Romnin Biotechnologicl Letters Vol. 21, No. 3, 2016 Copyright 2016 University of Buchrest Printed in Romni. All rights reserved ORIGINAL PAPER Divergent Selection for Resistnt Genotypes to Fusrium Wilt from n Old Melon Cultivr nd their Performnce in Grfting Received for publiction, July 17 th, 2014 Accepted, August 1 st, 2015 METAXIA KOUTSIKA-SOTIRIOU *, ELENI ANTHIMIDOU *, GEORGIOS MENEXES **, EKATERINI TRAKA-MAVRONA *** * Aristotle University of Thessloniki, School of Agriculture, Lbortory of Genetics nd Plnt Breeding, 541 24 Thessloniki, Greece ** Aristotle University of Thessloniki, School of Agriculture, Lbortory of Agronomy, 541 24 Thessloniki, Greece *** Hellenic Agriculturl Orgniztion DEMETER, Directorte Generl of Agriculturl Reserch, Agriculturl Reserch Center of Northern Greece, 570 01 Thermi-Thessloniki, Greece * Corresponding uthor: Tel.: +30-2310-998635, E-mil: koutsik@gro.uth.gr Abstrct This study concerns three successive reserch projects iming t common finl outcome: ) the divergent selection in the winter melon old cultivr Thrkiotiko (Cucumis melo L., group Inodorus, csb type) for resistnt genotypes to Fusrium wilt, which resulted in the development of two resistnt popultions to Fusrium oxysporum f.sp. melonis: Thrkiotiko-1 nd Thrkiotiko-2, b) the breeding mnipultions of the old cultivr to chieve uniformity nd stbility in yield nd qulity in new cultivr, which ws registered in the ntionl nd Europen ctlogues of vegetble species s Thrkiotiko, nd c) the performnce of the new melon cultivr s scion tested on four rootstocks: Thrkiotiko-1 nd Thrkiotiko-2, Mnt (C. melo, group cntlupensis) nd TZ-148 (interspecific Cucurbit spp. hybrid). Using the improved cultivr Thrkiotiko nd the gli type hybrid Msd s scions, on the rootstock Thrkiotiko-1 significntly incresed yield by 36 compred to the ungrfted control, wheres the performnce of the sme rootstock used for Msd ws similr to tht of the other melon rootstocks nd the control. In ddition, Thrkiotiko-1 improved fruit qulity in both grfted cultivrs. Thrkiotiko-2 performed similrly to the commercil rootstocks, without differing significntly from the control. Keywords: Cucumis melo L., Fusrium oxysporum f.sp. melonis, pedigree selection 1. Introduction Divergent selection cts on the genetic vrition tht exists in lndrce or in n old popultion nd focuses on genotypes tht hve high devition from the men performnce of the popultion, i.e. low frequency of ppernce. Divergent selection for resistnce ws pplied to unbred genetic mterils (L.X. HAN & l. [1]), nd to locl cultivrs (A. CLAESSENS & l. [2]). Multi-test for resistnce of selected genotypes nd progeny-test re lwys necessry for resistnce verifiction. Conventionl breeding methods result in the nrrowing of the genetic bse, in vulnerbility to biotic nd biotic stress, in limiting future gins from selection (J.M. TAILLER & R. BERNARDO [3]), conducive to the stgntion of yields (A.C. NEWTON & l. [4]), nd in mintining soil-borne pthogens (S.R. KING & l. [5]). The involvement in Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016 11599
METAXIA KOUTSIKA-SOTIRIOU, ELENI ANTHIMIDOU, GEORGIOS MENEXES, EKATERINI TRAKA-MAVRONA breeding of lndrces nd old cultivrs offers solution by brodening the genetic diversity of the source mteril (M. KOUTSIKA-SOTIRIOU & l. [6]). Despite erlier predictions bout their imminent disppernce (A.C. ZEVEN [7]), lndrces nd locl cultivrs still support frming owing to their stbility, qulity of the end product nd compenstion (M. KOUTSIKA-SOTIRIOU & l. [6]). On the other hnd, the use of lndrces nd the exploittion of their genetic qulities, represent relible solution for sustinble griculture in the forthcoming yers in the context of climte chnge (A.C. NEWTON & l. [4). The genetic diversifiction of lndrces long with their prticiption to modern frming techniques, such s grfting, cn be considered s n effective method for controlling biotic nd biotic stress, nd improving yield nd qulity in mny cultivted plnts like melon. Grfting (S.R. KING & l. [5]), is routine technique used in continuous cropping of fruit-bering vegetbles, such s wtermelon, melon, cucumber, tomto, nd eggplnt, in order to control successfully soil-borne diseses nd improve the response of the crop to vriety of biotic conditions, nd finlly improve fruit qulity nd yield. During the lst decdes, mny grfting methods hve evolved, lwys following the four principles of the grfting procedure: () choice of suitble rootstock nd scion species, (b) development of grft union by physicl mnipultion, (c) enhncement of meristemic tissue of the grfted plnt, nd (d) cclimtiztion of the grfted plnt (J.M. LEE & l. [8]). Fusrium wilt of melons my severely ffect cultivr during the developmentl stges of the plnt, mostly t the ripening stge of the fruits (R.D. MARTYN & T.R. GORDON [9]). In melon, two forme speciles of F. oxysporum hve been described: () F. oxysporum f.sp. melonis (FOM), nd (b) F. oxysporum f.sp rdicis-cucumerinum (FORC) (D.J. VAKALOUNAKIS & l. [10]). Concerning the pthogen FOM, four rces (0, 1, 2 nd 1.2) re known (R.D. MARTYN & T.R. GORDON [9], G. RISSER & l. [11], R. COHEN & l. [12]). Resistnce to Fusrium wilt is controlled by three mjor genes, the: Fom-1, which offers resistnce to the rces 0 nd 2, Fom-2, which offers resistnce to the rces 0 nd 1, nd Fom-3, which offers resistnce to the rces 0 nd 2 (G. RISSER [13], F.W. ZINK & W.D. GUBLER [14]). Mny resistnt vrieties hve evolved due to the introduction of resistnt genes derived from different ccessions of melon ll over the world (M. PITRAT [15]). The objective of the present study ws to evlute the outcome of grfting system in melon when the genetic resource is n old cultivr nd the prospective result is the performnce of the grfted plnts. For this reson, series of successive experiments were conducted. 2. Mterils nd methods 2.1. Divergent selection procedure The source smples of the winter melon old cultivr Thrkiotiko were obtined by selecting in situ resistnt plnts in privte frms infected by Fusrium spp. in the villges Peplos, Petlo nd Tichero, prefecture Evros, Thrki (40 o 95 N. Lt. 26 o 28 E. Long.), where the old cultivr is widely cultivted. Eleven smples were selected on the bsis of seed nd fruit chrcteristics. In ddition smple of the commercilly mrketble seed of Thrkiotiko (i.e. the sensitive cultivr to Fusrium spp.), sold loclly, ws used s control. Twenty seeds from ech smple nd the control were sown in seed beds composed of pet moss nd perlite (10:1 v/v). Seedlings were trnsplnted in pots t the first true lef stge. Prior to trnsplnting, the roots of the seedlings were dipped for 15 minutes in conidil suspension of 10 6 conidi/ml of the pthogen F. oxysporum f.sp. melonis (FOM), rces 0, 1 11600 Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016
Divergent Selection for Resistnt Genotypes to Fusrium Wilt from n Old Melon Cultivr nd their Performnce in Grfting nd 2 ( kind offer by Dr. Demetrios Vklounkis, Hellenic Agriculturl Orgniztion DEMETER, Directorte Generl of Agriculturl Reserch, Plnt Protection Institute, Herklion, Crete, personl communiction). To produce bundnt inoculum in the form of conidi the Armstrong Fusrium medium ws chosen (L.L. SINGLETON & l. [16]). Subsequently, the inoculted plnts were irrigted with spore suspension of the sme density three times dily for three consecutive dys fter trnsplnting. The inoculted plnts were kept in growth chmber t 23 0 C, RH 70 nd 16/8 hours photoperiod. Ten dys lter, the response of ech plnt ws exmined nd recorded for period of four weeks in disese scle 0-3 (0: no symptoms, 3: ded plnts). Sixteen plnts survived out of 240, belonging to eight popultions, which were rndomly seprted into two groups of eight plnts ech (Tble 1). The resistnt genotypes of ech group were propgted in two isolted fields nturlly infested, t loction 1 (University Frm of Aristotle University of Thessloniki, 40 o 32 N Lt., 22 o 59 E Long.), nd t loction 2 (Gltist, prefecture Chlkidiki, 40 o 28 N. Lt., 23 o 16 E. Long.). At the end of the hrvest period, the infection of the plnts in ech group ws verified by histologicl exmintion. Three plnts from ech loction were not ffected by FOM. The seeds from the non-ffected plnts were extrcted, stored nd comprised the core collection of the two resistnt popultions, nmed Thrkiotiko-1 from loction 1 nd Thrkiotiko-2 from loction 2, for the study of performnce in rootstock-scion system. 2.2. Breeding mnipultions of the old cultivr Firstly, the existing phenotypic vribility, in 10 gronomic nd qulittive chrcteristics, of the old cultivr Thrkiotiko ws studied, in 1999, in non-replicted NR- 0 honeycomb design (A.C. FASOULAS [17]), of 320 plnts. Combined pedigree selection, bsed on single-plnt performnce for high yield, qulity of the end product nd stbility of performnce ws pplied, nd resulted in 6.56 selection pressure, i.e. 21 plnts. Secondly, 714 plnts were rrnged in n R-21 honeycomb design for 1 st cycle evlution, ech one of the 21 selected plnts represented by 34 offsprings. Combined pedigree selection ws pplied with the prementioned criteri. The 2 nd nd 3 rd cycle progenies were subsequently evluted following the sme selection procedure (M. KOUTSIKA-SOTIRIOU & l. [18]). The new melon cultivr ws registered in the ntionl nd Europen ctlogues of vegetble species s Thrkiotiko. 2.3. Grfting experiment The products of the previous experiments were combined in rootstock-scion system. The cultivrs used s rootstocks were: (i) Thrkiotiko-1 nd (ii) Thrkiotiko-2 (derived from the old cultivr Thrkiotiko through divergent selection for resistnt genotypes to FOM, s described bove), (iii) Mnt (Cluse Vegetble Seeds), commercil F1 hybrid of C. melo L., Cntloupensis group, chrentis type, nd (iv) TZ-148 (Geoponiko Spiti, Greece), commercil interspecific hybrid of Cucurbit spp. Ungrfted Thrkiotiko nd Msd plnts were used s controls. The product of the improved nd registered melon cultivr Thrkiotiko nd the F1 commercil hybrid Msd (Cluse Vegetble Seeds) were evluted s scions. Thrkiotiko (C. melo L., Inodorus group), csb type winter melon, hs boxy nerly round fruit, strongly tpered t the stem end, with firm flesh, white nd sweet, nd cucumber like rom. Fruit do not bscise nd hve long storge life. Trditionlly, the cultivr is grown in the open for locl consumption or long-distnce trnsport to mrkets in utumn-winter months. Msd (C. melo L., Reticultus group), gli type medium erly melon, is cross between Gli nd the spnish Souehl (C. melo Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016 11601
METAXIA KOUTSIKA-SOTIRIOU, ELENI ANTHIMIDOU, GEORGIOS MENEXES, EKATERINI TRAKA-MAVRONA L., Inodorus group). Fruit re round, very strong netted, with white flesh, sweet nd romtic. The experiment ws conducted in the Aristotle University of Thessloniki frm during 2009. Seeds of scions nd melon rootstocks were sown on 10 April, while the TZ-148 rootstock ws sown on 17 April, to ensure uniformity in hypocotyl dimeter for grfting. Seedlings were grfted by the splice grfting pproch on 7 My nd the grfted plnts were trnsplnted on 1 June in the open field, t distnces of 150 cm within rows nd 200 cm between rows. Norml culturl prctices for fertiliztion nd irrigtion were pplied. The experiment lsted till 8 September. 2.4. Mesurements of breeding nd grfting experiments - Sttisticl nlyses The following mesurements were recorded: (i) the components of yield potentil, i.e. fruit number per plnt, fruit yield per plnt (kg.plnt -1 ) nd fruit size (kg.fruit -1 ); (ii) descriptive chrcteristics, i.e. shpe of the fruit nd the plcent, clculted s the quotient of equtoril nd polr dimeter, thickness of mesocrp (cm) nd for the grfting experiment, thickness of pericrp (cm); nd (iii) qulittive chrcteristics of the flesh, i.e. totl soluble solids (TSS), totl solids (TS) nd ph. Additionlly, flesh tste nd texture were recorded in the breeding experiments, ccording to 1-5 scle (1 = very bd, 2 = bd, 3 = medium, 4 = good, 5 = very good for tste nd 1 = very spongy, 2 = spongy, 3 = medium, 4 = fine, 5 = very fine for texture). Reported dt on descriptive nd qulittive chrcteristics were tken from two fruits per plnt. Replicted honeycomb designs were nlyzed by pplying computer progrm, which ws build for plnt selection nd nlysis of honeycomb designs (D.P. BATZIOS & D.G. ROUPAKIAS [19]). Anlysis of vrince (ANOVA) ws performed on the dt for the grfting experiment ccording to 2 5 Generlized Rndomized Complete-Block Design in split plot rrngement with 3 blocks. The two scion-cultivrs were considered s the min plots, nd the five rootstocks s the sub-plots. In ech block there were 10 plnts (replictions) per tretment. This methodologicl pproch for sttisticl nlysis fits better to the setup nd the purpose of the experiment. After significnt interction effect between scion nd rootstock, two simple min effects nlyses were performed, οne to compre rootstock mens within ech scion nd second to compre the two scions for the sme rootstock. The mens were compred by using Fisher s lest significnt difference (LSD) t p 0.05. Prior to nlyses, dt for yield components (fruit number, fruit yield, fruit size) were log10 trnsformed in order to chieve homogeneity of vrince nd normlity. Men vlues of trnsformed dt were bck-trnsformed for tbulted presenttion in the mnuscript. All the sttisticl nlyses were performed using SPSS v.15.0. 3. Results 3.1. Divergent selection Divergent selection in the old cultivr Thrkiotiko conduced to core collection of resistnt to the pthogen F. oxysporum f.sp. melonis genotypes (Tble 1). The helthy plnts were estblished t two loctions nd two resistnt popultions were obtined, nmed fter the loction where they were multiplied: Thrkiotiko-1 nd Thrkiotiko-2. 11602 Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016
Divergent Selection for Resistnt Genotypes to Fusrium Wilt from n Old Melon Cultivr nd their Performnce in Grfting Tble 1. Mortlity rte () through seven mesurements of plnts of smples (S), selected for resistnce to F. oxysporum f.sp. melonis, nd number of trnsplnted plnts t two loctions. Mesurements Disese scle (0-3) S2 S4 S6 S7 S8 S10 S11 Control 1 st 3 - - - - - - - - 2 nd 3 20-16.7 - - - - - 3 rd 3 25 60 20 50 80 50 20 75 4 th 3 66.7 40 20 50 80 50 40 75 5 th 3 66.7 60 20 50 80 50 40 75 6 th 3 66.7 60 20 50 80 50 40 75 7 th 3 66.7 60 20 50 80 50 40 75 Trnsplnted plnts 0: no symptoms, 3: ded plnts. 1 2 4 2 1 2 3 1 3.2. Breeding mnipultions on the old cultivr Tble 2. Components of yield cpcity through cycles of selection in the old cultivr Thrkiotiko nd the coefficient of vrition for ech entry. Entry Fruit yield Fruit size No. of fruits.plnt -1 Kg.plnt -1 Kg.fruit -1 Avg CV Avg CV vg CV Source mteril 3.17 52 5.86 63 1.82 35 1 st cycle progenies 2.61 44 2.47 43 1.99 25 2 nd cycle progenies 2.25 44 4.26 48 1.92 26 3 rd cycle progenies 2.64 43 3.74 43 1.70 25 Thrkiotiko hs been registered s winter melon cultivr of csb type in the ntionl nd Europen ctlogue of vegetble species (Officil Gzette of Government 584/B/13-05-2003). It is prerequisite for ech cultivr to be distinct, uniform nd stble in plnt descriptive chrcteristics. Thrkiotiko showed yield stbility (Tble 2), s it ws verified by decrese in the coefficient of vrition (CV vlue) in yield components, n indiction of efficient selection (A.C. FASOULAS [17]). In ddition, it showed stbility of descriptive chrcteristics (Tble 3), nd it retined the fruit qulity chrcteristics of the originl old cultivr (Tble 4). The CV vlue is the most widely used prmeter to quntify vribility mong individul plnts of crop stnd (G.D. EDMEADES & T.B. DAYNARD [20]) nd wy to estimte yield improvement (M. TOLLENAAR & J. WU [21]). Tble 3. Fruit descriptive chrcteristics through cycles of selection in the old cultivr Thrkiotiko nd the coefficient of vrition for ech entry. Entry Fruit shpe Plcent shpe Mesocrp thickness (cm) vg CV Avg CV Avg CV Source mteril 0.90 10 0.80 15 2.78 17 1 st cycle progenies 0.84 11 0.77 15 3.11 16 2 nd cycle progenies 0.89 7 0.79 16 2.73 18 3 rd cycle progenies 0.94 7 0.79 13 2.90 16 clculted s quotient of equtoril dimeter nd polr dimeter. Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016 11603
METAXIA KOUTSIKA-SOTIRIOU, ELENI ANTHIMIDOU, GEORGIOS MENEXES, EKATERINI TRAKA-MAVRONA Tble 4. Fruit qulittive chrcteristics through cycles of selection in the old cultivr Thrkiotiko nd the coefficient of vrition for ech entry. Entry TSS() Tste b Texture c ph vg CV vg CV vg CV vg CV Source mteril 8.18 23 3.79 28 4.00 23 5.81 3 1 st cycle progenies 6.78 25 2.92 41 3.29 26 5.84 3 2 nd cycle progenies 10.21 23 4.20 21 4.26 18 5.85 3 3 rd cycle progenies 10.15 21 4.17 23 4.79 9 6.09 3 Totl soluble solids of edible flesh. b Flesh tste on scle 1-5 (1 = very bd, 2 = bd, 3 = medium, 4 = good, 5 = very good). c Flesh texture on scle 1-5 (1 = very spongy, 2 = spongy, 3 = medium, 4 = fine, 5 = very fine). 3.3. Grfting performnce 3.3.1. Yield performnce. Totl number of fruits per plnt of the scion-cultivr Thrkiotiko ws not significntly ffected by grfting, wheres grfted plnts of ll tretments of the scion-cultivr Msd hd significntly lower number of fruits per plnt thn the control (Tble 5), which, consequently, led to n increse in fruit size compred to the control, irrespective of rootstock. Fruit yield ws ffected, in both cultivrs by grfting, with the combintion of Thrkiotiko on Thrkiotiko-1 exhibiting significnt increse in yield by 36 over the control but without significnt differences from the other melon rootstocks. Thrkiotiko-2 ws not differentited from the commercil rootstocks nd the control. The combintion Msd / TZ-148 gve the higher yield, but without significnt differences from the combintions of Msd with Mnt or Thrkiotiko-2 or the control. From the comprison of both scion-cultivrs within ech rootstock the results showed tht lthough the scion-rootstock interction did not ffect the number of fruits plnt -1, it ffected significntly fruit yield plnt -1 in the cse of Mnt (p = 0.016) nd TZ-148 (p=0.000) rootstock. Fruit size ws dditionlly ffected by Thrkiotiko-2 rootstock. Controls of both scion cultivrs were significntly differentited in yield components. 3.3.2. Descriptive chrcteristics. Fruit shpe ws ffected by the rootstock only in the scion-cultivr Thrkiotiko, but not differing significntly from the control (Tble 6). Similrly, the shpe of the plcent cvity ws not ffected in Msd, wheres it ws ffected significntly in Thrkiotiko minly by the melon rootstocks. The mesocrp thickness in ll combintions of Msd incresed significntly by grfting compred to the control, while the Thrkiotiko ungrfted control hd the thickest edible flesh. The pericrp thickness ws ffected by grfting only in Thrkiotiko, while the control, with the thickest mesocrp, hd the thinnest pericrp. The comprison of scion-cultivrs within ech rootstock showed regrding the shpe of the fruit nd the thickness of the pericrp, significnt or highly significnt differentitions (p = 0.000 p = 0.014). The shpe of the plcent cvity nd the thickness of the edible flesh, lthough similr in the ungrfted plnts of both cultivrs, they were ffected by the rootstock (p = 0.000 p = 0.05). 11604 Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016
Divergent Selection for Resistnt Genotypes to Fusrium Wilt from n Old Melon Cultivr nd their Performnce in Grfting Tble 5. Grfting performnce in yield components of grfted nd ungrfted plnts. Tretments (scion rootstock) Fruit No.plnt -1 Fruit yield Kg.plnt -1 Fruit size Kg.fruit -1 Thrkiotiko Thrk.-1 2.85 4.34 1.55 Thrkiotiko Thrk.-2 2.38 3.25b 1.40 Thrkiotiko Mnt 2.75 3.56b 1.49 Thrkiotiko TZ-148 2.17 3.09b 1.66 Thrkiotiko (ungrfted) 2.20 3.18b 1.55 Msd Thrk.-1 2.45B 3.97B 1.65B Msd Thrk.-2 2.54B 4.40AB 1.78AB Msd Mnt 2.84B 5.17AB 1.91A Msd TZ-148 2.65B 5.31A 2.01A Msd (ungrfted) 3.83A 4.54AB 1.25C Men vlues in the sme column within ech scion-cultivrs followed by common letter (lowercse for Thrkiotiko nd uppercse for Msd ) re not sttisticlly significnt different t p=0.05 ccording to LSD criterion. Tble 6. Grfting performnce in descriptive chrcteristics of grfted nd ungrfted plnts. Tretments (scion rootstock) Fruit shpe Plcent shpe Mesocrp thickness (cm) Pericrp thickness (cm) Thrkiotiko Thrk.-1 1.04bc b 0.81 3.09b 0.68 Thrkiotiko Thrk.-2 1.08b 0.76b 3.25b 0.62 Thrkiotiko Mnt 1.03c 0.82 3.09b 0.68 Thrkiotiko TZ-148 1.11 0.74b 3.24 0.67 Thrkiotiko (ungrfted) 1.07bc 0.72b 3.51 0.55c Msd Thrk.-1 0.95A 0.71A 4.01B 0.50A Msd Thrk.-2 0.97A 0.67A 4.27AB 0.50A Msd Mnt 0.96A 0.68A 4.48A 0.52A Msd TZ-148 0.95A 0.67A 4.57A 0.50A Msd (ungrfted) 0.93A 0.71A 3.67C 0.51A clculted s quotient of equtoril dimeter nd polr dimeter. b Men vlues in the sme column within ech scion-cultivrs followed by common letter (lowercse for Thrkiotiko nd uppercse for Msd ) re not sttisticlly significnt different t p=0.05 ccording to LSD criterion. 3.3.3. Qulittive chrcteristics. Qulittive chrcteristics (Tble 7) were significntly ffected by grfting, with Thrkiotiko-1 to improve significntly the totl soluble solids of the fruit in Msd (11.39 compred to 10.16 of the control), nd mintin the high qulity of Thrkiotiko (9.14 compred to 9.20 of the control). Thrkiotiko-2 s rootstock showed behvior similr to commercil rootstocks, i.e. cused decrese in TSS in Thrkiotiko but did not ffect TSS in Msd, compred to the control. The totl solids were similrly ffected by the rootstock in both cultivrs. The ph of the fruit flesh ws ffected significntly minly by Thrkiotiko-2 rootstock. The comprison of scion-cultivrs within ech rootstock cultivr showed highly significnt differences in ll qulittive chrcteristics (p = 0.001 p = 0.000). Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016 11605
METAXIA KOUTSIKA-SOTIRIOU, ELENI ANTHIMIDOU, GEORGIOS MENEXES, EKATERINI TRAKA-MAVRONA Tble 7. Grfting performnce in qulittive chrcteristics of grfted nd ungrfted plnts. Tretments TSS ph TS b (scion rootstock) Thrkiotiko Thrk.-1 9.14 c 5.85 8.76 Thrkiotiko Thrk.-2 7.38b 5.68b 6.48bc Thrkiotiko Mnt 7.24b 5.80b 6.29c Thrkiotiko TZ-148 7.94b 5.78b 7.29b Thrkiotiko (ungrfted) 9.20 5.84 8.61 Msd Thrk.-1 11.39A 6.10ABC 10.96A Msd Thrk.-2 10.84B 6.15A 10.14AB Msd Mnt 10.61AB 6.12AB 9.85AB Msd TZ-148 10.11B 6.00BC 9.34B Msd (ungrfted) 10.16B 5.98C 9.58B Totl soluble solids of edible flesh. b Totl solids of edible flesh. c Men vlues in the sme column within ech scion-cultivrs followed by common letter (lowercse for Thrkiotiko nd uppercse for Msd ) re not sttisticlly significnt different t p=0.05 ccording to LSD criterion. 4. Discussion Grfting is one of methods used for the depression of soil borne pthogens. Intrspecific grfting occurs when rootstock nd scion re of the sme species, while interspecific grfting occurs when the combintion of rootstock nd scion re of different species or gener. Grfting melon onto Cucurbit species provides non-specific but sufficient protection ginst vst rnge of pthogens nd of some biotic fctors, but it cn lso ffect, negtively, yield nd fruit qulity (J.M. LEE [22], M. ODA [23]). On the contrry, intrspecific grfting hs less negtive effects on qulity nd fruit yield, s well s scion-rootstock comptibility, but provides specific resistnce ginst specific rces of the pthogen tht my be overcome by indigenous or novel rces of the comptible pthogen (F.J. LOUWS & l. [24]). From the results it is cler tht there is definite scion-rootstock interction regrding gronomic nd qulittive chrcteristics, which verifies the concept tht the grfting technique ws effective for the tested cultivrs. It ws demonstrted tht grfting per se ffects directly plnt yield (G. NIELSEN & F. KAPPEL [25], R.M. RIVERO & l. [26], G. COLLA & l. [27]). Its influence cn be exerted by the interction of vrious processes, such s increse in wter nd nutrient uptke resulting from the rootstock vigorous root system (J.M. LEE [22], J.M. RUITZ & l. [28]), enhnced production of endogenous hormones (S. ZIJLSTRA & l. [29]), nd enhncement of scion vigor (S. LEONI & l. [30]). The joint ction of some or ll of these processes could explin the higher yield of melon plnts grfted on melon or Cucurbit spp. rootstocks, by 36 nd 16.9, respectively, compred to the control (Tble 5). However, the TZ-148 did not increse fruit yield of Thrkiotiko, while the melon rootstock Thrkiotiko-1 did not fvor fruit yield of Msd, differing significntly from TZ-148. Regrding the response of the rest melon rootstocks, i.e Thrkiotiko-2 nd Mnt, they were not significntly differentited from Thrkiotiko-1 nd TZ-148, respectively. For other yield components there were lso conflicting results in both scion cultivrs. So, fruit number per plnt in Thrkiotiko ws not ffected by ny rootstock, while in Msd fruit number decresed nd fruit size incresed significntly compred to the control, indicting cler effect of the root system of ll rootstocks tested. Concluding, the highest yields recorded in the current experiment were not observed on ll 11606 Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016
Divergent Selection for Resistnt Genotypes to Fusrium Wilt from n Old Melon Cultivr nd their Performnce in Grfting scion/rootstock combintions, suggesting tht n ccurte gronomic evlution of the rootstock-scion combintion is still necessry before using them on commercil scle. Regrding descriptive chrcteristics (Tble 6), fruit shpe ws not significntly ffected in both cultivrs with regrd to the control, wheres there were significnt effects in plcent shpe of Thrkiotiko. According to E. TRAKA-MAVRONA & l. [31], fruit shpe of four melon cultivrs of the Inodorus nd Cntlupensis group ws not ffected by grfting onto Cucurbit rootstocks. The thickness of mesocrp in grfted plnts of Msd ws significntly higher thn the control, indicting positive effect of grfting in the direction of incresing the edible flesh. However, such n effect ws not clerly identified in the cse of the winter cultivr Thrkiotiko. Regrding qulittive chrcteristics, grfting of both cultivrs onto Thrkiotiko-1 improved or mintined fruit qulity, expressed in totl soluble solids nd totl solids, compred to the control (Tble 7). P. CRINO & l. [32] found tht fruit dry mtter, titrtble cidity, totl soluble solids, fruit firmness, nd Hunter color of grfted melons of Inodorus group onto melon nd Cucurbit spp. rootstocks were similr to those of plnts grown on their own roots. In greement with R. COHEN & l [12], the response of Cucurbit spp. rootstock TZ-148 ws not diversified from tht of the rest melon rootstocks, i.e Thrkiotiko- 2 nd Mnt, in both scion cultivrs, indicting tht the decrese in qulity of melons grfted onto Cucurbit rootstocks (E. TRAKA-MAVRONA & l. [31]) resulted rther from prticulr scion/rootstock interction, nd prticulr combintion of growing conditions. Sustinbility is the bility of n groecosystem to mintin production through time, in the fce of long-term ecologicl constrins nd socioeconomic pressures (M.A. ALTIERI & I.C. MERRICK [33]). The vlue of locl cultivrs/lndrces is minly ttributed to the wide rnge of genetic resistnce ginst biotic nd biotic stress, rendering them desirble for doption in sustinble griculturl system. Currently, the need for incresed sustinbility of performnce in cultivrs is socio-politicl demnd. Efforts to compre the outcome of breeding progrms nd combine them to rootstock-scion system re not only chllenge but necessity. Tody, the pressure to move towrds sustinble griculture cretes the necessity to: (i) hve ccess to exploit nd incorporte broder germplsm nd (ii) develop cultivrs specificlly dpted to chnging frming systems (M. KOUTSIKA- SOTIRIOU & l. [6]). The genetic improvement protocols described in this work, bsed on the principle of sustinbility, mke use of phytogenetic resources, such s locl cultivrs nd lndrces, enriching the genetic bse of cultivted plnts, the melon in this cse, for the benefit of commercil vegetble production. In fct, the present study describes protocol following which resistnt genotypes within locl cultivrs of melon cn be isolted nd cn be used in the future s vluble source of genes for the development of resistnt rootstocks to the pthogen of Fusrium wilt. Besides, the interspecies grfting in plnts cuses heritble epigenetic modifictions, s shown by R. WU & l. [34]. The reserch for rootstocks derived from lndrces/old cultivrs relevnt to ech species will inhibit the phenomen of heritble ltertions of DNA methyltion. The whole procedure for developing rootstocks is bsed on the interntionl trety on plnt genetic resources for food nd qulity (http://www.plnttrety.org), which supports sustinble griculture nd food security. In ddition, the present work confers right nd title (N.W. SIMMONDS [35]) in locl cultivr, tht psses the prescribed tests for distinctness, uniformity nd stbility; the new cultivr Thrkiotiko is required to be not only cceptble but lso positively superior. In this wy, the rising benefits for frmers nd locl communities re two-fold: conserve on-frm the genetic resources nd utilize them in grfting system. Romnin Biotechnologicl Letters, Vol. 21, No. 3, 2016 11607
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