Net melon resistance to Didymella bryoniae according to grafting and potassium levels

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1 Net melon resistnce to Didymell ryonie ccording to grfting nd potssium levels Edvr de Sous d Silv 1 ; Felipe Cmpner Plngn 1 ; Rumy Goto 1 ; Edson Luiz Furtdo 1 ; Dirceu Mximino Fernndes 1 1 UNESP/Fculdde de Ciêncis Agronômics/Depto. Produção Vegetl, Ru José Bros de Brros, 1780, C. postl 237, , Botuctu- SP, Brsil. Autor pr correspondênci: Edvr de Sous d Silv (edvrdesous@yhoo.com.r) Dt de chegd: 02/08/2011. Aceito pr pulicção em: 13/02/ ABSTRACT Silv, E.S.; Plngn, F.C.; Goto, R.; Furtdo, E.L.; Fernndes, D.M. Net melon resistnce to Didymell ryonie ccording to grfting nd potssium levels. Summ Phytopthologic, v.38, n.2, p , Chemicl control of the fungus Didymell ryonie, the cusl gent of the disese gummy stem light in melon, is frequently inefficient; thus, lterntives such s grfting nd nutrition must e studied. Rootstocks nd potssium levels were tested imed t controlling this disese in net melon under protected environment. The melon hyrid Bônus II, ungrfted nd grfted onto Dinero melon nd Strong Tos pumpkin rootstocks, ws cultivted nd inoculted y using the toothpick insertion method with 7-mm mycelil disks from the isolte D. ryonie Dr 37; for control, only toothpick insertion ws used. The plnts were sujected to the following potssium levels: 0, 62.5, 125, 187.5, 250 mg L -1. Grfted Bônus II melon plnts were resistnt to the fungus, wheres ungrfted ones were susceptile. The dopted potssium levels did not influence the stem lesion size or the survivl of plnts. Additionl keywords: Cucumis melo vr. reticultus Nud., gummy stem light, nutrition, rootstock. RESUMO Silv, E.S.; Plngn, F.C.; Goto, R.; Furtdo, E.L.; Fernndes, D.M. Resistênci de meloeiro rendilhdo à Didymell ryonie em função d enxerti e concentrções de potássio. Summ Phytopthologic, v.38, n.2, p , O controle químico do fungo Didymell ryonie, gente cusl d doenç crestmento gomoso em meloeiro, frequentemente é ineficiente, e lterntivs como enxerti e nutrição devem ser estudds. Portenxertos e concentrções de potássio form testds ojetivndo controlr doenç est doenç em meloeiro rendilhdo, so miente protegido. O hírido de meloeiro Bônus II pé-frnco e enxertdo em port-enxertos melão Dinero e óor Strong Tos form cultivdos e inoculdos pelo método de inserção de plito com discos de micélio de 7 mm do isoldo de D. ryonie Dr 37, e o controle somente com inserção do plito. As plnts form sumetids às concentrções de potássio 0; 62,5; 125; 187,5; 250 mg L -1. Plnts de meloeiro Bônus II enxertds form resistentes o fungo e s não enxertds suscetíveis. As concentrções de potássio não influencirm tnto no tmnho d lesão no cule qunto n sorevivênci ds plnts. Plvrs-chve dicionis: Cucumis melo vr. reticultus Nud., crestmento gomoso, nutrição, port-enxerto. One of the most importnt diseses ffecting net melon (Cucumis melo vr. reticultes Nud.) in protected environment is gummy stem light or stem cnker, which is cused y the fungus Didymell ryonie (12). Chemicl control hs frequently shown low efficiency; however, some lterntives hve een successful, such s grfting onto rootstocks of resistnt melons, disinfection of pruning shers, estlishment of the protected environment in plces other thn lowlnds, crop rottion, nd rtionl irrigtion control (2, 10, 12 nd 15). The use of grfting for vegetles such s pepper, tomto, eggplnt, cucumer nd melon cultures hs llowed the solution of prolems relted to soil pthogens. According to Trionfetti-Nisini et l. (12) nd Crino et l. (3), this technique cn e n lterntive to control the fungus D. ryonie, which is not considered soil plnt ut cn survive in plnt deris in the soil. This lterntive ws lso proven y Ito et l. (4), who tested severl rootstocks nd concluded tht Benincs hispid ws highly resistnt to D. ryonie nd most recommended s rootstock for net melon. Another lterntive to control diseses in plnts hs een minerl nutrition preprtion; however, the interction etween nutrition nd diseses hs een scrcely studied, frequently yielding contrdictory results or misinterprettions. On the other hnd, the importnce of nutrition on the mnifesttion or not of diseses is well known (13). The effect of nutrition on the intensity of diseses is known for certin numer of plnts cultivted under controlled condition, ut there re few studies relted to the melon culture, especilly the net type. This study imed to ssess net melon resistnce to D. ryonie ccording to grfting nd potssium levels. Summ Phytopthol., Botuctu, v. 38, n. 2, p ,

2 MATERIAL AND METHODS The experiment ws crried out t the Experimentl Frm of Teching, Reserch nd Production elonging to the School of Agronomicl Sciences (FCA) of UNESP-Universidde Estdul Pulist (22 o 44 S, 48 o 34 W; round 750 m ltitude; mesotherml climte type, humid sutropicl Cf). Pots were kept under protected environment, in 10x40m rch-type structure covered with trnsprent 100µm-thick low-density polyethylene (LDPE) film, from My to Septemer Experimentl design ws in rndomized locks, in 3x5 fctoril rrngement: Bônus II hyrid melon plnts grfted onto Dinero melon nd Strong Tos pumpkin rootstocks, ungrfted Bônus II, nd five potssium levels: 0, 62.5, 125, 187.5, 250 mg L -1, totling 15 tretments. The potssium levels 0, 62.5, 125, nd 250 mg L -1 represent, respectively, 0%, 50% elow the recommended level, the recommended level, 50% ove the recommended level nd 100% ove the recommended level ccording to Kno (5) nd were supplied s potssium nitrte. In ech plot, net melon plnts (Cucumis melo vr. reticultus Nud.), Bônus II hyrid, grfted nd ungrfted, were cultivted in row spced t 1.0 x 0.50 m, totling 12 plnts per plot; six useful plnts nd two plnts t ech tretment extreme of plot served s order. Before inocultion, D. ryonie isoltes were cultured in PDA (potto dextrose gr) medium utoclved t 120 C for 20 min t 1.5 tm. For ech Petri dish contining 20 ml culture medium, three mycelil disks of 7mm dimeter were recultured during seven dys t 20 ºC in the drk. Inocultion ws done t 20 dys fter trnsplnt y the toothpick method, inserting 7mm pthogen mycelil disks into the stem previously injured y toothpick, dpted from Trionfetti- Nisini et l. (12). Inoculted plnts were kept in humid chmer for 12 h; they were lso spryed with wter nd covered with plstic ottles. Evlutions strted t seven dys fter the inocultion of isoltes nd continued t every seven dys from then. The symptoms were quntified y mesuring the longitudinl nd the trnsversl length of necrosis resulting from pthogen coloniztion. The disese intensity in ech plnt ws the result of the simple rithmetic men etween the two dimensions, constituting the men dimeter of the lesion. Dt were sujected to fctoril nlysis of vrince (F test) t 5% proility, nd Tukey s test t 5% proility ws used to compre mens. RESULTS AND DISCUSSION During the experimentl period, the mximum temperture rnged from 17.7 to 43.9 C nd the minimum temperture from 4.5 to 18.3 C (Figure 1). As regrds the lesion men dimeter, only the mens of grfted plnts were compred (Tle 1 nd Figure 2) due to the erly nd high mortlity of ungrfted plnts. The ltter were compred to grfted plnts considering the percentge of plnt survivl (Tle 2 nd Figure 3). The min effect of the fctor plnt type ws significnt in ll evlutions nd non-significnt for potssium levels nd interction etween the two fctors on the lesion men dimeter (Tle 1) nd plnt survivl (Tle 2). Bônus II plnts grfted onto Dinero melon rootstock hd lrger lesion men dimeter in ll evlutions, gretly differing from plnts grfted onto Strong Tos pumpkin rootstock, reching 3.79 cm t 56 DAI (Dys fter inocultion) (Figure 2). For ll plnts in which the rootstock Strong Tos ws used, the lesion lmost did not develop, keeping limited to the rootstock region; the lrgest lesion men dimeter in these plnts ws 0.70 cm t 49 DAI (Figure 2). The results otined here gree with those reported y Trionfetti-Nisini et l. (12), who oserved in melon plnts cv. Proteo grfted onto Benincs hispid, Cucumis metuliferus nd Cucumis moscht the occurrence of D. ryonie symptoms, with lesions keeping restricted to rootstocks, not ffecting the grfting. The lesion non-expnsion is due to the rootstock resistnce to the fungus ttck, proly through the synthesis of new crohydrtes, especilly cllose nd cellulose, which re dded to the interior of the cell wll. This occurs when the pthogen strts mximum minimum men /5 23/5 30/5 6/6 13/6 20/6 27/6 4/7 11/7 18/7 25/7 1/8 8/8 15/8 22/8 29/8 5/9 12/9 Air temperture ºC Dte Figure 1. Mximum, minimum nd men temperture in the protected environment from 18/05/2009 to 18/09/2009, São Mnuel-SP FEPP - UNESP/ FCA, Brzil, Summ Phytopthol., Botuctu, v. 38, n. 2, p , 2012

3 Lesion men dimeter (cm) 4,00 3,50 3,00 2,50 2,00 1,50 1,00 0,50 0,00 Dinero/Bônus II Strong T./Bônus II Dys fter inocultion Figure 2. Lesion men dimeter (cm) in the rootstock region of Bônus II plnts grfted onto Strong Tos nd Dinero rootstocks. Mens followed y the sme letter do not differ ccording to Tukey s test t 5% proility. São Mnuel-SP FEPP - UNESP/FCA, Brzil, penetrting the cell wll, using hyphe or infectious hustori (6). This crohydrte deposition continues fter the pthogen penetrtion until it ecomes configured s dome or elongted, receiving the nme of ppill (1). The difference etween the numer of grfted nd ungrfted plnts surviving during the whole evlution period ws quite cler: t 14 dys fter inocultion, some Bônus II ungrfted plnts were lredy ded nd hd the stem cut t the region of the lesion cused y the fungus D. ryonie, nd over the experiment lmost ll plnts did not resist nd died (Figure 3). For some plnts grfted onto Dinero, the lesion developed up to the grft, leding to the deth of some of these plnts; the ltter, however, did not differ sttisticlly from the numer of plnts grfted onto Strong Tos rootstock, which ws highly resistnt nd did not led to plnt deth (Figure 3). These results gree with those of Crino et l. (3), who noted tht Incs hyrid melon plnts grfted onto the commercil rootstocks RS 841, 360 P, ES 99-13, Elsi were highly resistnt oth to Fusrium oxysporum f. sp. melonis strins 1 nd 2 (100% survivl) nd to D. ryonie, with lmost sent lesions nd leves with low disese rte, clerly differing from those grfted onto Belimo, Energi, Griffin, ES liscio nd the control Incs in the ungrfted form. Potssium hs een one of the most studied nutrients considering plnt resistnce to diseses nd pests, especilly over the lst two Tle 1. Summry of the nlysis of vrince (men squres nd coefficient of vrition) for lesion men dimeter ccording to plnt type (TP= grfted plnts) nd potssium level (K). São Mnuel-SP FEPP - UNESP/FCA, Brzil, Vrition Cuse DF MS 7 DAI MS 14 DAI MS 21 DAI MS 28 DAÍ MS 35 DAI MS 42 DAI MS 49 DAI MS 56 DAI TP * 3.18* 3.00* 3.02* 2.73* 2.80* 2.57* 3.09* K ns 0.02 ns 0.02 ns 0.01 ns 0.02 ns 0.01 ns 0.01 ns 0.01 ns TP x K ns 0.03 ns 0.02 ns 0.01 ns 0.02 ns 0.01 ns 0.03 ns 0.04 ns Blocks * 0.02 ns 0.01 ns 0.01 ns 0.03 ns 0.02 ns 0.01 ns 0.01 ns Residue Totl 49 CV (%) * Significnt t 5% proility. ns non-significnt t 5% proility. Originl dt trnsformed into (log(x+1)). Tle 2. Summry of the nlysis of vrince (men squres nd coefficient of vrition) for men numer of plnts per plot ccording to plnt type (TP= grfted nd ungrfted plnts) nd potssium levels (K). São Mnuel-SP FEPP - UNESP/FCA, Brzil, Vrition Cuse DF MS 14 DAI MS 21 DAI MS 28 DAI MS 35 DAI MS 42 DAI MS 49 DAI TP * 10.84* 14.97* 18.76* 19.77* 19.77* K ns 0.20 ns 0.17 ns 0.05 ns 0.07 ns 0.07 ns TP x K ns 0.02 ns 0.26 ns 0.08 ns 0.11 ns 0.11 ns Blocks ns 0.27 ns 0.13 ns 0.25 ns 0.17 ns 0.17 ns Residue Totl 74 CV (%) * Significnt t 5% proility. ns non-significnt t 5% proility. MS: Men squres. DAI: Dys fter inocultion Summ Phytopthol., Botuctu, v. 38, n. 2, p ,

4 Figure 3. Survivl of grfted nd ungrfted melon plnts (%) t every seven dys fter inocultion. Mens followed y the sme letter did not differ ccording to Tukey s test t 5% proility. São Mnuel-SP FEPP - UNESP/FCA, Brzil, decdes when results were otined for some diseses or pests ffecting certin plnts. However, in the present experiments, this nutrient did not influence the lesion men dimeter or the plnt survivl (Tles 1 nd 2), lthough in the literture there re 2449 reports on the reltionship etween potssium nd plnt helth considering diseses nd pests, with emphsis on fungl diseses (8,6). The results otined in this study lso gree with those of Sntos et l. (10) who evluted different nitrogen nd potssium levels in cover fertiliztion on stem cnker cused y D. ryonie in wtermelon; those uthors lso noted tht fertiliztion did not influence the disese severity, similrly to 15 out of other 200 studies reviewed y Prhu et l. (9). Although potssium did not influence the lesion dimeter nd the severity cused y the fungus D. ryonie, in the literture there is evidence of correltions etween the plnt nutritionl sttus of K nd the incidence of diseses, ut ccording to Amtmnn et l. (2) there is lso cler need of studies relted to the effects of K on physiologicl, metolic nd hormonl processes, which tend to e essentil for the plnt susceptiility nd sensitivity to pthogenic gents nd insects, to etter estlish these correltions. D. ryonie is not soil fungus ut cn survive for long time in the soil of plces with previous incidence. Thus, grfting hs een studied s n lterntive to control this fungus oth in Brzil nd worldwide since chemicl control hs een inefficient; it my ecome tool for producers of melon nd the remining Cucuritcee in protected environment, s lredy used s n lterntive to control Fusrium oxysporum f. sp. melonis strins 1 nd 2 nd some other physiologicl disturnces tht ffect this fmily. The rootstock Strong Tos ws highly resistnt to the fungus nd cn e n lterntive control. ACKNOWLEDGMENTS The uthors thnk the compnies Skt Sudmeric Seed (provider of isoltes), Syngent nd Brzil Seeds Tkki (provider of rootstocks) nd CAPES (finncil support). REFERENCES 01. Aist, J. R. Ppille nd relted wound plugs of plnt cells. Annul Review of Phytopthology, St. Pul, v. 14, p , Amtmnn, A.; Trouffl, S.; Armengud, P. The effect of potssium nutrition on pest nd disese resistnce in plnts. Physiologi Plntrum, Copenhgen, v. 133, n. 4, p , Crino, P.; Binco, C.; Rouphel, Y.; Coll, G.; Sccrdo, F.; Prtore, A. Evlution of rootstock resistnce to Fusrium wilt nd gummy stem light nd effect on yield nd qulity of grfted Inodorus melon. HortScience, Alexndri, v. 42, n. 3, p , Ito, L.A.; Brz, L.T.; Cstoldi, R.; Chrlo, H.C.O.; Cmrgo, M. Seleção de ports enxertos resistentes o Cncro d hste e seus efeitos n produtividde de melão Bônus 2. Revist Brsileir de Fruticultur. Joticl, v. 31, n. 1, p , mr Kno, C. Extrções de nutrientes pelo meloeiro rendilhdo cultivdo em miente protegido com dição de potássio e CO n águ de irrigção f. Dissertção (Mestrdo em Agronomi) - Escol Superior de Agricultur Luiz de Quei- 2 roz, Universidde de São Pulo, Pircic, Mlvolt, E. Mnul de nutrição minerl de plnts. São Pulo: Agronômic Ceres, p. 07. Mtiello, R. R.; Brieri, R. L.; Crvlho, F. I. F. Resistênci ds plnts moléstis fúngics. Ciênci Rurl, Snt Mri, v.27, n.1, p , Perrenoud, S.: Potssium nd plnt helth. 2º ed. rev. Bern: Interntionl Potsh Institute, p. 09. Prhu, A.S.; Fgeri, N.K.; Huer, D.M. Potssium nutrition nd plnt diseses. In: (Eds.) Dtnoff, L.E; Elmer, W.H.; Huer, D.M. Minerl nutrition nd plnt disese. Sint Pul: The Americn Phytopthologicl Society Press, p Sntos, G. R.; Cfé-Filho, A.C.; Soy, L.M.F. Controle químico do crestmento gomoso do cule n cultur d melnci. Fitoptologi Brsileir, Brsíli, v. 30, p , Sitterly, W.R. Effect of crop rottion on cucumer gumy stem light. Plnt Disese, Sint Pul, v. 53, p , Trionfetti-Nisini, P.; Buzi, A.; Grnti, E.; Chilosi, G.; Crino, P.; Mgro, P. Screening for resistnce to Didymell ryonie in rootstocks of melon. OEPP Bulletin, Pris, v. 30, n. 2, p , Summ Phytopthol., Botuctu, v. 38, n. 2, p , 2012

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