The supernatant was used for assays of enzyme activity and lipid peroxi2 dation1

The activity of SOD was determined by measuring it s ability to inhibit t he p hotoreduction of nit ro blue tet razolium(NB T)following t he met hod of G iannopolitis and Ries[22]1The reaction solution(3 mL)contained50μM NB T,113μM ribo flavin,13mM met hionine,75nM ED TA,50mM p hosp hate buffer(p H718),and20to50μL enzyme ext ract1Test t ubes containing t he reaction solution and leaf or root samples were irradiated under a light bank(15fluorescent lamp s)at78μmol/(m2?s)for15 min1The absorbance of t he irradiated and nonirradiated solution at560nm was determined wit h a spect rop hotometer(Hitachi U21100,Tokyo,J apan)1One unit of SOD activity was defined as t he a2 mount of enzyme t hat wo uld inhibit50%of NB T p hotoreduction1

Activities of catalase(CA T)and peroxidase(POD)were measured using t he met hod of Chance and Maehly wit h modification[23]1The CA T reaction solution(3mL)co ntained50mM p hosp hate buffer(p H710),15mM H2O2,and011mL enzyme ext ract1Reaction was initiated by adding enzyme extract1Changes in absorbance of t he reaction solution at240nm were recorded every20s1One unit CA T activity was defined as an absorbance change of0101△OD value per min1The POD reaction so2 lutio n(3mL)co ntained50mM sodium acetate buffer(p H510),20mM guaiacol,40mM H2O2,and 011mL enzyme ext ract1Changes in absorbance of t he reaction solution at470nm were determined ev2 ery20s1One unit POD activity was defined as an absorbance change of0101△OD value per min1 The specific activity of each enzyme was exp ressed on a p rotein basis1Protein concent r ation of t he crude ext ract was measured by t he met hod of Bradford[24]1

The relative activity of each enzyme was exp ressed by t he activity of each enzyme in higher tem2 perat ure t reat ment over t he activity at15℃1

The lipid peroxidation level was determined in terms of malondialdehyde(MDA)content by t he met hod of Dhindsaet al1[25]1A2mL aliquot of enzyme solution was added to a t ube containing1mL 20%(v/v)t richloroacetic acid and015%(v/v)t hiobarbit uric acid1The mixt ure was heated in a water bat h at95℃for30min,cooled to room temperat ure and t hen cent rif uged at10000x g for10min1 The absorbance of supernatant at532nm was determined and t he nonspecific absorbance at600nm was subt racted1The MDA content was calculated by t he extinction coefficient of155mM/cm[26]1

2　RESU L TS

211Change of turf qu ality in year around　Turf quality in different cultivars varied wit h t he sea2 sons of a year in t he same t rend(Fig11)1It performed better in J an1,Mar and Nov1,but worse in May,J uly and Sep11The analysis of comparison among t he ent ries indicated t hat t he cultivars exhibi2 ted t heir different level of quality in t hat G ooden was t he best,and t he reverse was t ure in t he case of SR28210and A TF around t he year1In t he period from May to Sep1t he five cultivars of tall fescue un2 der consideration showed t heir different t urf quality levels in t he following order:G ooden>Regiment >To mahawk>SR28210>Brandy1

212Change of root activity　The same t rend as t urf quality was found in t he root activity of each entry(Tab2)t hat t he root activity of all cultivars was t he lowest in Sep1and t he highest in March ex2 cept t hat G ooden performed t he highest root activity in J an1and t he root activity was significantly and

2/2006草　业　科　学(第23卷2期)79　

Fig11　Turf qu ality of different in diff in

constantly higher in t he time courses except in May around t he years in Regiment and Tomahawk,in which t han were detected t hat in SR28210 and Brandy,Brandy exbihited it s t he year,suggesting t hat G ooden Regiment and Tomnhawk had t environment,The reverse was t ure in SR28210and Brandy1

　The root activity of different cultivars in different time courses3μg/(g?h)

Cultivars J an1Mar1May1J uly1Sep1Nov1

G ooden128116a111110a66136a38192a29189a47132a

Regiment84170b96148b66138a21149b17123b41189b

SR2821048110c87111c65132a9166c8136c28175c

Brandy38150d64192d40192b7142d5197d28111d Tomahawk82182b94180b66172a22119b16174b41163b

3Data in letter are the means of four replicats1Means in a column followed by the same letter are not significantly differ2 ent at5%,according to Fisher’s Protected L SD Test1

213Analysis on peroxidation in different turfgrasses exposed to temperature stress　Changes of elect rolyte leakage in t he leaves of different t urf grass cultivars exposed to different temperat ures ware showed in Tab13,it indicated t hat EL value was increased wit h t he t reat ment temperat ure in2 creasing in t he same t rend in all entries1However,EL differences at15℃and25℃treat ment condi2 tions were less p rono unced during vegetative growt h and hence t he condition of heat st ress were favor2 able for growt h and develop ment in all cultivars concerned,large differences were found among all cul2 tivars under t he higher temperat ure conditions at35℃and40℃,suggsted t hat t hey unfavor t he growt h of tall fescue1G ooden,Regiment and Tomahawk performed t he better p hysiological stat us in terms of lower EL and it s increasing rate,implying t hat t he t hree t urfgrasses could be t hought of as t he cultivars t hat are heat2tolerance in summer days because of t heir higher adaptability to heat st res2 ses1

The result also revealed t hat t he change pattern of MDA in all cultivars under different tempera2 t ures was found in t he same t rend as EL and it s increasing rate,indicating t hat G ooden,Regiment and Tomahawk had much lower level in MDA content and it s increasing rate,t he reverse was true in Brandy and SR28210under heat st resses at35～40℃(Tab4)1It f urt her confirmed t hat Brandy and SR28210were sensitive to higher temperat ure st resses,which was att ributed to higher lipid peroxida2

80　PRA TACUL TU RAL SCIENCE(Vol123,No12)2/2006

tion induced by heat stresses in t urn leading to increased MDA co ntent,consequently resulted in dam2 aged plasma membrane and enhanced EL1

T able3　Changes of E lectrolyte Leakage in the leaves of different cultivars exposed to different temperatures3%

Tempreature

G ooden

EL IR

Regiment

EL IR

SR28210

EL IR

Brandy

EL IR

Tomahawk

EL IR

15℃41645148416041434170

25℃4168018651805184419981484180813541883183 35℃618246198619526183810073191711962130712153140 40℃81979313210180971081017013216111125153195911795111　3EL=Electrolyte leakage1

　increasing rate=(electrolyte leakage in different temperature2electrolyte leakage at15℃)/electrolyte leakage at15℃1 T able4　Changes of Malondiadehyde(MDA)content in leaves of different cultivars exposed to different temperatures3

Temperature

G ooden

MDA Content

(μmol/g)

IR

(%)

Regiment

MDA Content

(μmol/g)

IR

(%)

R28210

MDA Content

(μmol/g)

IR

(%)

Brandy

MDA Content

(μmol/g)

IR

(%)

Tomahawk

MDA Content

(μmol/g)

IR

(%)

15℃131021112810188915910182

25℃16176281731510032198131472318110193121931412031124 35℃2611910111531189182171371142411364119033619128133161183 40℃3717118916345156303190671935701505510467319340100268171　3EL=Electrolyte leakage1

　increasing rate=(MDA content in different temperature-MDA content at15℃)/MDA content at15℃1

214The performance of antioxidant E nzyme R elative Activity in turf cultivar exposed to dif2 ferent temperature　Biochemical analyses indicated t hat t he antioxidant enzyme relative activities in all ent ries had a significant increase from15℃to40℃(Fig12～Fig14)and less differences in t he rela2 tive activities of antioxidant enzyme SOD and POD were found among all cultivars subjected to15～25℃conditions;however CA T performed significant differences among all cultivars in t hat t he rela2 tive enzyme activities of SR28210and Brandy were much lower t han t hat of t he ot her cultivars under t he same t reat ment temperat ure of15～25℃1There were prono unced differences in t he relative activi2 ties of t he enzyme among all ent ries exposed to25～40℃conditions,showing t hat G ooden increased much more rapidly t han t he ot hers in SOD relative activity wit h temperat ure increasing,Tomahawk and Rigment showed insignificant difference but much lower t han G ooden1The two cultivars had higher activity of SOD t han SR28210and Brandy1SR28210exhibited t he lowest activitiy of SOD(Fig 2)1Especially f rom35℃to40℃,bot h SR28210and Brandy had dramatic decrease in SOD relative ac2 tivities where t he ot hers still kept markedly increasing in t hat significant differences of SOD relative activity were found in t he ent ries,indicating t hat SOD relative activity was in t he order of G ooden> Tomahawk>Regiment>Brandy>SR282101

In terms of POD relative activity,G ooden and Regiment had much higher relative activity,where as t he ot her t hree cultivars showed insignificant difference from25℃to35℃(Fig13)1But from35℃to40℃,t he cultivars of t urf grass had a p ronounced increase in t he relative activity of POD except SR28210and Brandy in t hat G ooden had t he highest relative activity,Tomahawk performed t he activity higher and Rigement exhibited in t he3rd place especially at40℃t reat ment1

The response of CA T relative activity to temperat ure t reat ment f rom25℃to40℃at25～40℃

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was less different fro m t ho se of SOD,POD(Fig4)1Brandy showed t he highest CA T relative activity except t hat less difference was found compared wit h

G ooden and Tomahawk especially at40℃t reat2

ment,and t he activity in all cultivars increased in t he

relative activity of CA T wit h t he temperat ure in2

creasing except t hat of SR28210,which had a pro2

nounced decrease f rom35℃to40℃1

This finding suggested t hat t he t urf grass of tall

fescue,G ooden,Tomahawk and Regiment had t he

higher relative activity of antioxidant enzyme which

resulted in lower free radical content s,in t urn lead to

decreased MDA content and lower EL value ,especial2

ly in heat st ress conditions(35～40℃)1The result help s explain t he higher adaptability of t hree culti2 vars to heat st resses1

Fig2　Changes of SOD relative activity in leaves of different cultivars exposed to different temperatures3

Fig3　Changes of POD relative activity in leaves of different cultivars exposed to different temperatures3Fig4　CAT relative activity in leaves of different cultivars exposed to different temperatures

3　D ISCUSSION

The assessment of heat tolerance in five tall fescue ecotypes int roduced f rom U SA revealed signif2 icant differences in genetic potential for heat tolerance wit hin t hese species1The result s showed t hat all cultivars of tall fescue concerned declined it s t urf quality in t he period fro m May to Sep1,it sugges2 ted t hat t he t he period is t he main factor t hat affect s t he t urf quality in Fujian,China1In heat mont hs f rom May to Nov1t urf quality of five cultivars was in order:G ooden>Regiment>Tomahawk> SR28210>Brandy1

Our st udy also revealed t hat positive correlation existed between root activity and t urf quality1 t hat is,t he higher root activity and t he better t urf quality always go toget her1This finding suggested t hat root activity could be used as an important p hysiological indicator for t he evaluation of adaptabili2 ty to enviroment conditions in year around1The higher root activity is correlated wit h t he higher up2 take ability in t urfgrasses,and hence t he better t urf quality was t he result1

82　PRA TACUL TU RAL SCIENCE(Vol123,No12)2/2006

It was also indicated t hat t he root activiy of tall fescue were significantly affected by t he tempera2 t ures around t he year,and different cultivar of tall fescues different in heat-tolerance,which may be related to t he p rotective mechanism in st ress conditio ns1Plant s adopted different protective mecha2 nisms to scavenge t he f ree radicals produced under heat st ress1Antioxidant enzymes are t he mo st cru2 cial among t hem1Superoxide dismutase is t he key enzyme in t he active oxygen scavenger system be2 cause it catalyzes supero xide f ree radical dismutation into H2O2and O2[8,9,12,13]1Bot h Catalase and per2 oxidase constit ute a set of enzymes t hat catalyze t he oxidation of subst rates by H2O2,break down and detoxifies H2O2[15]1Thus,decreases in POD and CA T activity would result in H2O2accumulation, which can react wit h(O2-)to p roduce hydroxyl2free radicals via t he Herbert2Weiss reaction[8,9]1The hydroxyl-free radicals can directly damage t he membrane by attacking unsat urated fatty acids of lipid to induce lipid peroxidation[27]1

In our st udies,in t he treat ment of25～35℃all cultivars had a significant increase in relative ac2 tivity of SOD,which resulted in H2O2accumulation,in t urn induced higher activities of POD and CA T,t hen lower MDA and EL could be t he result1it appears to be a reduction of SOD relative activity only in bot h Brandy and SR28210when expo sed to heat st ressat35℃and40℃,which might be at2 t ributed to eit her decreased synt hesis or enhanced gradation of t he enzyme(Fig2),in t urn resuted in lower increasing rate of POD relative activity and reduced CA T relative activity t han t he ot her t hree cultivars(Fig3and Fig4)1It has been reported t hat t he decline in CA T relative activity was responsi2 ble for p hotoinactivation[28,29],which may lead to t he accumulation of H2O2and causes damage to cell membranes[25]1

The result also showed t hat EL value and MDA content always went toget her and increased in t he leaves of all cultivars expo sed to heat st ress,performing significantly positive correlation between in2 creasing rate of EL and t hat of MDA content(r3=019148)1It has been documented t hat malondial2 dehyde(MDA)is a p roduct of peroxidation of unsat urated fatty acids in p hosp holipids and is responsi2 ble for cell membrane damage[30]1Heat st ress increased MDA co ntent in tall fescue similar to what has been found in ot her species[31]1Reduced cell membrane stability could have resulted from lipid peroxi2 dation of membranes caused by active oxygen species[7,25,32]1It was also found t hat heat st ress de2 creased antioxident enzyme activity,and high free radical could be t he result1However it appears to be highly different in t he decreasing rate of antioxidant enzyme activity in t he t urf grass culivars con2 cerned when expo sed to stress conditions,which was att ribuded to different abilities of heat2tolerance in different cultivars1

It t herefore can be concluded t hat t he increasing rate of EL and MDA co ntent were significantly negatively related to relative activity of SOD,POD and t urf quality1G ooden had t he best t urf quality in heat st ress conditions because of EL and antioxidant enzymes,it had t he lowest EL increasing rates and t he highest SOD and POD relative activities in t he t urfgrasses of tall fescue expo sed to tempera2 t ure st ress1Regiment performed better t han Tomahawk because of lower EL increasing rate especially at35℃t reat ment,alt hough t he ot her p hysiological data showed insignificant difference1For t he same reason Brandy performed t he worst,especially in heat st ress conditions at35～40℃1 In summary,t urf quality and heat tolerance were determined by complex factors,in present st udy we observed t he differences in t urf quality and heat tolerance among t he five ecotypes of tall fescue,

2/2006草　业　科　学(第23卷2期)83　

which st rongly suggest s t hat differences in genetic potential for heat tolerance exist s wit hin t hat spe2 cies1Screening of five ecotypes will p rovide an assessment of t he extend of variation of heat tolerance and associated biochemical changes in t urf2type tall fescue1A rapid yet accurate laboratory procedure of measuring t urf grass heat tolerance can be obtained,t hrough examining t he change of EL and antiox2 idant enzymes activity1

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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

(11福建农林大学生态研究所,福建福州350002;21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PM P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:G ooden>Regiment> Tomahawk>SR28210>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