105 EFFECTS OF PRE-HARVEST METHYL JASMONATE TREATMENT ON POST-HARVEST FRUIT QUALITY OF JAPANESE PLUMS

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1 5 EFFETS OF PRE-HRVEST METHYL JSMONTE TRETMENT ON POST-HRVEST FRUIT QULITY OF JPNESE PLUMS Emine Kucuker 1*, urhn Ozturk 2* 1 Deprtment of Horticulture, Fculty of griculture, University of Gziosmnpş, 62, Tokt-Turkey, 2 Deprtment of Horticulture, Fculty of griculture, University of Ordu, 52, Ordu-Turkey. * orrespondence to: Emine Kucuker, e-mil: emine2346@gmil.com; urhn Ozturk, e-mil: urhnozturk55@gmil.com Emine Kucuker nd urhn Ozturk contriuted eqully to this work strct ckground: Plum fruits constitute good source of nturl ntioxidnt sustnces. Prticulrly, plums contin lrge mounts of phenolic compounds nd flvonoids hving nturl ntioxidnt ctivity which is effective in humn diet. The im of this study ws to evlute the effects of pre-hrvest MeJ tretment on the fruit qulity nd ioctive compounds of three different Jpnese plums under storge conditions. Mterils nd Methods: The effects of pre-hrvest methyl jsmonte tretment (MeJ) on weight loss, color chrcteristics (L*, * nd h ), firmness, solule solids content (SS), titrtle cidity (T), totl phenolics (TP) nd totl ntioxidnt ctivity (T) of lck euty, lck mer nd Fortune plum fruits during the cold storge (t ± nd 9±5% RH) were investigted in this study. Results: MeJ did not hve significnt effects on the weight loss (%) of lck mer nd Fortune fruits, wheres it ws effective in delying the weight loss of lck euty t the end of storge. The color chrcteristics of ll plum cultivrs were not significntly ffected y MeJ t the end of storge. In ll plum cultivrs, the SS incresed, while T significntly (P<5) decresed during storge. TP nd T of lck mer nd Fortune fruits significntly incresed during the cold storge. MeJ tretments incresed fruit firmness, TP nd T (ccording to FRP) of Fortune plums t the end of storge. onclusion: The scientific results out the effects of pre-hrvest MeJ tretments on the cold storge of Jpnese plums my contriute significnt helps to improve plum storge durtions nd qulity chrcteristics. Keywords: olor, firmness, totl phenolic, totl ntioxidnt, weight loss. Introduction Plums hve post-hrvest cold storge life of 2-8 weeks. Excessive softening of fruit flesh is the sic fctor shortening the storge nd shelf life of plums. Preservtion of fruit firmness lso provides the preservtion of tste, flvor nd fruit texture nd consequently increses plum consumption (risosto et l., 4). Softening in fruit flesh decreses the mrket life nd vlue of the fruit nd limits the fruits to closer mrkets. There re severl methods to prolong the storge life nd to preserve the fruit qulity. One of them is to pply plnt growth regultors efore nd fter hrvest. minoethoxyvinylglicine (VG), polymines (putrescine), 1-methylcyclopropene (1-MP) nd jsmontes (MeJ) re the most common growth regultors used for extending post-hrvest storge life of horticulturl crops (Joling et l., 3; Khn nd Singh, 7; Khn et l., 7; Khn nd Singh, ). Methyl jsmonte (MeJ), nturl plnt growth regultor, is phytohormone with uiquitous distriution mong plnts. Depending upon the plnt species, cultivr, stge of development nd climcteric stge, it modultes mny physiologicl events in higher plnts, such s defense responses, flowering, plnt growth nd development, senescence, fruit ripening, ethylene, nthocynin nd crotenoid synthesis (Fn et l., 1998; Rudell et l., 2; Rohwer nd Erwin, 8; rvlho et l., 11; Zpt et l., 14). Jsmonic cid nd its methyl ester, methyl jsmonte, function s sic signling compound in metolic rections of plnts (Rudell et l., 2; Rohwer nd Erwin, 8). Reserchers (Rudell et l., 2; Lrrondo et l., 3; Sniewski et l., 4; Jin et l., 9; Gong et l., 13) reported tht MeJ stimulted secondry metolites in grpevine, strwerry, pple, plum, pech nd mngo fruits. It ws lso reported tht MeJ incresed nthocynin ccumultion in pples nd strwerries, nd β-crotene ccumultion in tomto (Rudell et l., 5; Moreno et l., ). Khn nd Singh (7) reported tht post-hrvest exogenous MeJ pplictions to lck mer, mer Jewel nd ngelino plums positively ffected the ioctive compounds of plum fruits during ripening period. The im of this study ws to evlute the effects of pre-hrvest 22 mg L -1 MeJ tretment on weight loss, color chrcteristics, fruit firmness, SS, titrtle cidity, totl phenolics nd totl ntioxidnt ctivity of three different Jpnese plums under storge conditions t. Mterils nd Methods Plnt mteril Five-yers old uniform Jpnese plum trees (Prunus slicin Lindell cvs. lck euty, lck mer nd Fortune ) grfted on Myroln (Prunus ceresifer Ehrh.) rootstock from Horticulturl Reserch enter of Gziosmnpş University ( o ' 2.19"N ltitude, 36 o 28'.11"E longitude nd 623 m ove se level, Tokt, Turkey) were selected s the plnt mteril of the study. Experimentl design Experimentl design ws rndomized complete lock with three locks, ech of hving two trees. For ech plum cultivr, 6 trees were selected nd trees were grouped with 2 trees per lock sed on proximity in orchrd nd crop lod for ech plum cultivr. Methyl jsmonte dose ws pplied to one tree in ech lock nd the other tree of the lock ws considered s control. Experimentl trees were plnted in north-south direction with 4 x 4 m spcing. Trees were trined in modified-leder system.

2 MeJ (Sigm-ldrich, Tufkirchen, Germny) ws pplied 2 weeks efore the estimted hrvest dte t dose of 22 mg L -1. MeJ dose ws selected sed on previous studies crried out under field conditions. Only wter (with ph 6.48) ws used in control tretment trees. ll spry solutions contined Triton X- s surfctnt [(77%, v/v), lf esr, Krslruhe, Germny]. Tretments were pplied to runoff with low pressure hnd spryer s fruit nd folir sprys. Volume of solution is significnt to hve the mximum impct of MeJ over the fruit nd folir. Therefore, mount of solution to e pplied ws clculted y using the eqution developed y reserchers (nonymous, 11) nd ml solution ws spryed to ech tree. Shpe (conicl or sphericl), height nd row spcing were tken into considertion to clculte the mount of solution. MeJ ws spryed over trees erly in the morning of dy without wind nd precipittion. Fruit qulity ssessment The plum fruits were hrvested t the firm-ripe stge. lck euty plums were hrvested on July 15, lck mer on July 25 nd Fortune on ugust 4, 11. Plums with [with solule solids content of %, 9% nd 11% nd fruit firmness of 35 N, 5 N nd 55 N respectively for lck euty, lck mer nd Fortune ] uniform of shpe, color nd size nd free from visul symptoms of ny disese or lemishes were hrvested t the estimted hrvest dte. Thirty fruits were rndomly hrvested from ech tree in ech lock for ech tretment t the estimted hrvest dte of ech plum cultivr. Of these fruits, twenty were used to determine the fruit qulity chrcteristics (fruit firmness, SS nd T) nd ten fruits were used to determine totl phenolics (TP) nd totl ntioxidnt ctivity (T). ll fruit qulity chrcteristics nd ioctive compounds were replicted three times. In order to determine fruit qulity prmeters nd ioctive compounds during the cold storge, 1 fruits from ech tree in ech lock for ech tretment were hrvested t the estimted hrvest dtes of ech plum cultivr. The hrvested plums were immeditely plced into crdord oxes in single rows nd trnsferred to the cold storge t ± temperture nd 9±5% reltive humidity (RH) within n hour. Fruits were stored in cold storge for 4 weeks. For ech nlysis period, fruits were selected nd of them were used to determine the fruit qulity chrcteristics (fruit firmness, SS nd T) nd were used to determine ioctive compounds (phenolic nd ntioxidnt ctivity). ioctive compounds were only investigted in fruit flesh. The fruits were nlyzed on, 7 th, 14 th, 21 st, nd 28 th dys of storge. Fifty fruits from ech tree in ech lock of every tretment were stored in crdord oxes in single rows t the estimted hrvest dte of ech plum cultivr to evlute chnge of weight loss (%) nd color chrcteristics (L*, * nd h ) of ech plum cultivr during the cold storge. Physico-mechnicl properties Fruit weights were determined y using digitl lnce (±1 g) (Rdvg PS 45//1, Polnd). Weight loss ws determined y tking the difference etween the initil nd finl weights of ech replicte nd expressed s percent. hromtic nlyses were conducted in ccordnce with the IE (ommission Interntionle de l Eclirge) system of The color chrcteristics (L*, * nd *) of plums were determined with chrommeter (Minolt, model R, Tokyo, Jpn). Vlues of L*, * nd * were used to define three-dimensionl color spce nd interpreted s follows: L* indictes lightness, with vlues rnging from (completely opque or lck ) to (completely trnsprent or white ); positive * vlue indictes redness on the hue circle (-* =greenness) nd positive * vlue indictes yellowness (-* =lueness). The hue ngle (h o ) expresses the color nunce nd vlues re defined s follows: red-purple: ; yellow: 9 ; luish green: 18 ; lue: 27. The chrom (*) is mesure of chromticity, which defines the purity or sturtion of the color. The chrom vlue ws clculted with the formul *= ( *2 + *2 ) 1/2, nd the hue ngle with h = tn -1 * / * (McGuire, 1992). The fruit skin ws cut t two different points (on cheek) over the equtoril prt of the fruit nd the fruit firmness ws mesured y using Effegi penetrometer (model FT 327; Moormick Fruit Tech, Ykim, W) with 7.9 mm tip. The mesurement vlues were expressed s Newton (N). iochemicl chrcteristics In ech nlysis time, fruits were used for ech repliction. Fruits were divided into 4 groups, ech of with 5 fruits, nd 4 different mesurements were otined from ech repliction. The SS of homogente otined from five fruits ws determined with digitl refrctometer (model PL-1, Mcormick Fruit Tech., nd Ykim, Wsh), nd expressed s % solule solids. Titrtle cidity (T, g mlic cid g -1 ) ws determined with ml juice diluted in ml distilled wter, which ws titrted with.1 N NOH to ph of 8.2. totl of ten fruits were homogenized nd plced into 5 different tues ech of hving two fruits nd five different mesurements were tken in ech repliction. The fruit smples were kept in 5 ml tues t - for iochemicl nlysis. Smples were thwed t room temperture ( 21 ) nd homogenized in food grde lender. The resultnt slurry ws centrifuged ( g) for min t 4 to seprte the juice from the pulp. The freshly otined juice mterils were diluted with distilled wter, divided into multiple smple liquots, nd refrozen t - until used in phenolics nd ntioxidnt ssy procedures. Totl phenolics: portion of µl from ech smple ws diluted with 4.3 ml distilled wter nd µl Folin-ioclteu regent were dded. fter n intervl of 3 min, % N 2 O 3 ws dded to µl portions, nd the mixture ws vortexed nd incuted for min. sornces were then red on UV-VIS (PerkinElmer, Lmd 5 spectrophotomer,, US) spectrophotomer t 76 nm. Gllic cid ws used s the stndrd. The results were expressed s mg of gllic cid equivlent per grm of fresh weight (fw) (mg GE g -1 fw), (eyhn et l., ). TS + rdicl scvenging ctivity: 2 mm of TS + (2.2 -zino-is (3-ethyl enzothizoline-6-sulfonic cid) dimmonium slt) nd 2.45 mm of K 2 S 2 O 8 solutions were prepred y.1 M of PO 4-3 uffer solution (ph 7.4). The TS + nd K 2 S 2 O 8 solutions were mixed in (1:2) TS- K 2 S 2 O 8 nd incuted for 6 h in drk. The sornce of the mixture ws red t 734 nm nd it ws diluted with PO 4-3 uffer if the vlue ws greter thn.75. Finlly, µl smples were tken out of the mixture into tues, 1 ml of TS + - K 2 S 2 O 8 solution ws dded to ech tue nd uffer solution ws dded to mke the totl smple volume 4 ml. Following vortexing, they were incuted for min nd sornces were red t 734 nm. The results were expressed s µmol Trolox equivlents (TE) per grm of fw (µmol TE g -1 fw) (Pellegrini et l., 1999). Ferric ions (Fe +3) reducing ntioxidnt power ssy (FRP): Portions of 1 µl were tken from the smples,.2 M of phosphte uffer (PO 4-3 ) (ph 6.6) ws dded to otin volume of 1.25 ml nd then 1.25 ml of 1% potssium ferricynide (K 3 Fe(N) 6 ) solution ws dded. fter vortexing, they were incuted t 5. fterwrds, 1.25 ml of % T (trichloro cetic cid) nd.25 ml of.1% Fel 3 were dded to the smples. The sornces of the resultnt solution were red on n UV-VIS spectrometer t 7 nm. The results were expressed s µmol TE g -1 fw (enzie nd Strin, 1996). 6

3 7 Sttisticl nlysis The normlity of the dt ws confirmed y the Kolmogorov-Smirnov test nd the homogeneity of vrinces y the Levene s test. The dt sets were nlyzed with three-wy NOV y using SS Version 9.3 (SS Institute Inc., ry, N, US) softwre. Duncn multiple rnge test ws used to compre tretments when NOV showed significnt differences mong mens. The level of significnce ws determined t 5%. Results nd Discussion Weight loss (%) mg/l 'lck euty' 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Weight loss (%) mg/l 'lck mer'.4 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time 22 mg/l Weight loss (%) 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 1: hnges in weight loss (%) of lck euty, lck mer nd Fortune plums treted with MeJ, fter cold storge t for 7, 14, 21 nd 28 dys. Ech vlue is men of 15 fruits (5 fruits x three replictions). Vlues followed y different letter in ech period time re significntly different (p<5).

4 mg/l 'lck euty' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy L* hrom Hue ngle mg/l 'lck mer' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy L* hrom Hue ngle mg/l Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy Hrvest 7 Dy 14 Dy 21 Dy 28 Dy L* hrom Hue ngle Figure 2: The effect of MeJ on color chrcteristics (L*, * nd h ) of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter cold storge t for 7, 14, 21 nd 28 dys. Ech vlue is men of 15 fruits (5 fruits x three replictions). Vlues followed y different letter in ech period time re significntly different (P<5).

5 9 Fruit firmness (N) mg/l, MeJ 'lck euty' D D E Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time 6 22 mg/l, MeJ Fruit firmness (N) 5 'lck mer' D D Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time 6 22 mg/l, MeJ Fruit firmness (N) 5 Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 3: The effects of MeJ on fruit firmness of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter cold storge t for 7, 14, 21 nd 28 dys. n=6 for fruit firmness (twenty fruits x three replictions). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5). D

6 SS (%) mg/l, MeJ 'lck euty' 1 4 D Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time mg/l, MeJ 16 'lck mer' SS (%) Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time mg/l, MeJ SS (%) Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 4: The effects of MeJ on SS of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter cold storge t for 7, 14, 21 nd 28 dys.. n= 12 for SS (three replictions x four different mesurements for ech replicte). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5).

7 111 T (g mlic cid ḡ 1 ) mg/l, MeJ 'lck euty' D D Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time T (g mlic cid ḡ 1 ) 22 mg/l, MeJ 'lck mer' D Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time T (g mlic cid ḡ 1 ) mg/l, MeJ Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 5: The effects of MeJ on titrtle cidity (T) of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter cold storge t for 7, 14, 21 nd 28 dys. n= 12 for T (three replictions x four different mesurements for ech replicte). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5).

8 TP, mg GE/g fw mg/l, MeJ Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time 'lck euty' D 112 TP, mg GE/g fw 22 mg/l, MeJ 'lck mer' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time TP, mg GE/g fw 22 mg/l, MeJ Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 6 : The effects of MeJ on totl phenolics (TP) of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter cold storge t for 7, 14, 21 nd 28 dys. n= 15 for TP (three replictions x five different mesurements for ech replictions). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5).

9 TS +, µmol TE/gfw mg/l, MeJ Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time 'lck euty' 113 TS +, µmol TE/gfw mg/l, MeJ 'lck mer' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time TS +, µmol TE/gfw mg/l, MeJ Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 7: The effect of MeJ on totl ntioxidnt ctivity [T, (ccording to TS + )] of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter 7, 14, 21 nd 28 dys t. n= 15 for T (three replictions x five different mesurements for ech replictions). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5).

10 FRP, µmol TE/ g fw mg/l, MeJ 'lck euty' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time D D 114 FRP, µmol TE/gfw mg/l, MeJ 'lck mer' Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time FRP, µmol TE/gfw mg/l, MeJ D D Hrvest 7 Dy 14 Dy 21 Dy 28 Dy nlysis Time Figure 8: The effect of MeJ on totl ntioxidnt ctivity [T, (ccording to FRP)] of lck euty, lck mer nd Fortune plums t the time of hrvest nd fter 7, 14, 21 nd 28 dys t. n= 15 for T (three replictions x five different mesurements for ech replictions). Vlues followed y different lower-cse letter in ech period time re significntly different. Vlues followed y different cpitl letters for ech tretment indicte significnt differences mong nlysis times (P<5). weight loss ws oserved with tretments in ll plum cultivrs during the cold storge period. ompred to control tretment, MeJ significntly reduced the weight loss of lck euty during the cold storge. However, no significnt influence ws oserved in lck mer nd Fortune plums during the storge, except for 14 th dy of storge of lck mer plums (Figure 1). Fruits, in generl, hve considerle resistnce to moisture loss, s their wter vpor pressure is lower thn tht of wter t the sme temperture ecuse of dissolved sustnces, mostly sugrs. The entire weight loss is not due to wter loss lone. Ripening continues fter the hrvest in climcteric or non-climcteric plum cultivrs (Singh nd Khn, ; Pul et l., 12). Respirtion nd ethylene production lso go on during the cold storge nd consequently pectines nd hemicelluloses in cell wlls re roken, structure nd composition of crohydrtes of cell wlls re ltered nd finlly weight loss is oserved in the fruit. In the present study, weight loss in lck euty plum significntly decesed with MeJ tretment. Severity of weight loss is usully relted to storge conditions (temperture, reltive humidity), pre-storge tretments (growth regultors), ripening level of fruits, plnt nutrition, fruit type nd cultivr (Vlero et l., 3; squero nd Guerr, 9; Krishn et l., 12). olor chrcteristics The color chrcteristics (L*, chrom nd hue ngle) of ll plum cultivrs decresed during the cold storge. ompred to control tretment, L* vlues of MeJ-treted Fortune plums were significntly higher t the hrvest nd 7 th dy of storge nd vlues of lck mer plums were

11 significntly higher only t the time of hrvest. hrom vlues of lck euty plums were significntly higher on 14 nd 21 st dys of storge nd vlues of lck mer plums were significntly higher only on 7 th dy of storge. Hue ngle vlues of MeJ-treted lck mer nd Fortune plums were significntly higher thn the control t the time of hrvest nd on 7 th dy of storge nd the vlues of lck euty plums were significntly higher only t the time of hrvest (Figure 2). The color of plum fruit is mostly contriuted y nthocynins nd totl crotenoids. During the mturity nd ripening of plum, nthocynins nd levels of totl crotenoids increse in fruit skin (Singh nd Khn, ). MeJ cuses chlorophyll degrdtion nd stimultes color pigments in unripe fruits (Khn nd Singh 7). distinctive effect of MeJ tretment on colortion of plum cultivrs ws not oserved in current study. ut, positive impcts of MeJ tretments on fruit colortion were reported y Perez et l. (1997) in strwerries, y Rudell et l. (5) in pples, y Jnoudi nd Flore (3) in peches nd y Gonzlez-guilr et l. (3) in ppy. Fruit firmness Flesh firmness of MeJ-treted lck euty, lck mer nd Fortune plums significntly decresed until the 28 th dy of cold storge. However, firmness vlues of MeJ-treted lck euty fruits were significntly higher thn control fruits t hrvest nd on 7, 14 nd 21 st dys of storge, vlues of lck mer fruits were significntly higher on 14 nd 21 st dys of storge nd the vlues of Fortune fruits were significntly higher on 14, 21 nd 28 th dys of storge. On the other hnd, firmness of lck euty fruits on 28 th dy nd Fortune plums on 7 th dy were significntly lower thn the control fruits (Figure 3). Fruit firmness is the most significnt qulity prmeter specifying the mrket vlue nd shelf life of fruits. Producers re le to mrket their products for longer times nd ern more y preserving fruit firmness in cold storges. Krishn et l. (12) reported tht fruit texture ws preserved nd cold storge life ws prolonged with the ppliction of growth regultors efore the hrvest nd storge. Jnoudi nd Flore (3) reported tht MeJ incresed fruit firmness in Redhven pech. ltunts et l. (12) nd Rudell et l. (5) reported the similr results for pples. Gonzlez- guilr et l. (3) reported tht fruit firmness would not e ffected negtively y MeJ tretment during the cold storge. It cn e stted tht the reson why MeJ dose yielded higher fruit firmness thn control in the present study ws due to the fct tht MeJ hd n effect on enzymes tht cuse softening of fruit flesh. Indeed, Fn et l. (1998) reported tht, in reltion to fruit firmness, polyglcturonse iosynthesis ws inhiited y MeJ. ontrrily, Khn nd Singh (7) reported incresing endogenous ethylene levels nd consequent fster ripening of fruits nd incresing enzyme ctivities cusing fruit softening with MeJ tretment in Jpnese plums. In ddition, Kondo et l. (4) indicted different effects of jsmontes for different fruits nd stted tht such effects vried sed on fruit ripening levels, pplied growth regultors, fruit type nd cultivr. Solule solids content SS vlues of MeJ-treted lck euty nd lck mer fruits until 28 th dy of the cold storge nd Fortune plums until 14 th dy of storge significntly incresed. SS vlues of lck euty fruits on entire nlysis periods, lck mer fruits on 14 th dy nd Fortune fruits t hrvest nd on 7, 14 nd 21 st dys of cold storge were significntly lower thn the control fruits (Figure 4). SS vlues increse with incresing ripening levels. Ripened fruits usully hve higher SS levels thn unripe ones. Kondo et l. (1) reported ccelerted ripening effects of MeJ tretments in fruits. In the present study, MeJ negtively ffected SS vlues of ll plum cultivrs during the storge period. Rudell et l. (5) reported retrded conversion of strch into sugr in Fuji pples with MeJ tretments. Possily, MeJ might hve hindered pectin nd polyglctronse enzyme ctivities providing the formtion of glucose, fructose nd sucrose-like sugrs incresing the SS vlues. Or, SS levels might hve een wekened with MeJ tretment through fster ripening of fruits long the enzymtic pthwy to ripening. Titrtle cidity T vlues of MeJ-treted lck euty nd lck mer fruits until 28 th dy of the cold storge nd Fortune plums until 21 st dy of storge significntly reduced. T vlues of MeJ-treted lck euty fruits t hrvest nd on 7 nd 14 th dys of storge, vlues of lck mer plums on 14 nd 21 st dys nd vlues of Fortune plums only on the 7 th dy of storge were significntly lower thn the vlues of control fruits (Figure 5). T of the fruits is ffected y the metolism ctivity especilly respirtion rte which consumed orgnic cid, nd thus the cidity decreses with incresing respirtion rtes. Since the fruits re living things tht respires even fter hrvest from the tree nd during the storge, orgnic cids re continued to e consumed nd thus the cidity decreses (Jn et l., 12). Totl phenolics (TP) nd totl ntioxidnt ctivity (T) TP content of MeJ-treted lck euty plums significntly decresed until 28 th dy of cold storge. On the other hnd, TP vlues of Fortune significntly incresed until 28 th dy of storge. However, TP vlues of lck mer fruits significntly incresed until 21 st dy, then significntly decresed on 28 th dy of cold storge. ompred to control tretment, significntly lower TP contents were oserved in MeJ-treted lck euty fruits t hrvest nd on 7, 14 nd 21 st dys of cold storge, in lck mer plums only on 21 st dy of storge. ontrrily, Fortune plums hd significntly higher vlues thn the control on 14, 21 nd 28 th dys of cold storge (Figure 6). ccording to TS + test, T vlues of MeJ-treted lck euty fruits significntly decresed during the cold storge. On the other hnd, there were significnt increses in T vlues of MeJ-treted lck mer fruits until 21 st dy of storge nd T vlues of Fortune fruits until 14 th dy of storge. ompred to control tretment, significntly lower T vlues were oserved in MeJ-treted lck euty fruits during the cold storge nd in Fortune fruits on 7 th dy of storge. On the other hnd, Fortune fruits hd significntly higher T vlues thn the control on 14 nd 21 st dy of storge (Figure 7). ccording to FRP test, while there were significnt decreses in T vlues of MeJ-treted lck euty fruits until 21 st dy of cold storge, there were significnt increses in T vlues of lck mer fruits until 21 st dy of storge. T vlues of MeJ-treted Fortune fruits lso incresed significntly during the cold storge. ompred to control tretment, significntly lower vlues were oserved in T vlues of MeJtreted lck euty fruits on 7, 14, 21 nd 28 th dys of storge, of lck mer fruits on 21 nd 28 th dys of storge nd of Fortune fruits t hrvest nd on 7 th dy of cold storge. ontrrily, lck euty fruits t hrvest, lck mer fruits on 14 th dy nd Fortune fruits on 21 nd 28 th dy hd significntly higher T vlues thn the control fruits(figure 8). 115

12 Plums re good source of nturlly occurring ioctive compounds [phenolics (neo-chlorogenic cid, p-coumroylquinic cid, chlorogenic cid nd rutin) nd ntioxidnts] (Singh nd Khn, ). There re some chnges in phenolics nd ntioxidnt ctivity of plums during the ripening (Rohwer nd Erwin, 8; Diz-Mul et l., 9). hnges in chemicl composition of fruits including phenolic nd ntioxidnt compounds vry sed on the vriety, growth period, preferred root stock, nutrient contents, environmentl conditions, culturl prctices, ripening levels of fruits, time of hrvest, post-hrvest storge conditions nd post-hrvest fruit processing methods. Some plnt growth regultors (methyl jsmonte, VG, 1-MP, polymines nd nitric oxide) pplied efore nd fter the hrvest nd other implementtions (het tretment, clcium, cold storge) my lso chnge the totl phenolics nd ntioxidnt ctivity of fruits (Joling et l., 3; Khn et l., 7; Singh nd Khn, ; Öztürk et l., 13; Zpt et l., 14). Likewise, with regrd to totl phenolics nd ntioxidnt ctivity, ech plum cultivr of the present study hd different vlues in ech nlysis periods. Different chnges were oserved in TP nd T vlues of plum cultivrs of the present study with MeJ tretments. Kondo et l. (4) reported tht jsmontes hd different effect on ech fruit species nd such n effect depended directly on fruit growth stge nd the concentrtion of pplied plnt growth regultor. Khn nd Singh (7) reported tht ioctive content of fruit could chnge with MeJ tretments. Therefore, MeJ should e studied in detil for different fruit species nd vrieties. Heridi nd isneros-zevllos (9) reported incresed phenolics content of strwerries with MeJ tretments. Diz-Mul et l. (9) found totl phenolics content of different plum vrieties s etween mg GE kg -1 fw. Puert-Gomez nd isneros- Zevllos (11) recorded totl phenolics nd ntioxidnt ctivity of lck Splendor respectively s mg g -1 nd mg g -1 trolox. onclusions In generl, the weight nd firmness losses of plum were significntly delyed with MeJ tretment during the cold storge. ny significnt impcts of pre-hrvest MeJ tretment on color chrcteristics of plum cultivrs were not oserved. MeJ tretment delyed ripening process. The effect of MeJ on phenolics nd ntioxidnt ctivity were sed on plum vriety. MeJ ws proved to e eneficil in extending the cold storge life nd preservtion of the fruit qulity. Future works should include more detiled evlution of key qulity ttriutes such s rom, ioctive compounds nd enzymes, or should focus on trits relevnt to qulity preservtion of plums or other fruits with pre-hrvest MeJ tretment. References 1. ltunts, E., Ozturk,., Ozkn, Y., nd Yildiz, K. (12). Physico-mechnicl properties nd color chrcteristics of pple s ffected y methyl jsmonte tretments. 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