Effects of Saline Irrigation Water on Verticillium Wilt Severity and Tomato Growth

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1 Plnt Stress 29 Glol Siene Books Effets of Sline Irrigtion Wter on Vertiillium Wilt Severity nd Tomto Growth Mejd Dmi-Remdi * Hedi Ben Oun 2 Ahmed Souissi 2 Mohsen Mnsour Hyf Jnoun-Khireddine 3 Bouzid Nsroui 2 Centre Régionl des Reherhes en Hortiulture et Agriulture Biologique, 442, Chott-Mriem, Sousse, Tunisi 2 Eole Supérieure d Agriulture du Kef, 79 Le Kef, Tunisi 3 Institut Supérieur Agronomique de Chott-Mriem, 442, Chott-Mriem, Sousse, Tunisi Corresponding uthor: * dmi_rm@yhoo.fr ABSTRACT The present study desries the omined intertive effet of wter slinity nd Vertiillium dhlie on tomto, nd quntifies the effet of this ioti stress on Vertiillium wilt (VW) severity, plnt growth nd susequent yield loss. The effets of six sline levels dded to Potto Dextrose Agr (PDA) medium on the pthogen myelil growth in vitro t C ws shown to e insignifint t P. ut redued myelium density nd inresed mirosleroti prodution, ompred to the unmended ontrols, were reorded with highest NCl doses suh s 8 nd g/l. Inresing the slinity stress (2 to g of NCl/l) to inoulted v. Ventur tomto plnts enhned the severity of VW disese nd resulted in signifint inrese in lef dmge index (LDI) reorded from to 62 dys post-plnting (DPP). Moreover, LDI noted on plnts under highest slt stress (8 nd g of NCl/l) ws more thn four times higher thn the LDI reorded t g/l. Wtering plnts (inoulted or not with V. dhlie) with sline wter, from DPP until the end of the ssy (i.e., 62 DPP), negtively ffeted plnt growth: height deresed with inresing slinity. A similr effet ws noted fter inoultion with V. dhlie. The eril prt fresh nd dry weights (FW nd DW, respetively) were generlly lower s the sliniztion level inresed; these prmeters were redued y 2-7 nd 33-43% with higher slt tretments tested (8 nd g of NCl/l) ompred to the non-sline wter ( g/l), respetively. The derese in root FW nd DW rnged etween 2-73 nd 9-7% when slinity levels inresed from 2 to g of NCl/l, ompred to the ontrol plnts irrigted with non-sline wter. The fruit FW ws lso dversely ffeted y the highest NCl doses tested (8 nd g/l); it ws redued y 38 nd 72% when ompred to the non-sline tretment. Keywords: ioti stress, disese inidene, Lyopersion esulentum Mill., lef dmge, myelil growth, slt stress, yield INTRODUCTION Tomto (Lyopersion esulentum Mill.) is mjor food plnt in the world. In Tunisi, tomto is strtegi rop ultivted for fresh onsumption, proessing, nd export. However, this rop is thretened y severl prsiti miroorgnisms inluding fungi, teri nd nemtodes. The fungl speies Vertiillium dhlie, the predominnt one, V. lo-trum nd V. triorpus re involved in tomto Vertiillium wilt (VW) (Hjloui et l. 23; Jnoun- Khireddine et l. ). Under fvorle onditions nd in the sene of geneti resistne, V. dhlie nd V. lotrum were reported to e responsile for 3 to 69% of yield losses (Jones nd Crill 97). Eonomi losses used y these pthogens n reh % espeilly on tomto ultivrs severely infeted y V. dhlie (Jnoun-Khireddine et l. 27). However, lsting reent yers, severl ses of resistne rekdown were noted on mny resistnt tomto ultivrs suh s Coliri nd Riogrnde. In ft, the emergene of re 2 of V. dhlie in Tunisi ws reently reported nd ws shown to e involved in the outrek of VW symptoms on resistnt tomto ultivrs (Dmi-Remdi et l. 26). In ddition to these ioti onstrints relted to diversity nd evolution within pthogen popultions, severl other ioti ftors, suh s fertiliztion nd slinity, re involved in tomto VW development. In ft, minerl fertiliztion, vi its lne, defiieny or exess my ffet the severity of tomto vsulr diseses suh s VW (Messien et l. 99). Thus, nitrogenous fertilizers were reported to entute virulene of different Vertiillium speies. Moreover, Chernyev et l. (984) showed tht fertilizers ontining NH 4+ -N stimulte soil iologil tivity, espeilly of V. dhlie ntgonists. The effet of potssium fertilizers on redution of VW ws reported y severl uthors (Adel-Rheem nd Bird 967; Hfez et l. 97; Ashworth et l. 982). The effet of NCl on VW development hs een extensively studied. In ft, this disese, whih is normlly fvored y moderte tempertures of out 2- C (Edginton nd Wlker 97), my our under wrm onditions when the osmoti potentil of the medium deresed (Besri 98). Irrigtion with sline wter my negtively ffet not only the physil nd hemil soil properties ut lso plnt growth, prodution nd metolism leding to inresed severity of some diseses (Triky-Dotn et l. ). Intertion etween V. dhlie nd wter slinity ws studied on potto (Nhmis et l. 993) where disese expression nd oloniztion y the pthogen were more severe on ultivrs irrigted with sline wter ompred with those irrigted with fresh wter. Similrly, Levin et l. (23) reported the existene of positive synergisti intertion etween slinity nd V. dhlie ttking olive trees where disese severity ws oserved exlusively t high slt onentrtions. NCl ws shown to onsiderly ffet the inidene nd severity of tomto root nd rown rot used y F. oxysporum f. sp. rdiis-lyopersii (FORL) (Triky-Dotn et l. ) nd tomto vsulr wilt used y Fusrium oxysporum f. sp. lyopersii (FOL) (Besri 98; Dmi- Remdi et l. 29). Benyhi et l. (24) reported tht the inrese of osmoti potentil of irrigtion solution y the ddition of NCl or N 2 SO 4 enhned the development of root rot on tested rootstoks. Moreover, the osmoti pot- Reeived: 2 Otoer, 29. Aepted: Deemer, 29. Originl Reserh Pper

2 Plnt Stress 3 (), Glol Siene Books entil ws inresed y NCl, predisposing roots to intense oloniztion y Phytophthor prsiti. In Tunisi, the mjority of wter ville for plnt irrigtion is rkish (El Mhjou et l. 979; Askri 2), espeilly in ostl zones where infiltrtion of se wter uses serious slinity prolems. This sitution is more evident in the Shel region where slt onentrtion rehed 7 g/l nd % of surfe wells ville for irrigtion presented slinity level higher thn 4 g/l (Anonymous 27). Moreover, the development of griulturl tehniques in reent yers hs ontinuously umulted slt in soils nd slinity stress is eoming the mjor prolem in Tunisin griulture. The frequent use of hevy quntities of hemil fertilizers nd the overexploittion of griulturl res, espeilly in Shel regions, hs drmtilly multiplied the surfe re ffeted y slinity. Due to these elementry effets of ioti nd ioti stresses on plnts in generl nd tomto in prtiulr, we intended to ) study the in vitro tion of NCl on V. dhlie development, in prtiulr, the slinity pthogen intertion, nd 2) to eluidte the in vivo multiple effets of the triprtite omplex slinity pthogen plnt on vegettive growth nd prodution of tomto nd on VW severity. MATERIALS AND METHODS Plnt mteril Vertiillium-suseptile (ve) tomto seeds (Lyopersion esulentum Mill. v. Ventur ) used were grtefully provided y the lortory of seed nd plnt ontrol of the Generl Diretion of the Protetion nd Control of the Agriulturl Produt Qulity, Tunisi. Tomto seeds were superfiilly disinfeted y immersion in solute ethnol for 2 min nd then extensively rinsed in sterile distilled wter (SDW). Seeds were then sown in lveolus pltes filled with pet previously sterilized t 7 C during h. Seedlings were grown in greenhouse nd wtered dily until use. Experiments were performed with 4-week-old tomto plnts i.e. t the two to the three-lef stges generlly hosen for pthogen inoultion (Jnoun-Khireddine et l. 26). Pthogen V. dhlie tested in the present study ws isolted from tomto plnts showing wilt symptoms nd vsulr disolortion. Monoonidil isoltes were ultured t 2 C on PDA (potto dextrose gr) medium dded with 3 mg/l of streptomyin sulphte (Phrmdrug Prodution Gmh, Hmurg, Germny) nd their pthogeniity ws previously verified on v. Ventur tomto plnts (Dmi-Remdi et l. 26). Liquid ultures used for sustrte inoultion were prepred on PDB (potto dextrose roth) nd inuted t 2 C under ontinuous gittion t rpm during 4 to dys. The otined spore suspension ws djusted to 7 spores/ml y Mlssez ytometer. For their long-term preservtion, pthogen isoltes were stored up to 2 months t -2 C in 4% glyerol solution. Effet of different slinity levels on V. dhlie myelil growth The different quntities of NCl (i.e. doses) tested were dded to Erlenmeyer flsks ontining 2 ml of PDA, just efore pouring it in Petri dishes (dimeter 9 m), in order to modify the osmoti potentil of the medium. Agr plugs (dimeter 4 mm) of 2 dysold ultures, tken from the edges of tively growing olonies, were plted in the enter of eh treted Petri dish. The men dimeter of the pthogen olonies ws noted fter 7 dys of inution t C. These in vitro V. dhlie slinity level intertions were ompleted y severl mrosopi nd mirosopi oservtions of pthogen olonies. Sttistil nlyses were performed following ompletely rndomized design where slt tretment represented the sole fixed ftor. Five replites (five Petri pltes for eh slinity tretment) were used per slinity level nd mens were seprted using Fisher s proteted LSD test (t P.). All sttistil nlyses were performed using SPSS (Sttistil Pkge for Soil Sienes) version. Effet of different slinity levels on tomto VW severity nd plnt growth The root-dip method is used for tomto seedling inoultion. Seedlings t the two to three-lef stges were uprooted, their roots wshed with tp wter, rinsed in SDW nd dipped for 3 min in pthogen spore suspension ( 7 spores/ml). Seedlings dipped in SDW served s the uninoulted ontrol. All the seedlings were trnsplnted, immeditely fter inoultion, to pots (6 m dimeter) filled with mixture of pet nd perlite (7%: %), previously sterilized t 7 C for h, nd mintined under unheted greenhouse onditions where the temperture rnged etween 9 nd 23 C. During the first dys following inoultion, plnts were wtered regulrly with tp wter to fvor revivl following trnsplnting. Therefter, pots were wtered, every 2 dys, with wter mended or not with NCl. The dded quntity of wter ws dequte to replenish the wter level in the ulture sustrte to pots pity. Six NCl doses were tested:, 2, 4, 6, 8 nd g/l. Plnts uninoulted with V. dhlie were inluded in the experiment to provide n ssessment of the effet of the slinity on plnts in the sene of the pthogen. Five plnts were used per elementry tretment. VW severity ws estimted 62 dys post-plnting (DPP), vi the lef dmge index (LDI) nd ording to -4 sle whih depends on symptom severity on leves (Jnoun-Khireddine et l. 27). Plnt height nd LDI were reorded weekly. At the end of the ssy, the root nd stem dry nd fresh weights (DW nd FW, respetively), nd the fruit weight were noted for ll tomto plnts. Sttistil nlyses were performed, for ll mesured prmeters, following ompletely rndomized ftoril design where fungl tretments (inoulted or non with V. dhlie) nd NCl doses were the fixed ftors. Five replites per elementry tretment were used nd mens were seprted ording Fisher s proteted LSD test (t P.). RESULTS Effet of NCl on V. dhlie myelil growth in vitro The effets of six sline levels dded to PDA on the men dimeter of V. dhlie olonies, formed fter 7 dys of inution t C, ws shown to e insignifint t P.. Otherwise, pthogen olony development under diverse slt stresses is sttistilly omprle to those of the untreted ontrol fter 7 dys (Fig. ) nd dys of inution. However, some mirosopi oservtions showed tht the inresing NCl doses in the growth medium, did not negtively ffet pthogen sporultion. With highest NCl doses suh s 8 nd g/l, V. dhlie olonies showed redued eril myelium prodution nd onsequently hyphl density nd produed more mirosleroti thn the unmended ontrols (Fig. 2). Effet of NCl on tomto Vertiillium wilt severity The effets of slt stress on the intensity of lef dmge used y V. dhlie on tomto plnts were eluidted. Sine uninoulted ontrol plnts were symptomless under ll stress onditions, only dt of inoulted plnts re presented. Fig. 3 shows tht inresing NCl dose (from 2 to g/l) to inoulted tomto plnts enhned the development of VW disese nd resulted in signifint inrese in the LDI reorded from to 62 DPP. Hene, higher LDI ws noted t 8 nd g/l slinity levels (Fig. 4). At the end of the ssy i.e., 62 dys post-inoultion, the LDI reorded depended on the fungl tretment nd the NCl dose tested; signifint intertion ws noted etween oth fixed ftors t P.. Fig. shows tht ino- 4

3 Slt stress nd Vertiillium wilt. Dmi-Remdi et l. 4 Colony dimeter (m) 3, 3 2, 2,, NCl dose (g/l) Fig. Effet of different NCl-sed tretments on V. dhlie rdil growth noted on PDA fter 7 dys of inution t C. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). g/l 2 g/l 4 g/l 6 g/l 8 g/l g/l Control V. dhlie Fig. 2 Effet of different NCl-sed tretments on V. dhlie myelil growth nd mirosleroti undne on PDA noted fter 7 dys of inution t C. Fig. 4 Disese severity of tomto v. Ventur plnts inoulted with V. dhlie nd wtered with sline wter ( g of NCl/l), ompred with uninoulted ontrol reorded 6 dys post-plnting. dys 42 dys 49 dys 6 dys 62 dys,8,6,4 Lef dmge index,2,8,6,4, NCl dose (g/l) Fig. 3 Effet of inresing wter slinity on the disese severity of tomto v. Ventur plnts inoulted with V. dhlie reorded to 62 dys post-plnting. ulted plnts wtered with inresing wter slinity signifintly enhned wilt severity ompred to plnts wtered with non-sline wter. LDI on plnts under highest slt stress (8 nd g of NCl/l) ws more thn four times higher thn tht reorded t g/l. NCl doses suh s 2, 4 nd 6 g/l used signifint inrese in LDI ompred to the unstressed ontrol. Effet of NCl on tomto growth nd prodution. Plnt height Plnt height inrese, from to 62 DPP, ws relted to NCl dose nd fungl tretment, independently, s intertion etween oth fixed ftors ws sttistilly insignifint. In ft, slinity tretment in wtering v. Ventur tomto plnts from DPP until the end of the ssy neg- 42

4 Plnt Stress 3 (), Glol Siene Books 2, 2 Lef dmge index,, NCl dose (g/l) Fig. Effet of inresing wter slinity on the disese severity of tomto v. Ventur plnts inoulted with V. dhlie reorded 62 dys postplnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). Plnt height (m) dys 42 dys 49 dys 6 dys 62 dys NCl dose (g/l) Fig. 6 Effet of inresing wter slinity on the plnt height of tomto v. Ventur plnts reorded to 62 dys post-plnting. For eh reorded dte (i.e dys post-plnting), rs (for NCl doses) with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). Plnt height (m) dys 42 dys 49 dys 6 dys 62 dys Control Fungl tretment V. dhlie Fig. 7 Plnt height of tomto v. Ventur plnts inoulted or non with V. dhlie reorded to 62 dys post-plnting. For eh reorded dte (i.e dys post-plnting), rs (for fungl tretments) with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). tively ffeted plnt growth s height deresed with inresing slinity level (Fig. 6). The inrese in plnt height over time ws gretest in the se of plnts irrigted with non-sline wter. In ontrst, under highest slt tretments (8 nd g of NCl/l), plnt growth ws strongly redued ompred to unstressed plnts ( g/l). The rte of inrese in plnt height, whih ws relted to the fungl tretment, slowed down on inoulted plnts ompred with the uninoulted ontrol (Fig. 7). The sme oservtion ws noted with sline wter irrigtion. Plnt height, noted t 62 DPP, depended signifintly (t P.) on NCl dose (Fig. 8). The derese in this growth prmeter vried etween nd % when NCl dose inresed from 2 to g/l. Also, plnt height deresed fter inoultion y the fungus (out 7% less tht the uninoulted ontrol, Fig. 9). 43

5 Slt stress nd Vertiillium wilt. Dmi-Remdi et l. 4 4 Plnt height (m) NCl dose (g/l) Fig. 8 Effet of inresing wter slinity on the plnt height of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). Plnt height (m) Aeril prt weight Control Fungl tretment The eril prt FW nd DW, noted 62 DPP, depended signifintly (t P.) on slinity levels tested only s fungl tretments were shown to hve n insignifint effet on oth these growth prmeters. Dt presented in Fig. shows tht slinity dversely ffeted the vegettive growth of v. Ventur tomto V. dhlie Fig. 9 Plnt height of tomto v. Ventur plnts inoulted or non with V. dhlie, reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). plnts. The eril prt FW ws generlly lowered s sliniztion level inresed; this prmeter ws redued y more thn % with higher slt tretments tested (8 nd g of NCl/l) ompred to the non-sline wter ( g/l). Similrly, the eril prt DW ws lso negtively ffeted y inresing slinity levels (Fig. ) nd the redution, ompred to the ontrol plnts wtered with unslinized wter, rnged etween 9 nd 43% when NCl dose vried from 2 to g/l. 3. Root weight The root FW nd DW, noted 62 DPP, were signifintly relted (t P.) to the slinity level nd fungl tretment, independently. The intertion etween oth fixed ftors ws sttistilly insignifint. In ft, for ll slt tretment doses, the root FW nd DW inresed out 28% on inoulted tomto plnts ompred to uninoulted ones. However, under slt stress, oth these prmeters deresed when NCl doses inrese. The redution rnged etween 2 nd 73% (Fig. 2) for root FW when slinity levels inresed from 2 to g of NCl/l, ompred to the ontrol plnts irrigted with nonsline wter. Signifint dereses, ompred to the ontrol, were reorded with the 4, 6, 8 nd g/l slt tretments. However, dt presented in Fig. 3 shows tht the root DW deresed y 9 to 7% when NCl dose vried from 2 to g/l, respetively. A signifint negtive effet, ompred to the unstressed ontrol, ws otined with 6, 8 nd g/l slt tretments. 6 Aeril prt fresh weight (g) NCl dose (g/l) Fig. Effet of inresing wter slinity on the eril prt fresh weight of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). 44

6 Plnt Stress 3 (), Glol Siene Books 8 Aeril prt dry weight (g) NCl dose (g/l) Fig. Effet of inresing wter slinity on the eril prt dry weight of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). 2 Root fresh weight (g) NCl dose (g/l) Fig. 2 Effet of inresing wter slinity on the root fresh weight of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). 3 Root dry weight (g) 2, 2,, NCl dose (g/l) Fig. 3 Effet of inresing wter slinity on the root dry weight of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). 4. Fruit weight The fruit FW, noted 62 DPP, depended signifintly (P.) only on the slinity level. In ft, s shown in Fig. 4, this prmeter ws dversely ffeted y the highest NCl doses tested (8 nd g/l); it ws redued y 38 nd 72% when ompred to non-sline wter. The redution reorded with less thn 8 g of NCl/l vried etween 2 nd 28%, ut ws not sttistilly signifint. 4

7 Slt stress nd Vertiillium wilt. Dmi-Remdi et l. 4 4 Fruit fresh weight (g) NCl dose (g/l) Fig. 4 Effet of inresing wter slinity on the fruit fresh weight of tomto v. Ventur plnts reorded 62 dys post-plnting. Brs with the sme letter re not signifintly different ording to Fisher's proteted lest signifint differene LSD test (P.). DISCUSSION Two dedes go, third of ll irrigted lnds in the world were ffeted to greter or lesser degree y slinity (Psternk 987) whih hs eome urrently one of the most severe ioti ftors limiting griulturl prodution. Tomto is onsidered to e modertely sensitive to slinity (Ayers nd Westot 98; Kterji et l. 2) ut is dversely ffeted y irrigtion with sline wter t levels exeeding.7 g/l (i.e. 2. ds/m) of totl slts (Mss 986; Curtero nd Fernández-Mu oz 999). This nd higher levels re evident in mny surfe wells in ostl Tunisin regions where tomto is intensively ultured under greenhouse or field onditions (Askri 2). In ddition to this ioti stress, tomto hs een shown to e severely ffeted y mny soil-orne pthogens under sline onditions suh s FORL (Woltz et l. 992; Jones et l. 993; Triky- Dotn et l. ), FOL (Besri 98; Dmi-Remdi et l. 29), V. dhlie (Besri 98; 98; Regrgui et l. 23), nd Phytophthor prsiti (Snpp et l. 99). Intertions etween plnts, nutrients, nd disese pthogens re very omplex nd not ompletely understood. Work reported in the present study is the first desriing the omined intertive effet of wter slinity nd V. dhlie on tomto v. Ventur, nd quntifying the effet of this ioti stress on VW severity, plnt growth nd susequent yield loss. Thus, this study provides dditionl informtion on VW epidemiology under onditions of slinity stress when suseptile ultivrs were used. The pthogen slinity intertion ws evluted in vitro. Although the rdil olony growth did not tke into ount hnges in hyphl density or speifi growth rte s mentioned y Suro et l. (993), it is usully relile prmeter to mesure the effet of n environmentl vrile on the fungi growth. Moreover, Cook (973) mentioned tht this kind of in vitro experiments my reflet the pthogen ehvior in vivo, inside plnt tissues. The present results showed tht the different slinity levels tested did not negtively ffet V. dhlie rdil growth. Severl pthogens other thn V. dhlie were reported to e tolernt to slts in ulture, inluding Aspergillus, Peniillium nd Fusrium spp. (Tresner nd Hyes 97), Pythium phnidermtum (Rsmussen nd Stnghellini 988), Phytophthor spp. (MDonld 982; Blker nd MDonld 98), Fusrium oxysporum f. sp. lyopersii (Besri 98; Dmi-Remdi et l. 29), nd F. oxysporum f. sp. vsinfetum (Rgzzi nd Vehio 992). However, NCl ws shown to use greter redutions of in vitro growth of hrol rot usl gent thn KCl or surose. NCl used the gretest negtive effets on Mrophomin phseolin development, morphology nd slerotiniztion due to redued pigment synthesis nd inresed eril myelium prodution (Cervntes-Grí et l. 23). The in vitro slinity V. dhlie intertion studies, reported in the present work, showed insignifint effet of slt tretments tested on pthogen sporultion nd n importnt inrese in resting strutures formtion under higher slinity levels ssoited with slight redution in hyphl density. Thus, the intertion of pthogens with slinity seemed to e quite speifi, omplex nd n not e extrpolted for ll soil-orne fungi even if they oupied the sme eologil nihe nd re sumitted to the sme ioti stress. The slinity V. dhlie intertion studies on tomto v. Ventur showed tht plnts inoulted with V. dhlie nd wtered with inresed sline wter onentrtions were severely ffeted y VW. This finding is in ordne with previous reports on V. dhlie: Besri (99), Livesu et l. (99) nd Nhmis et l. (993). In ft, the intertion etween V. dhlie nd sline irrigtion wter ws oserved on potto where disese expression nd oloniztion levels of the fungus were found to e more severe in V. dhlie-tolernt ultivrs irrigted with sline wter ompred with plots irrigted with fresh wter (Nhmis et l. 993). In the sme wy, V. lo-trum hs een isolted from lflf growing in region of the Mojve desert of Cliforni (Erwin et l. 988, 989) where soil slinity is typilly high (Bklund nd Hoppes 984). Experimentlly, the ddition of slinity stress (3. or. ds/m) to inoulted NK lflf plnts enhned the progression of VW disese (Howell et l. 994). Soil exposed to slinity hs een lso reported to inrese the suseptiility of some rops to soil-orne fungi suh s Phytophthor spp. (MDonld 982; Blker nd MDonld 986; Bouhii et l. 99; Snpp et l. 99; Snogo 24), Pythium ultimum (Mrtin nd Hnok 98), FOL (Dmi-Remdi et l. 29) nd FORL (Woltz et l. 992; Jones et l. 993). The inidene nd severity of rown nd root rot disese of tomto inresed signifintly under irrigtion with sline wter; the pthogen uild-up t the root zone in soil ws fster, the disese onset me erlier, nd yield ws signifintly redued (Triky-Dotn et l. ). Moreover, slinity stress my weken the geneti resistne of plnts to disese y induing hnges in suseptiility of root tissue to pthogen onentrtion (MDonld et l. 984). The present results showed tht the mjority of growth prmeters, i.e., plnt height, eril prt nd root FW nd DW were negtively ffeted y wter slinity levels. Only the highest NCl onentrtions ffeted ll of the onsidered prmeters nd used signifint redution in root nd shoot growth. These findings equls tht of severl uthors who found tht slinity dversely ffeted the vegettive growth of tomto, nd it redued plnt length nd 46

8 Plnt Stress 3 (), Glol Siene Books DW (Adler nd Wilor 987) nd lso the FW nd DW of shoots nd roots (Omr et l. 982; Shnnon et l. 987; Hjer et l. 26; Dmi-Remdi et l. 29). Inresing NCl onentrtion in nutrient solution dversely ffeted tomto shoot nd roots, nd plnt height (Al-Krki 2). Furthermore, the lef nd stem DWs of tomto were lso signifintly redued in plnts irrigted with sline nutrient solution in ontrst with ontrol plnts (Stti nd Al-Yhyi 99). Redution of DWs due to inresed slinity my e result of omintion of osmoti nd speifi ion effets of Cl nd N (Al-Rwhy 989). These growth prmeters were redued y more thn % with higher slt tretments i.e., 8 nd g/l doses tested. Thus, ultivtion of suseptile tomto ultivrs suh s v. Ventur my led to inresed plnt growth inhiition ssoited with inresed VW severity. Moreover, the fruit FW ws dversely ffeted y higher NCl doses tested (8 nd g/l); it ws redued y 38 nd 72% ompred to non-sline wter. Similrly, greter yield losses were used y slinity stress sumitted to tomto v. Ventur plnts infested with FOL nd lflf plnts lredy inoulted with V. lo-trum (Howell et l. 994; Dmi-Remdi et l. 29). In the sme wy, the use of sline wter for irrigtion inreses the slt onentrtion in the soil nd therey ffets plnt development y reduing plnt growth, yield, nd qulity (Akiln et l. 997). The effet of slinity on plnt disese my result from its effet on one or more ioti omponents involved in the disese: the pthogen, the host resistne or suseptiility, the miroil tivity in the soil, or the ioti omponents of the soil (Triky-Dotn et l. ). In ft, inresing slt in the root zone indues osmoti hnges nd interferes with nutrient uptke (Cornillon nd Plloix 997; Hlperin et l. 23). Nutrient imlnes resulted from the effet of slinity on nutrient vilility, ompetitive uptke, trnsport or prtitioning within the plnt (Grttn nd Grieve 994). Moreover, irrigtion wter ontining NCl ontriutes to the diret effets of exess slt on plnt growth tht my e desried s n osmoti stress, reduing wter vilility; ion imlne stress, used y ntgonisti effets on nutrient elements; nd speifi toxiity of Cl-, N+, or oth (Víllor et l. 2). Our findings onerning the intertion of VW disese of tomto with slinity orrespond to studies in similr or different pthosystems nd indited tht the use of even lower slinity wters (s is the se of the dose 4 g/l nd to lesser degree 2 g/l) n ffet plnt helth nd growth. Moreover, sed on this pot experiment, it is possile tht for tomto ultivrs growing in res where wter slinity lredy uses prolem, n inrese in suseptiility to VW n mplify the yield redution more. Consequently, n effetive mngement of V. dhlie in fields with high level of slinity should inlude, in the future, the seletion of resistnt ultivrs with tolerne to slinity for limiting eventul yield losses due to onomitnt ioti nd ioti stresses. However, further studies on omprtive ehvior of ville resistnt nd suseptile tomto ultivrs under slt stress re needed to e plnned firstly. ACKNOWLEDGEMENTS Authors thnk the Regionl Center of Reserh in Hortiulture nd Orgni Agriulture (CRRHAB) for finnil ontriution, nd Mrs. Moun Gueddess-Chhed nd Mr. Aymen Youssef for tehnil ssistne. REFERENCES Adel-Rheem A, Bird LS (967) Effet of nutrition on resistne nd suseptiility of otton to Vertiillium lo-trum nd Fusrium oxysporum f. vsinfetum. Phytopthology 7, 47 Adler PR, Wilor GE (987) Slt stress, mehnil stress, or Chloromequt hloride effets on morphology nd growth reovery of hydroponi tomto trnsplnts. Journl of the Amerin Soiety for Hortiulturl Siene 2, 22- Akiln K, Frrell RCC, Bell DT, Mrshll JK (997) Responses of lonl river red gum (Eulyptus mldulensis) to wter logging y fresh nd slt wter. Austrlin Journl of Experimentl Agriulture 37, Al-Krki GN (2) Growth, wter use effiieny, nd sodium nd potssium quisition y tomto ultivrs grown under slt stress. Journl of Plnt Nutrition 23, -8 Al-Rwhy SA (989) Nitrogen uptke, growth rte nd yield of tomtoes under sline ondition. PhD thesis, University of Arizon, Tuson, 8 pp Anonymous (27) Dignosti, suivi et exploittion des zones irriguées. Rpport du ommissrit régionl de développement griole de Monstir, pp (internl report) Ashworth LJ, Morgn DP, Gon SA, MCin AH (982) Polyethylene trping ontrols Vertiillium wilt in pisthios. Cliforni Agriulture 36, 7-8 Askri H (2) Utilistion des eux et des sols slés en Tunisie. In : FAO (Ed) Atelier sur l prolémtique du suivi et de l évlution de l slinité et de l fertilité des terres irriguées dns les pys du Mghre orgnisé à Alger (Algérie), Jnury, 2, 4 pp Ayers RS, Westot DW (98) Wter Qulity for Agriulture, Irrigtion nd dringe pper 29, FAO, Rome, 74 pp Benyhi H, Mouloud MAH, Jrifi A, Lmsettef Y (24) Effet de l slinité de l'eu d'irrigtion sur l olonistion des rines des porte-greffes d'grumes pr Phytophthor prsiti. Fruits 9, -8 Besri M (98) Influene du potentiel osmotique de l'eu sur l roissne de Fusrium oxysporum f. sp. lyopersii et de Vertiillium dhlie. Phytopthologishe Zeitshrift 99, -8 Besri M (98) Qulité des sols et des eux d irrigtion et mnifesttion des trhéomyoses de l tomte u Mro. Phytopthologi Mediterrne 2, 7- Besri M (99) Effets of slinity on the development of tomto Vertiillium wilt in Moroo. In: Proeedings of the th Interntionl Symposium on Vertiillium Wilt, -3 June 99, St. Petersurg, Russi, p 6 (Astrt) Blker NS, MDonld JD (98) Effet of soil slinity on the forming of sporngi nd zoospores y three isoltes of Phytophthor. Phytopthology 7, Blker NS, MDonld JD (986) The role of slinity in the development of Phytophthor root rot of itrus. Phytopthology 76, Bouhii N, vn Bruggen AHC, MDonld JD (99) Effet of ion onentrtion nd sodium:lium rtio of nutrient solution on Phytophthor root rot of tomto nd zoospore motility nd viility of Phytophthor prsiti. Phytopthology 8, Cervntes-Grí D, Súl Pdill- Rmírez J, Simpson J, Myek-Pérez N (23) Osmoti potentil effets on in vitro growth, morphology nd pthogeniity of Mrophomin phseolin. Journl of Phytopthology, Chernyyev II, Hsnov FS, Muromtsev GS (984) Effet of vrious nitrogen forms upon Vertiillium dhlie nd the metolism of some soil teri. In: Szeji J (Ed) Soil Biology nd Conservtion of the Biosphere, Ademii Kido, Budpest, pp 73-7 Cook RJ (973) Influene of low plnt nd soil wter potentils on diseses used y soilorne fungi. Phytopthology 63, 4-48 Cornillon P, Plloix A (997) Influene of sodium hloride on the growth nd minerl nutrition of pepper ultivrs. Journl of Plnt Nutrition 2, 8-94 Curtero J, Fernández-Mu oz R (999) Tomto nd slinity. Sienti Hortiulture 78, 83- Dmi-Remdi M, Jnoun-Khireddine H, Brr DJ, Ayed F, El Mhjou M (26) First report of Vertiillium dhlie re 2 in Tunisi. Plnt Pthology, 86 Dmi-Remdi M, Souissi A, Ben Oun H, Mnsour M, Nsroui B (29) Slinity effets on Fusrium wilt severity nd tomto growth. Dynmi Soil, Dynmi Plnt 3, 6-69 Edgington LY, Wlker JC (97) Influene of soil ir temperture on Vertiillium wilt on tomto. Phytopthology 47, El Mhjou M, Bouzidi A, Jouhri A, Hmrouni A, El Beji M (979) Influene de l slinité des eux d irrigtion sur l sensiilité du tournesol u Mrophomin phseoli (Mul.) Ashy. Annles de Phytopthologie, 6-67 Erwin DC, Khn RA, Bmeur A (988) Vertiillium wilt of lflf in southern Cliforni used y Vertiillium lotrum. Plnt Disese 2, 43 (Astrt) Erwin DC, Khn RA, Howell AB, Bmeur A, Odoff S (989) Vertiillium wilt found in southern Cliforni lflf. Cliforni Agriulture 43, 2-4 Grttn SR, Grieve CM (994) Minerl nutrient quisition nd response y plnts grown in sline environments. In: Pessrkli M (Ed) Hndook of Plnt nd Crop Stress, Mrel Dekker, New York, pp Hfez AAR, Stout PR, DeVy JE (97) Potssium uptke y otton in reltion to Vertiillium wilt. Agronomy Journl 67, 9-36 Hjer AS, Mliri AA, Al-Zhrni HS, Almghri OA (26) Responses of three tomto ultivrs to se wter slinity. Effet of slinity on the seedling growth. Afrin Journl of Biotehnology, 8-86 Hjloui MR, Grgouri S, Guermeh A, Hmz N (23) Emergene en Tunisie d un nouveu pthotype de Vertiillium lo-trum pouvnt ttquer les ultivrs de tomte possédnt le gène de résistne Ve. Bulletin OEPP/ 47

9 Slt stress nd Vertiillium wilt. Dmi-Remdi et l. EPPO 33, Hlperin ST, Gilroy S, Lynh JP (23) Sodium hloride redues growth nd ytosoli lium, ut does not ffet ytosoli ph, in root hirs of Aridopsis thlin L. Journl of Experimentl Botny 4, Howell AB, Frnois L, Erwin DC (994) Intertive effets of slinity nd Vertiillium lo-trum on Vertiillium wilt disese severity nd yield of two lflf ultivrs. Field Crop Reserh 37, 247- Jnoun-Khireddine H, Dmi-Remdi M, Ayed F, Jeri H, El Mhjou M (27) Inidene of Vertiillium wilt of melon in Tunisi. The Afrin Journl of Plnt Siene nd Biotehnology, - Jnoun-Khireddine H, Dmi-Remdi M, El Mhjou M () Emergene en Tunisie de nouveux pthotypes de Vertiillium triorpus pouvnt ttquer l tomte, l uergine et l pomme de terre. Bulletin EOPP/OEPP, Jnoun-Khireddine H, Dmi-Remdi M, Hir K, Ayed F, El Mhjou M (26) Pthogeniity of Tunisin isoltes of three Vertiillium speies on tomto nd eggplnt. Plnt Pthology Journl, Jones JP, Crill P (97) Retion of resistnt, tolernt nd suseptile tomto vrieties to Vertiillium wilt. Plnt Disese Reporter 9, 3-6 Jones JP, Jones JB, Woltz SS, Sott JW (993) Influene of soil ph, nitrogen soure, nd trnsplnt drenhes on development of rown rot of tomto. Proeedings of the Florid Stte Hortiulturl Soiety 6, 7-72 Kterji N, vn Hoorn JW, Hmdy A, Mstrorilli M (2) Slt tolerne lssifition of rops ording to soil slinity nd to wter stress dy index. Agriulturl Wter Mngement 43, 99-9 Levin AG, Lvee S, Tsror (Lhkim L) (23) Epidemiology of Vertiillium dhlie on olive (v. Piul) nd its effet on yield under sline onditions. Plnt Pthology 2, Livesu L, Kufmn Z, Nhmis A (99) The effet of slinity on Vertiillium wilt of potto. In: Proeedings of the th Interntionl Symposium on Vertiillium Wilt, -3 June 99, St. Petersurg, Russi, p 9 (Astrt) MDonld JD (982) Effet of slinity stress on the development of Phytophthor root rot of hrysnthemum. Phytopthology 72, MDonld JD (984) Slinity effets on the suseptiility of hrysnthemum roots to Phytophthor ryptoge. Phytopthology 74, Mrtin FN, Hnok JG (98) Reltionship etween soil slinity nd popultion density of Pythium ultimum in the Sn Joquin Vlley of Cliforni. Phytopthology 7, 893 (Astrt) Mss EV (986) Slt tolerne of plnts. Applied Agriulturl Reserh, 2-26 Messien C-M, Blnrd D, Rouxel F, Lfon R (99) Les Mldies des Plntes Mrîhères (3 rd Edn), INRA, 68 pp Nhmis A, Kufmn Z, Livesu L, Tsror L, Meiri A, Cligri PDS (993) Effet of slinity nd its intertion with disese inidene on pottoes grown in hot limtes. Phytoprsiti 2, 24- Omr MA, Omr FA, Smrri SM (982) Effet of different soil tretments on tomto plnts grown in Wdi Ftim soil. B. Effet of slinity tretments. Tehnil Report, Fulty of Meteorology, Environment nd Arid Lnd Agriulture, Sudi Ari, 26 pp Psternk D (987) Slt tolerne nd rop prodution: A omprehensive pproh. Annul Review of Phytopthology, Rgzzi A, Vehio V (992) Behviour of hlmydospore of Fusrium oxysporum f. sp. vsinfetum in sustrtes ontining sodium hloride. Phytopthologi Mediterrne 3, 8-87 Rsmussen SL, Stnghellini ME (988) Effet of slinity stress on development of Pythium light in Agrostis plustris. Phytopthology 78, Regrgui A, Rhouti M, Lhlou H (23) Effet du stress slin sur Vertiillium lotrum: pthogénéité et prodution d enzymes ellulolytiques in vitro. Cryptogmie Myologie 24, Snogo S (24) Response of hile pepper to Phytophthor psii in reltion to soil slinity. Plnt Disese 88, -29 Stti SM, Al-Yhyi RA (99) Slinity tolerne in tomto: Implitions of potssium, lium nd phosphorus. Soil Siene nd Plnt Anlysis 26, Shnnon MC, Gronwld JW, Tl M (987) Effet of slinity on growth nd umultion of orgni nd inorgni ions in ultivted nd wild tomto speies. Journl of the Amerin Soiety for Hortiulturl Siene 2, 6-23 Snpp SS, Shermn C, vn Bruggen AHC (99) Effets of slinity on severity of infetion y Phytophthor prsiti Dst., ion onentrtions nd growth of tomto, Lyopersion esulentum Mill. New Phytologist 9, Suro KV, Mihilides TJ, Morgn DP (993) Effets of osmoti potentil nd temperture on growth of two pthogens of figs nd ioontrol gent. Phytopthology 83, Tresner HD, Hyes JA (97) Sodium hloride tolerne of terrestril fungi. Applied Miroiology 22, 2-23 Triky-Dotn S, Yermiyhu U, Ktn J, Gmliel A () Development of rown nd root rot disese of tomto under irrigtion with sline wter. Phytopthology 9, Víllor G, Moreno DA, Pulgr G, Romero L (2) Yield improvement in zuhini under slt stress: determining mironutrient lne. Sienti Hortiulture 86, 7-83 Woltz SS, Jones JP, Sott JW (992) Sodium hloride, nitrogen soure, nd lime influene Fusrium rown rot severity in tomto. HortSiene 27,