Physiological responses and production of 'Syrah' vines as a function of training systems

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1 Physiologicl responses nd production of 'Syrh' vines 267 Physiologicl responses nd production of 'Syrh' vines s function of trining systems An Crolin Fvero 1 ; Dniel Angelucci de Amorim 2 ; Rent Vieir d Mot 2 ; Cludi Rit de Souz 2 ; Murillo de Albuquerque Regin 2 * 1 UFLA Progrm de Pós-Grdução em Agronomi/Fitotecni, C.P Lvrs, MG Brsil. 2 Núcleo Tecnológico EPAMIG Uv e Vinho, Av. Snt Cruz, Clds, MG Brsil. *Corresponding uthor <murillo@epmigclds.gov.br> ABSTRACT: Plnt rchitecture nd its interction with griculturl prctices nd environmentl constrints is determinnt for grpevine cnopy structure, which is relted to crbon ssimiltion, bud fertility nd fruit qulity. In this context, this study evluted the performnce of field-grown Syrh grpevines conducted by two mngement systems: Verticl Shoot Position () or modified Genev Double Curtin (), in Pirpor, stte of Mins Geris, Brzil, during the winters of 7 nd 8. The evlutions of lef re, wter reltions nd net CO 2 ssimiltion were mde t the end of the ripening period. Yield per vine nd per hectre were estimted nd men berry weight nd dimeter, totl soluble solids, ph nd titrtble cidity were evluted during berry ripening. The grpevines trined in hd higher wter sttus s compred to, shown by differences in pre-dwn lef wter potentil (Ψ pd ) nd stem wter potentil (Ψ stem ). However, the CO 2 ssimiltion ws similr in both trining systems. Fruit exposure ws higher in thn in, which contributed to incresing berry temperture. At hrvest, the berries in reched vlues ner to 23 ºBrix wheres berries in showed vlues ner 21 ºBrix. Key words: CO 2 ssimiltion, cnopy mngement, wter potentil, berry temperture, fruit qulity Respost fisiológic e produção do vinhedo de 'Syrh' em função dos sistems de condução RESUMO: A rquitetur d plnt e su interção com prátics gronômics e vriáveis mbientis determinm estrutur do dossel vegetl, que está envolvid n ssimilção de crbono, fertilidde ds gems e qulidde d frut. Neste contexto, vliou-se o comportmento de um vinhedo de Syrh conduzido nos sistems espldeir () e Dupl Cortin de Genev modificdo (). As vlições d superfície folir primári, relções hídrics e ssimilção líquid de crbono form relizds no finl do período de mturção d uv. Foi feit estimtiv d produção por plnt e por hectre e vlidos o peso e diâmetro ds bgs e teores de sólidos solúveis, ph e cidez titulável durnte o mdurecimento ds bgs. As plnts conduzids em espldeir presentrm melhor hidrtção, sendo observds diferençs no potencil hídrico d folh (Ψ pd ) e do cule (Ψ stem ). A ssimilção líquid de CO 2 não foi fetd pelos sistems dotdos, e redução no Ψ pd e Ψ stem observd no sistem não lterou tx fotossintétic. A exposição d frut foi mior no sistem em espldeir, o que contribuiu pr umento n tempertur ds bgs. N colheit, s bgs do sistem tingirm vlores próximos 23 ºBrix, enqunto no sistem em espldeir, os vlores não pssrm de 21 ºBrix. Plvrs-chve: ssimilção de CO 2, mnejo de dossel, potencil hídrico, tempertur d bg, qulidde dos frutos Introduction Light interception nd plnt microclimte within cnopy, prticulrly in the fruit zone re mong the most importnt determinnts of grpe berry composition (Jckson nd Lombrd, 1993). Sun exposed berries hve higher concentrtion of sugrs, orgnic cids, nthocynins nd rom compounds (Smrt, 1985; Reynolds et l., 4). However, excessive bunch exposure results in low cid contents nd undesirble wine roms (Jckson nd Lombrd, 1993). Furthermore, high temperture during berry ripening my inhibit nthocynin synthesis or increse nthocynin degrdtion (Hselgrove et l., ). In ddition, there is lso reltionship between trining system, root distribution nd lef surfce re, which hve impcts on vine wter sttus (Deloire et l., 4). Grpe growth nd berry biochemicl composition re closely linked to vineyrd wter sttus, nd to cnopy nd grpe bunch microclimte (Ojed et l., 1; Souz et l., 5; Sntos et l., 5). Pirpor, locted in the North of the stte of Mins Geris, Brzil, is trditionl region for tble grpe production. The wether conditions (tropicl climte with dry period nd sub-humid condition throughout the yer) llow the growth of grpevines of the Vitis vinifer species, including tble nd wine grpes nd it my contribute to expnd the winemking industry in Mins Geris. The climte conditions lso llow the vines to

2 268 Fvero et l. produce grpes in two different cycles per yer, one cycle from August/September to Jnury/Februry (the normlly cycle dopted in most growing regions of Brzil) clled summer cycle, nd the other, from Februry to July, clled winter cycle. This lst cycle hs n dvntge upon the summer cycle becuse the mturtion period nd hrvest coincide with the drier period of the yer ssocited with lrger therml mplitude. However, there is no informtion in the literture bout the mngement of vineyrds to produce high qulity wine under these tropicl conditions. In this context, this study evluted the vine performnce of field-grown Syrh grpevines under different trining systems. The knowledge of how grpevines respond to different trining systems will result in better control of vegettive growth, yield nd must composition, nd will lso contribute to improve the vineyrd mngement in tropicl regions such s Northern Mins Geris. Mteril nd Methods This study ws crried out in n irrigted experimentl vineyrd locted in Pirpor, North of Mins Geris stte, Brzil (17 21 S, W) t n ltitude of 5 m. The tropicl humid regionl climte is clssified s Aw ccording to Köppen, with dry seson during the winter. The nnul verge rinfll is 1, mm, with 2,695 sunshine hours. The nnul verges of mximum temperture nd reltive humidity re 3.6ºC nd 7.9%, respectively, nd the therml mplitude, bsed on its monthly verges is 12.7ºC incresing up to 16.1 C during the hrvest period (Tonietto et l., 6). The evlutions were performed during the ripening period of July of 7 nd 8, corresponding to the winter growing seson, in.2h vineyrd (48 plnts) of Syrh (clone 174) grfted onto 113 Pulsen rootstock, plnted in Februry 6. The irrigtion mngement consisted of drip irrigtion nd the mount of wter pplied ws clculted from the verge evpotrnpirtion (4. mm dy 1 ). From bud burst to the beginning of the mturtion period 15 L h 1 per plnt were pplied three times week nd, during the mturtion period, the sme quntity of wter ws pplied but only once week, until one week before the hrvest. Production pruning consisted of spur pruned vines with two nodes in length performed in Februry 7 nd 8 in lignified shoots formed during the growing seson from September 6 to Februry 7 nd September 7 to Februry 8. The vines were spced 2.8 m between rows nd 1.5 m within rows, t North- South orienttion. Two mngement systems were tested: Verticl Shoot Position () nd modified Genev Double Curtin () (Figure 1). In the system, the vines were trined on bilterl Royt Cordon t 1. m boveground with shoots positioned upwrds in three folige wires (1. m of surfce re). In the system, the trunk ws 1.9 m height nd the shoots were horizontlly divided nd trined downwrds. The curtins were supported t the top nd the shoots were positioned to void n excessive light exposure on the fruit zone. Stndrd culturl prctices in the region were pplied to both tretments during the growing sesons. Figure 1 - (A) Verticl shoot positioned () trellis nd (B) Genev Double Curtin () trellis, in Pirpor, Mins Geris, Brzil (winter 7 nd 8).

3 Physiologicl responses nd production of 'Syrh' vines 269 The evlutions of primry lef surfce, wter reltions nd net CO 2 ssimiltion were performed t the end of the ripening period, two weeks before hrvest, in rndomized complete design. The primry lef surfce ws clculted ccording to Crbonneu (1976 nd 1977, cited by Regin et l., ) for ten grpevines per tretment. The vine wter sttus ws evluted in the field through mesurements of pre-dwn lef wter potentil (Ψ pd ), middy lef wter potentil (Ψ md ) nd stem wter potentil (Ψ stem ), mesured with Scholnder-type pressure chmber (Soil moisture Equipment Corp., model 35). Mesurements were mde on six fully expnded leves from different vines per tretment. Ech removed lef from the vine ws immeditely evluted to void wter loss. The Ψ pd ws mesured before sunrise, the Ψ md mesured t middy, nd Ψ stem ws mesured between 14h nd 15h. The Ψ stem ws mesured ccording to Choné et l. (1) on non-trnspiring leves, which hd been bgged with both plstic film nd luminum foil 3 hours before mesurements. CO 2 ssimiltion rte (A) ws mesured in two periods in the morning, t 9h nd 12h on the sme dy tht wter potentils were mesured. Six fully expnded nd completely exposed leves situted in the medium portion of the stems were used for the mesurements with portble infrred gs nlyzer (model CID 31 PS, working in n open system). The mesurements were tken with PAR bove 9 μmol m 2 s 1. One dy before hrvest, forty berries fcing west nd est ( berries per fce) were selected for temperture mesurements. Berry temperture ws mesured t 8h, 1h, 12h, 14h nd 16h with portble thermometer (Instrutherm, model TE-3). At hrvest, the number nd weight of bunches were recorded in ll vines nd lso used to estimte yield per vine nd per hectre. Men berry weight ws estimted from smple of 1 berries while the dimeters (trnsversl nd longitudinl) were estimted from smple of berries. A smple of 21 berries divided into three replictes were crushed in polyethylene bg nd filtered. The resulting juice ws immeditely nlyzed for totl soluble solids (TSS; ºBrix) with portble refrctometer (ATAGO model PAL 1), nd the ph of undiluted juice of ech smple ws determined using ph meter, nd titrtble cidity (TA) ws determined by titrtion of diluted juice with.1 mol L 1 of NOH to phenolphthlein end point nd expressed s g L 1 trtric cid. Sttisticl dt nlysis ws performed by nlysis of vrince (ANOVA) using the ESTAT softwre. The sttisticl differences were detected by the F test. Results nd Discussion Grpevines trined in were in higher wter sttus thn in the s shown by differences in predwn lef wter potentil (Ψ pd ) during both yers, nd stem wter potentil (Ψ stem ) during the 7 seson (Tble 1). The Ψ pd nd Ψ stem hve been considered in the literture s good wter stress indictors for vines (Deloire et l., 4). Moreover, the Ψ stem cn be powerful tool to ssess vine wter sttus since it is less ffected by shortterm fluctutions induced by stomtl behvior nd environmentl conditions s compred to Ψ md (Choné et l., 1). Despite the differences for Ψ pd vlues of the 7 seson, they were bove -.2 MP in both mngement systems, which is in the rnge considered s bsence of wter stress, wheres in 8 seson the vlues were round -.4 MP, considered s mild wter stress (Deloire et l., 4). The differences between sesons my be explined by evpotrnspirtion nd by the intervl between irrigtion nd mesurements of pre-dwn lef wter potentil. The mesurements of Ψ pd in 8 were mde some dys fter irrigtion while in 7 immeditely fter irrigtion. Furthermore, the lowest ir temperture in 8 (28ºC t 9h nd 34ºC t middy) s compred to 7 (3ºC t 9h nd 36ºC t middy) nd lowest lef temperture in 8 (29ºC t 9h nd 34ºC t middy) s compred to 7 (35ºC t 9h nd 39ºC t middy) lso could hve contributed to increse the vlues of Ψ stem in 8. The decrese in vine wter sttus of the system could be ttributed to greter lef re resulting in incresed wter loss observed in this trining system (Tble 2). Plnt wter sttus my be ffected by chnges in lef specific hydrulic conductnce due to its effect on stomtl conductnce (Hubbrd et l., 1; Schultz, 3; Smrt et l., 6). Furthermore, the greter trunk height in system (1.9 m) s compred to (1. m) nd lso the differences in brnch orienttion could hve contributed to hinder wter trnsport to the grpevine cnopy. Schubert et l. (1999) showed tht shoot hydrulic conductivity is negtively ffected by downwrd brnch orienttion in contrst with upwrd growing Tble 1 Effect of trining system on pre-dwn (Ψ pd ), middy lef wter potentil (Ψ md ) nd stem wter potentil (Ψ stem ) of Syrh grpevines in Pirpor, Mins Geris, Brzil (winter of 7 nd 8). Vlues re verges ± SD. Averges followed by different letters in the sme row per seson re different (p <.5). Wter Potentil (MP) Pre-dwn Middy ( lef Ψ p d ) ( Ψ m d ) Stem ( Ψ s tem ) ±.17 b -1. ± ± ±.44 SD Stndrd devition ±.4 b -.7 ± ±.2 b -.38 ± ± ± ± ±.11

4 27 Fvero et l. brnches. Shoot downwrd orienttion induces ccumultion of uxin in the pex nd this ffects the density nd the size of the xylem vessels, cusing reduction of hydrulic conductivity (Lovisolo t l., 2). CO 2 ssimiltion rte (A) of Syrh ws not ffected by the trining systems in both mesured periods (Tble 2). The reduction in Ψ pd nd Ψ stem observed in vines did not ffect the photosynthesis rte. Although Ψ pd reched vlues round -.4MP, considered moderte wter stress (Deloire et l., 4), the photosynthesis ws unffected s shown by other uthors for grpevine (Souz et l., 5b) nd other crop species (Fereres nd Sorino, 7). The differences between sesons of CO 2 ssimiltion rtes were probbly due to wether conditions (tempertures) during gs exchnge mesurements, s explined bove for results of lef wter potentil. In generl, in both growing sesons, the berries of the system hd the highest tempertures s compred to in most of the mesured time (Figure 2). Tble 2 Effects of trining systems on brnch number, yield components, primry lef surfce nd CO 2 ssimiltion rte (A) of Syrh grpevines in Pirpor, Mins Geris, Brzil (winter 7). The vlues re verges ± SD. Averges followed by different letters re different (p <.1) nd (p <.5)*. Number Number of brnches per vine of bunches per vine SD Stndrd devition ± ± 2.28 b 22.8 ± ± 3. b 22.1 ± ± 4.2 b 37.6 ± ± 6.96 b Berry weight (g) Trnsversl dimeter Longitudinl dimeter (mm) (mm) 13.8 ± ±.91 b ± ±.79 b ± ±.81 b ± ±.95 b 1 Y ield (kg vine ) 3.17 ± ±.11 b 5.31 ± ±.94 b 1 E stimted yield (kg h ) 7.6 ± ±.27 b 12.6 ± ± 2.25 b Primry lef surfce (m 2 )* 3.9 ± ±.34 b 4.29 ± ±.85 b 2 Lef re /fruit weight (m kg 1) 1. ±.7 b 1.35 ±.7.82 ± ±.22 2 A (μmol m s 1 )* 9h 9.38 ± ± ± ±.83 12h 6.2 ± ± ± ± Est 8 Est Berry Temperture ( C) b b b Berry Temperture ( C) b b b * West 8 West Berry Temperture ( C) b b b b * Figure 2 - Effect of trining systems on berry temperture mesured from 8h to 16h in the Est nd West fces of the Syrh grpevine. Pirpor, Mins Geris, Brzil (winter 7 nd 8). Vlues re verges ± SD (Stndrd Devition). p <.1, except with * tht p <.5. Berry Temperture ( C) b * b

5 Physiologicl responses nd production of 'Syrh' vines 271 The berries of the system only presented highest tempertures t noon in both fces in 7, nd in 8 t 16h in the Est fce nd t 1h in the West fce. Fruit exposure ws greter in thn in, contributing to increse berry temperture. However, in 7 t middy, the berries in the system hd higher tempertures, probbly due to the upwrd position of the leves of this system tht exposed the bunches to higher full solr rdition. Grpevines trined by hd greter shoot number nd yield thn those of the system in both yers (Tble 2). Yield ws greter for due to greter bunch number, nd lso due to incresed berry dimeters (trnsversl nd longitudinl). The greter yield of grpevines for (7.6 ton h 1 in 7 nd 12.6 ton h 1 in 8) in contrst to the system (4. ton h 1 in 7 nd 8.5 ton h 1 ) did not negtively ffect berry soluble sugr ccumultion (Figure 3). At hrvest, the berries of reched vlues ner to 23 ºBrix nd 21 Brix, in 7 nd 8, respectively, wheres those for hd vlues round 21º Brix in both yers. The explntions for this result is tht most of the sugr lod in the berries re derived from plnt crbon ssimiltion (Ruffner et l., 1995; Dvis nd Robinson, 1996), which is dependent on the totl mount of exposed lef re. Although there were no differences in photosynthetic rtes between trellis-trining systems (Tble 2), the lef re for ws higher s compred to (Tble 2) nd my hve contributed to increse the totl crbon ssimiltion of grpevine trined under the system. In ddition, since the type of trellis-trining system used hs such dominnt influence on the mount of lef re Soluble solids ( Brix) Soluble solids ( Brix) Titrtble cidity (g L 1 ) Titrtble cidity (g L 1 ) ph Figure 3 Effects of trining systems on soluble solids, titrtble cidity nd ph in must of Syrh grpevines during the ripening periods of 7 nd 8. The vlues re verges ± SD. ph

6 272 Fvero et l. exposure, the optiml lef re/fruit weight rtio of single- nd divided-cnopy trining systems could lso explin the obtined results. In fct, there were significnt differences between trining systems for the proportion lef re nd fruit weight only in 7. For, vines hd 1. m 2 lef re per kg fruit, wheres for, this rtio incresed to The lef re/fruit weight rtio hs been used s mesure of crop lod nd vine blnce for the production of high qulity wine. The vlues found in this study were bove the rnge considered s indictive of well-blnced vines (not over or under cropped) by some uthors. Kliewer nd Dokoozlin (5) showed tht the lef re required for mximum level of soluble sugr, berry weight nd berry colortion t hrvest should be within the rnge of.5 to.8 nd.8 to 1.2 m 2 per kg for nd, respectively. However, the rtio below which sugr level strts to decline ws lso reported by Jckson nd Lombrd (1993) nd Willims (1996) to be between.7 nd 1. m 2 per kg. Vlues given in the literture for the mount of lef re needed to support unit weight vry considerbly depending on the cultivr, climtic region nd method of mesurement. In the present study, sugr contents observed for berries of ws greter thn those of only in the 7 seson, suggesting tht vines were better blnced in 7. Probbly, in the under cropped vines there ws more competition by photossimiltes between fruits nd growing brnches (nd roots), contributing to decrese sugr concentrtion (Nor et l., 1997). Furthermore, divided cnopy trining systems such s hve considerbly higher percentge of their lef re t light sturtion in contrst to single cnopy systems, nd, therefore, lower lef re/fruit weight rtio for fruit mturtion would be expected (Kliewer nd Dokoozlin, 5). Despite the differences observed in soluble solids only in 7, ph nd titrtble cidity did not chnge between trining systems in the two evluted sesons (Figure 3). Berry composition is ffected by exposure to sunlight through temperture nd incident rdition. The incresed temperture by excessive bunch exposure my produce berries with lower ph nd greter cidity due to mlic cid degrdtion s shown by some uthors (Ruffner, 1982; Smrt nd Robinson, 1991; Jckson nd Lombrd, 1993). However, in this experiment, the highest berry temperture observed for vines in the morning hd no negtive impct on totl cidity. Similr results were lso obtined by Crippen nd Morrinson (1986) compring shded nd sun-exposed fruits. Acknowledgements To thnk FAPEMIG, CAPES nd CNPq for finncil support, the Coopertiv Agrícol de Pirpor nd Associção dos Usuários do Projeto Pirpor for providing the grpevines for this study nd Lênio Grcino Prdo for drwing Figure 1. References Choné, X.; Vn Leeuwen, C.; Dubourdieu, D.; Gudillère, J.P. 1. Stem wter potentil is sensitive indictor of grpevine wter sttus. Annls of Botny 87: Crippen, D.D.; Morrinson, J.C Effects of sun exposure on the compositionl development of Cbernet Suvignon berries. Americn Journl of Enology nd Viticulture 37: Dvis, C.; Robinson, S.P Sugr ccumultion in grpe berries. Plnt Physiology 111: Deloire, A.; Crbonneu, A.; Wng, Z.; Ojed, H. 4. Vine nd wter: short review. Journl Interntionl des Sciences de l Vigne et du Vin 38: Fereres, E.; Sorino, M.A. 7. Deficit irrigtion for reducing griculturl wter use. Journl of Experimentl Botny 58: Hselgrove, L.; Botting, D.; Vn Heeswijck; Hoj, P.B.; Dry, P.R.; Ford, C.; Ilnd, P.G.. Cnopy microclimte nd berry composition: the effect of bunch exposure on the phenolic composition of Vitis vinifer L. cv. Shirz grpe berries. Austrlin Journl of Grpe nd Wine Reserch 6: Hubbrd, R.M.; Ryn, M.G.; Stiller, V.; Sperry, J.S. 1. Stomtl conductnce nd photosynthesis vry linerly with plnt hydrulic conductnce in ponderos pine. Plnt, Cell nd Environment 24: Jckson, D.I.; Lombrd, P.B Environmentl nd mngement prctices ffecting grpe composition nd wine qulity: review. Americn Journl of Enology nd Viticulture 44: Kliewer, W.M.; Dokoozlin, N.K. 5. Lef re/crop weight rtios of grpevines: influence on fruit composition nd wine qulity. Austrlin Journl of Enology nd Viticulture 56: Lovisolo, C.; Schubert, A.; Sorce, C. 2. Are xylem rdil development nd hydrulic conductivity in downwrdlygrowing grpevine shoots influenced by perturbed uxin metbolism? New Phytologist 156: Nor, A.; Gl, Y.; Brvdo, B Crop lod ffects ssimiltion rte, stomtl conductnce, stem wter potentil nd wter reltions of field-grown Suvignon blnc grpevines. Journl of Experimentl Botny 48: Ojed, H.; Deloire, A.; Crbonneu, U.A. 1. Influence of wter deficits on grpe berry growth. Vitis 4: Regin, M.A.; Pereir, G.E.; Cnçdo, G.M.A.; Rodrigues, D.J.. Clculte of the lef re on grpevine through nondestructive method. Revist Brsileir de Fruticultur 22: (in Portuguese, with bstrct in English) Reynolds, A.G.; Wrdle, D.A.; Cliff, M.A.; King, M. 4. Impct of trining system nd vine spcing on vine performnce, berry composition, nd wine sensory: ttributes of seyvl nd chnce. Americn Journl of Enology nd Viticulture 55: Ruffner, H.P Metbolism of trtric nd mlic cids in Vitis: review; Prt B. Vitis 21: Ruffner, H.P.; Hürlimnn, M.; Skrivn, R Soluble invertse from grpe berries: purifiction, deglycosyltion nd ntibody specificity. Plnt Physiology nd Biochemistry 33: Sntos, T.P.; Lopes, C.M.; Rodrigues, M.L.; Souz, C.R.; Silv, J.M.R.; Mroco, J.P.; Pereir, J.S.; Chves, M.M. 5. Effects of prtil rootzone drying irrigtion on cluster microclimte nd fruit composition of field-grown Cstelão grpevines. Vitis 44: Schubert, A.; Lovisolo, C.; Peterlunger, E Shoot orienttion ffects vessel size, shoot hydrulic conductivity, nd shoot growth rte in Vitis vinifer L. Plnt, Cell nd Environment 22: Schultz, H.R. 3. Differences in hydrulic rchitecture ccount for ner-isohydric nd nisohydric behviour of two field-grown Vitis vinifer L. cultivrs during drought. Plnt, Cell nd Environment 26:

7 Physiologicl responses nd production of 'Syrh' vines 273 Smrt, D.R.; Brezele, A.; Zufferey, V. 6. Physiologicl chnges in plnt hydrulics induced by prtil root removl of irrigted grpevine (Vitis vinifer cv.syrh). Americn Journl of Enology nd Viticulture 57: 1-9. Smrt, R Principles of grpevine cnopy microclimte mnipultion with implictions for yield nd qulity: review. Americn Journl of Enology nd Viticulture 36: Smrt, R.; Robinson, M Sunlight Into Wine: A Hndbook for Winegrpe Cnopy Mngement. Ministry of Agriculture nd Fisheries, Wellington, New Zelnd. Souz, C.R.; Mroco, J.P.; Sntos, T.P.; Rodrigues, M.L.; Lopes, C.M.; Pereir, J.S.; Chves, M.M. 5. Grpe berry metbolism in field-grown grpevines exposed to different irrigtion strtegies. Vitis 44: Souz, C.R.; Mroco, J.P.; Sntos, T.P.; Rodrigues, M.L.; Lopes, C.M.; Pereir, J.S.; Chves, M.M. 5b. Control of stomtl perture nd crbon uptke by deficit irrigtion in two grpevines cultivrs. Agriculture, Ecosystems nd Environment 16: Tonietto, J.; Vinello, R.L.; Regin, M.A. 6. Mcroclimtic crcteriztion nd enologicl potentil of different regions with viticulturl ptitude in Mins Geris. Informe Agropecuário 27: 2-55 (in Portuguese). Willims, L.E Grpe. p In: Zmski, E.; Schffer, A.A, eds. Photossimilte distribution in plnts nd crops: source-sink reltionships. Mrcel Dekker, New York, NY, USA. Received December 19, 8 Accepted Jnury 8, 1