Composition of Sauvignon Blanc Grapes As Affected by Pre-Veraison Canopy Manipulation and Ripeness Level

Composition of Sauvignon blanc Grapes as Affected by Pre-veraison Canopy Manipulation and Ripeness Level

J.J. Hunter*, C.G. Volschenk, J. Marais and G.W. Fouche ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, South Africa Submitted for publication: June 2003 Accepted for publication: March 2004 Key words: Grapevine, Sauvignon blanc, canopy management, suckering, shoot positioning, topping, leaf thinning, yield, grape composition, ripeness level

The implications of pre-veraison canopy management and ripeness level (19°B and 21 °B) on microclimate and grape and must composition were determined on intensively micro-sprinkler irrigated Vitis vinifera L. cv. Sauvignon blanc/110 Richter vines, grown on a vertical trellis in the Breede River Valley of South Africa. Rows were y Canop . apart m c 5 1 y approximatel d space e wer s Spur . m 5 1. x m 5 2.7 d space s vine d an d orientate t east-wes management consisted of different combinations of seasonal practices (suckering, shoot positioning, topping, leaf thinning) during the pre-veraison growth period (just after budding to pea size berry) in order to accommodate foliage and to improve the canopy microclimate. Treatments that included leaf thinning improved the light conditions in the canopy without a noticeable effect on other microclimate parameters as well as bunch and berry sap temperature. The must pH remained relatively stable, with an increase in ripeness level from 19°B to 21°B, whereas the rest of the measured grape composition components followed a decreasing pattern during this period. Treatments that included leaf thinning tended to increase titratable acidity and decrease pH at both ripeness levels. Additional leaf thinning (up to the lower half of the canopy at pea size) increased the glucose and fructose concentrations without changing their ratio. It also decreased the malic acid concentrations of the berries, whereas the free-amino-nitrogen content of the must was stimulated. Furthermore, leaf thinning in general increased the monoterpene content (fruity aroma) and apparently enhanced the 2-methoxy-3-isobutylpyrazine content (grassy/green pepper aroma), thereby increasing the total measured aroma profile. Both palate and flavour profiles were therefore changed by applying pre-veraison seasonal canopy management. The data emphasised the importance of the correct timing and application of canopy management. This seemed to be of great significance in the realisation of an improved grape composition, even for S. blanc subjected to a relatively hot terroir.

It is well known that macro/meso-climate affects grape composi- improved light distribution in the canopy. Judicious changing of tion and wine quality (Coombe, 1987, 1989). The sensitivity of the physical appearance of the canopy also has physiological the nitrogen-containing 2-methoxy-3-isobutylpyrazine (ibMP) implications that virtually always comprise a change in the compound, typically occurring in cultivars such as Sauvignon source:sink relationships in the grapevine and a simultaneous blanc, Cabernet Sauvignon and Semillon (Lacey et al., 1991) improvement in photosynthetic activity and export of photo- under conditions of high light intensity and/or high temperature, assimilates from leaves to sinks such as the berries (Johnson et has already been shown (Lacey et al., 1991; Alien & Lacey, 1993; al., 1982; Hunter & Visser, 1988a, 1988b, 1988c; Candolfi- Marais et al., 1999). The resulting reduction in grassy/green pep- Vasconcelos & Koblet, 1990; Hunter et al., 1995; Koblet et al., per-like aroma of the wine is a matter of concern to growers and 1996). Marrying the canopy microclimate required for the winemakers, particularly in the case of S. blanc. improvement of viticulturally-essential parameters - such as bud The value of canopy management for obtaining and improving burst, bud fertility, disease control, the accumulation of well- grape and wine quality in vineyards where it is required, because known quality-determining compounds (e.g. sugars, organic of injudicious long- and short-term decisions during establish- acids, amino acids, phenolics, monoterpenes) and berry pH with ment and cultivation, has been shown unequivocally (Kliewer et a sufficient, quality-contributing occurrence of typical character al., 1988; Koblet, 1988; Candolfi-Vasconcelos & Koblet, 1990; in the grapes of particularly S. blanc remains a challenge under Smart et al, 1990; Stapleton & Grant, 1992; Hunter et al., 1995; different environmental and cultivation conditions. Hunter, 2000; Volschenk & Hunter, 2001a, 2001b). Since canopy In this study the effect of judicious canopy management as well management (along with pruning, training and trellising) is pri- as ripeness level on the presence of some flavour- and palate- marily focused on altering canopy components (shoot position determining compounds in S. blanc grapes produced in a rela- and orientation), the microclimate that the grapes are subjected to tively hot terroir was investigated. The study was also aimed at during development is also changed, mostly in favour of elucidating the importance of creating improved metabolic func-

*Corresponding author: E-mail address: [email protected] Acknowledgements: D.J. le Roux, E. Fourie, L.F. Adams, W.J. Hendricks and Personnel of the Robertson Experiment Farm for technical assistance and the South African vine and wine industry (through Winetech) for financial support.

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13 14 Sauvignon blanc Grape Composition

pre-veraisoe th g . durin nperiod s grape d an s leave tionin e th f go s ("Balling)solid H ,s g/p titratabl(a Ld y tartarian ) eacidit cacid Indicationg s are thaconsistin e t eventsampl s durinh bunc g e this period marepresentativ a y bm e criticafro d l in the determine e wer determination of eventual grape and wine qualit. y (Carbonneabunches n seve u t & leas t a f o Deloire, 2001; Hunter & Archer, 2001, 2002; Ojeda et al., 2002). Malic, tartaric and citric acid as well as glucose and fructose S METHOD D AN S MATERIAL s a d performe e wer C HPL y b s analyse d an s berrie m fro n extractio viticulturad s an d lpractice Vineyar described by Hunter et al. (1991). Grape monoterpene and ibMP n d VitisSauvigno vinifera. cv 10-year-ol . L s vigorou y visuall A extractions and analyses by means of GC and GC-MS were done blanc (clone SB 10) vineyard- , monoter grafte l d ontindividua oe 110 RichteRelativ . r (clon(1996) Maraio t g al. eset accordin et s Marai y b d describe s a d summarise e wer s concentration e pen RQ28A), and situated in the Robertson region (semi-arid Breede g (1999)al. accordin d . Free-amino-nitrogedetermine s wa ) n(FAN River Valley of the Western Cape - Winkler Region IV) (Hunter - refer s a e sulphat m ammoniu g usin d metho r Analyse o Aut n a o t g Workin n Classificatio l Bonnardot Huttoa & (Soi n l o ) nsoi ,2002 Group, 1991) was used. Vine rows were orientated approximate- ence (Anonymous, 1974). n cordo d an m 5 1. x m 5 2.7 d space , south-west o t t north-eas y l Statistical layout and analyses trained to a Lengthened Perold (Vertical Shoot Positioned) Treatments were replicated five times with five vines per replicate System (Zeeman, 1981). Two-bud spurs were spaced 15 cm apart. in a randomised block design and applied for three years. Buffer Intensiv. e micro-sprinklelayout l r irrigatioexperimenta e th n ni wad s appliedinclude t no . e wer s vine d an s row Treatments Mean values of the last two years of the experiment (1994/95 and Three treatments comprising different combinations of seasonal 1995/96) are presented. Student's t-LSD test was used to deter- ) suckering1 : t shoo ,applied e wer s practice t managemen y canop . differences t significan e min f lea , topping , positioning t shoo , suckering ) 2 ; topping , positioning RESULTS AND DISCUSSION f lea , topping , positioning t shoo , suckering ) 3 ; set y berr t a g thinnin thinning f lea d include t tha s treatment t managemen y Canop thinning at berry set and pea size. Treatments were harvested at , this f o e spit n I . 1) e (Tabl y canop e th n i s condition t ligh d increase ripeness levels of 19°B and 21°B, respectively. Shoot positioning other microclimate parameters (temperature, relative humidity, - correspond h wit e lin n i s shoot f o g positionin l vertica f o d consiste air flow) as well as bunch and berry sap temperature were large- ing spurs. Suckering consisted of the removal of shoots not located t tha y canop a n i d resulte g thinnin f lea m rando e Th . unaffected y l on spurs at approximately 30 cm main shoot length. Topping (30 s leave r interio e th t tha y wa a h suc n i e penetrat o t t sunligh d allowe cm above the top wire) was done twice during the period berry set and bunches received diffused (filtered) sunlight, which was , shoots f o m c 0 3 o t p u f o l remova e th d entaile d an e siz a pe o t recognised in the vineyard by the canopy shadow having small, resulting in a remaining primary shoot length of approximately 1.4 . 1990a) , Visser & r (Hunte s sun-fleck d distribute y evenl e th n i e sid o t e sid m fro y evenl e don s wa ) (33% g thinnin f Lea . m canopy on all leaves, i.e. on primary and secondary shoot leaves Average yield and bunch rot amounted to 15.8 ton/ha and 0.6%, d consiste g thinnin g durin d remove s leave f o % 30 y (approximatel . treatments n betwee s difference t significan o n h wit , respectively of leaveh s situatewit d d on decrease latera t l shoots)conten N FA , s aa tl eithewel s ra berry y seacidit te or at berrtitratabl t y mus e Th f lea , set y berr t A . al.,et 1995) r (Hunte s stage y berr e siz a pe d an t se t no s wa H p s wherea , 19°m 21°B Bo t fro s ripenes n i e increas n a thinning was done in the bunch zone and at pea size berry, thinning affected during this period (Table 2). Leaf thinning tended to was done in the bottom half of the canopy above the bunch zone. increase the titratable acid content and decrease pH at both Canopyy measurementberr e siz a pe t sa g thinnin f lea l additiona n A . levels s ripenes increased the FAN content of the must, resulting in a higher - dur d measure s wa y canop e th f o e zon h bunc e th n i y intensit t Ligh FAN:°B ratio. The presence of amino acids is generally consid- a LICO f e o s RLin mean y b ) 10:00 m (fro g mid-mornin g in ered to be favourable to fermentation and flavour development in Quantum Sensor and expressed as a percentage of ambient light wine (Rapp & Versini, 1996). The glucose and fructose content of n i e temperatur d an w flo r Ai . row e vin e th n i d determine y intensit the berries decreased with an increase in ripeness (Table 3). This the bunch zone were measured using a Kane-May 4003 thermo- most probably resulted from an increase in berry volume, a pos- anemometer, whereas relative humidity was measured with a sible reduction in sucrose production because of leaf senescence s wa e temperatur p sa y Berr . meter y humidit 0 800 y Kane-Ma and a reduced sink capacity of the berry (Hunter & Ruffner, determines d insidberrie e th e tho t es intacleave t e berrth ym anfro d e bunchsucros f temperaturo n e waTranslocatio s . 2001) determined inside the bunch between the berries by using -an ETI would therefore also have been affected at the later stage of 2202 thermometer fitted with a probe. Berries and bunches were ripeness. An additional leaf thinning at pea size had a stimulating randomlg y selectedindicatin . , The probhexoses eo watw se insertethes f o d inte o the puloccurrenc pe oth f thn eo t effec berry. s Canopleave ye th densit m yfro n was determinetranslocatio e d aftesucros rd than en point functio quadra f lea d t enhance - per e wer s measurement l Al . (1982) t Smar y b d describe d metho , 2001). Ruffner & r (Hunte s and/oberrie e th r n invertasi y eactivit y randoml e thre t leas t a n i t harves e befor y immediatel d forme y b d increase e b o t n know s i s photosynthetie Th leave f o y cactivit d an s gap y canop e percentag e Th . replicate r pe s position d selecte - precur l essentia e ar s Carbohydrate . 2000) , (Hunter g thinnin f lea bunch exposure was visually scored for every replicate according sors for the formation of secondary compounds and availability is to a score card based on that of Smart et al. (1990) (Hunter, 1999). therefore critical. As expected, individual organic acid concentra- Yield - componentaddi n A . s3) e (Tabl g ripenin n i e increas n a h wit d decrease s tion Yield values represent total yield from all replications per treat- tional leaf thinning at pea size reduced the malic acid concentra- e solubl d an y da e sam e th n o d harveste e wer s Treatment . ment tion in the berry, leading to a higher tartaric acid:malic acid ratio.

S. Afr. J. Enol. Vitic., Vol. 25, No. 1, 2004 Sauvignon blanc Grape Composition 15

- man y canop e th f o e cas e th n i H p r lowe y apparentl e th n Give e increas o t n know s e (Seftoi ) al.,profil net 1994 a arom e th o t agement treatments that included leaf thinning, this may indicate upon improved sunlight exposure of the grapes (Marais et al., f o s grape e th o t e translocatiom th n i n potassiu f no reductio a , quality e win d an n compositio e grap n i s change d Marke . 1999) these treatments, content c , restrictinphenoli l g tota potassiu , density m d tartratan y e formatiointensit r n colou an y d a particularl reduction in pH buffering capacity in the berries and must and cultivar character were also induced by additional leaf thin- (Ruffner, 1982; Hand, 1987a, 1987b; Gutierrez-Granda & ning of a slanting trellised Cabernet Sauvignon vineyard (Hunter Morrison. 1992) , etal, 1995). n a h wit d decrease y apparentl e profil a arom d measure e Th The relative maintenance of the typical aroma at a rather late berry d include t tha t managemen y Canop . 4) e (Tabl g ripenin n i e increas ripening stage after proper canopy management (and resultant bet- leaf thinning increased the monoterpene content (fruity/tropical ter canopy light microclimate) during the pre-veraison period is aroma)- of thcom eP berribM y e (Tablth f o en 4). Althougstimulatio a ho t generall d relate y e lob wy ibMma d P an val e - noticeabl al.,et n ng/1988)]2 = L (Alie e e th , valu d [threshol d foun e wer s ue pound concentration already in the immature, green berry. concentration of this compound was apparently also stimulated Hashizume & Samuta (1999) found that light exposure increased by these treatments. The total measured aroma profile therefore both 2-methoxy-3-isopropyl- and 2-methoxy-3-isobutylpyrazine seemed to be elevated. Thd e ha grassy/greeveraison) l t i t unti tha p t (u ,bu s n pepper-likgrape e eimmatur aromn i s a in concentration grapes and wine is normally maintained at higher levels when a reducing effect on the levels of these compounds in ripening y (Lace s condition r coole o t d and/od rsubjecte shade e ar s canopie - dur t managemen y canop h wit d foun t effec g stimulatin e Th . grapes et al, f 1991lea n ;i Aliee n &increas Laceye th o t , d 1993;relate Maraie b y s ma et d al., perio 1999)n . In conpre-veraiso -e th g in monoterpenef o n scontributio a arom l tropica d an y fruit e th , trast e carbohydrat f photosynthetio s , availabilitlevel r cactivity highe f yo

TABLE 1 . blanc/11n ripening e 0 grap Sauvigno Richte f g o e rdurin microclimat d an e appearanc y canop n o t effec t managemen y Canop

e appearanc y Canop Microclimate t treatmen t managemen y Canop Gaps Density Bunch Light Temp Rel Air Bunch Berry (leaf layer exposure intensity Hum flow Temp sap temp number) ((imoI/rnVs) (m/h) Suckering, shoot positioning, topping 20 4 10 30.9b* 30.8a 31. la 18a 30.3a 30.5a Suckering, shoot positioning, topping, leaf thinning at berry set 20 4 20 52.8ab 30.8a 31.0a 20a 30.5a 31.0a , topping , positioning t shoo , Suckering leaf thinning at berry set & pea size** 30 4 20 59.1a 30.2a 30.8a 21a 29.7a 30.8a

. parameter h eac r fo ) <0.05 (P y significantl r diffe t no o d r lette e sam e th y b d *Valuesfollowe **Suckering entails removal of shoots not located on spurs. Shoot positioning entails vertical positioning of shoots in line with corresponding spurs. Leaf thinning entails random removal of approx. 33% leaves at berry set in the bunch zone and at pea size in the lower half of canopy.

TABLE 2 blanc/11n . 0Richter Sauvigno f o n compositio t mus d an e grap n o t effec t managemen y canop d an l leve s Ripenes

s solid e Solubl Titratable acidity Free-amino- FAN: t treatmen t Ripenesmanagemen s y Canop pH level (°B) (°B) (g/L) nitrogen (mg/L) °B ratio

19 Suckering, shoot positioning, topping 19.2b* 11. 9a 3.01a 977.5abc 51.0ab , topping , positioning t shoo , Suckering leaf thinning at berry set 19.3b 12.1a 2.97ab 973.0abc 50.7ab , topping , positioning t shoo , Suckering leaf thinning at berry set & pea size** 18.9b 12.3a 2.96b 1070.0a 55.8a

21 Suckering, shoot positioning, topping 21.3a 9.7b 3.00ab 895.0c 42.2d Suckering, shoot positioning, topping, leaf thinning at berry set 20.7a 9.8b 2.96b 894.6c 43.4cd Suckering, shoot positioning, topping, e siz a pe & t se y berr t a g thinnin f lea 21.3a 10.2ab 2.97ab 1015.0ab 47.8bc

S. Afr. J. Enol. Vitic., Vol. 25, No. 1,2004 16 Sauvignon blanc Grape Composition

TABLES blanc/11n 0Sauvigno Richterf o n . compositio e grap n o t effec t managemen y canop d an l leve s Ripenes

) (mg/d mass y aci gdr c Organi Ripeness Glucose: Glucose + Fructose : acid c Tartari • t treatmen t level managemen y Canop Fructose (mg/g dry mass) Citric Tartaric o Malirati d caci c Mali (°B) ratio acid acid acid

g 19 toppin , Suckeringpositioning t shoo , 733.02b* 1.04ab 2.18ab 32.65a 20.69a 1.65d , topping , Suckeringpositioning t shoo , t se y berr t a g thinnin f lea 734.43b 1.04ab 1.99bc 33.33a 19.54a 1.76cd , topping, positioning t shoo , Suckering leaf thinning at berry set & pea size** 768.25a l.OSa 2.25a 31.66ab 14.15b 2.3 lab

21 Suckering, shoot positioning, topping 717.85bc 1.02b 1.94bc 29.98ab 14.21b 2.24ab , topping , positioning t shoo , Suckering t se y berr t a g thinnin f lea 711.48bc l.Olb 1.92c 28.95ab 13.97b 2.12bc Suckering, shoot positioning, topping, e siz a pe & t se y berr t a g thinnin f lea 735.03b l.Olb 1.94bc 28.73ab 11.48b 2.66a

. parameter h eac r fo ) <0.05 (P y significantl r diffe t no o d r lette e sam e th y b d *Valuesfollowe **Suckering entails removal of shoots not located on spurs. Shoot positioning entails vertical positioning of shoots in line with corresponding spurs. Leaf thinning entails . canopy f o f hal r lowe e th n i e siz a pe t a d an e zon h bunc e th n i t se y berr t a s leave % 33 . approx f o l remova m rando

TABLE 4 Ripeness level and canopy management effect on grape composition of Sauvignon blanc/110 Richter.

Ripeness level (°B) Canopy management treatment monoterpenl Tota cone.e ) e(relativ 2-Methoxy-3-isobutylpyrazine (ng/1)

19 Suckering, shoot positioning, topping 15.7 Ibc* 2.43a , topping , positioning t shoo , Suckering leaf thinning at berry set 19.08a 3.01a Suckering, shoot positioning, topping, leaf thinning at berry set & pea size** 19.00a 2.79a

21 Suckering, shoot positioning, topping 14.40c 2.40a , topping , positioning t shoo , Suckering leaf thinning at berry set 18.39ab 2.56a Suckering, shoot positioning, topping, e siz a pe & t se y berr t a g thinnin f lea 18.78a 3.14a

*Values followed by the same letter do not differ significantly (P < 0.05) for each parameter. g thinnin f Lea . spurs g correspondin h wit e lin n i s shoot f o g positionin l vertica s entail g positionin t Shoo . spurs n o d locate t no s shoot f o l **Suckerinremova d gcomprise entails random removal of approx. 33% leaves at berry set in the bunch zone and at pea size in the lower half of canopy. trans-furanoif o m su e th f co linaloo s , cis-furanoioxide lconsist n c linaloo , linalooloxide l concentratio , e cc-terpineolmonoterpen , l trans-pyranoiTota c linaloo, oxide l cis-pyranoic linalool oxide, citronellol, nerol, and diendiol-1.

and a microclimate conducive to higher berry metabolic activity as bolic, morphological, physical and source: sink ratio changes in both well as - transpiratiopre e th g n ratedurin t , affecting managemen sin y k activitcanop y yb and d strengthcreate s . Sincberrie d ean s leave ibMP is a nitrogen-containing compound, the increase in leaf nitrate veraison period (Hunter & Visser, 1988a, 1988b; Candolfi- s thi g durin t managemen y canop h wit y activit reductas e enzym e ; 2000 , Hunter ; al,et 1995 r Hunte ; 1990 , Koblet & s Vasconcelo period as found by Hunter & Ruffner (1997), and which is also evi- Hunter & Ruffner, 2001) stimulated formation of the compound dent from the higher FAN content of the must in this study, may also responsible for the typical green pepper aroma of S. blanc and that have contributet amoun de toth an n increasetha r greate d s formatiowa d nperio os f thithi sg compounddurin d . Aparforme t t amoun e th e increas n a f o e becaus n concentratio n i n reductio s obviou e th m fro s thi f I . sunlight/temperaturperiod y b g d ripenin e degrade th g edurin d sunlight-expose r bette a r fo d restricte s i h (whic e volum y berr n i - pre-veraisof o s manage y ncanop implication e th , realised d indee s i - concen P ibM e th , ripening g durin ) 1990b , Visser & r Hunte - y berr ment for grape composition under cooler conditions than the area tration in the ripe grape mat y thereforexperimen e eth represenh whic n i t ) the WinkleIV s resula n d t roRegio f a classifie bal y - (generall ance betwees n thvigorou e biochemicapromot d lwoul t formatiotha s n of condition th r e compoununde s a l wel d s a pre e - don s wa veraison and its photo/temperature degradation post-veraison. It is growth during the active growth phase would be more pronounced. thus quite possible that the well-exposed canopy and resultant meta- Preferentially, the ripening period should be entered with a homo-

4 200 , 1 . No , 25 . Vol , Enol. J . .Vitic. Afr . S Sauvignon blanc Grape Composition 17 d an e microclimat y canop d an r vigou f o s term n i d vineyar s geneou Candolfi-Vasconcelos, M.C. & Koblet, W., 1990. Yield, fruit quality, bud fertility with grapes that are at a similar level of development and having and starch reserves of the wood as a function of leaf removal in Vitis vinifera - evidence of compensation and stress recovering. Vitis 29, 199-221. compound/phenoliy cprecursor/secondar d compoun y secondar h hig Carbonneau, A. & Deloire, A., 2001. Plant organization based on source-sink rela- compound/flavous response r r compounmolecula d an l d levels, biochemica hig, h acid leveldevelopmental n so ans d a lofinding ww pNe H : tionships e th n r anthocyanii fo n s nformatio precursor f o s level r highe d (an & y . Roubelakis-AngelakiBiolog K.A r : In . Molecula . (ed.) s environment o t case of red grapes). It seems imperative to maintain a well-exposed Biotechnology of the Grapevine, pp. 263 - 280. n obtai o t . [i.e s period n post-veraiso d an - pre e th h bot g durin y canop f o y qualit d an n compositio n o e temperatur f o e Influenc . , E.G.1987 , Coombe maximum photosynthetic activity of all leaves pre-veraiso. n35 - an 3 2 dHort a , toAct 206 . . grapes focus on maximum outpu. 158 - t9 o14 f , younge239 . rHort a leaveAct . s (isink na ths a ey apicaberr e l halgrap e f Th o , f. E.G.1989 , Coombe the canopy and on lateral shoots) and on stimulating older leavec s mali d an Gutierrez-Grandan Morrisondistributio & e . M.-J ,Solut ,. J.C.1992 , (especially in the lower half of the canopy) post-veraison] (Hunter, enzyme activity in developing grape berries. Am. J. Enol. Vitic. 43, 323 - 328. 2000; Hunter & Ruffner, 2001). It is equally important that bunch- Hashizume, K. & Samuta, T, 1999. Grape maturity and light exposure affect d an - pre h bot g durin e exposur t sunligh d filtere o t d subjecte e ar s e berry methoxypyrazine concentration. Am. J. Enol. Vitic. 50, 194 - 198. d an y activit m maximu n obtai o t r orde n i s period n post-veraiso Hunter, J.J., 1999. Present status and prospects of winegrape viticulture in South Africa - focus on canopy-related aspects/practices and relationships with grape - com e th t tha e assum o t e reasonabl s seem t I . sinks e thes f o h strengt and wine quality. In: Proc. llth Meeting Study Group for Vine Training Systems, positional changes brought about by canopy. managemen85 - 0 , Italy7 . pp , Sicily , t in thiMarsala , s 1999 e Jun study would be maintained even when harvesting at a higher Hunter, J.J., 2000. Implications of seasonal canopy management and growth com- e thos m fro r diffe s condition c climati e th n whe r o l leve s ripenes pensation in grapevine. S. Afr. J. Enol. Vitic. 21, 81 - 91. . done s wa y stud s thi h whic r unde e grap e improv o t s strategie n cultivatio m Short-ter . 2001 , E. , Archer & . JJ , Hunter quality. Proc. VHIth Viticulture and Enology Latin-American Congress (on cd), CONCLUSIONS 12-16 November 2001, Montevideo, Uruguay. n pre-veraiso e th g durin t managemen y canop t tha t eviden s i t I Hunter, JJ. & Archer, E., 2002. Paper actual de la gestio del fullatge i perspectives growth phase of the vine in all probability not only increased the futures (Status of grapevine canopy management and future prospects). ACE availability of carbohydrate for accumulation in the bunches, but Rivista d'Enologia 19, 5 - 11. h suc o t s bunche e th d aroun t micro-environmen e th d change o als - physiolog l optima r fo s requirement Bonnardotc & . JJ , Climati . , V.Hunter 2002 , an extent that metabolic m activity Symposiu an l d transpiratioInternationa h 4t . nviticulturan i Proc or . f thfacto e A lzoning berr: y processes l ica . 565 - , France3 55 . pp , Avignon , 2002 e Jun 0 2 - 7 1 , Zoning l Viticultura n o were favoured, thereby increasing sink attraction for precursors reduce -nitrat n i s change l seasona d an l Diurna . 1997 , H.P. , Ruffner & . JJ , Hunter d an s compound y respirator y primar f o n formatio l eventua d an . management y canop f o t Effec : grapevines f o t conten n nitroge d an y taseactivit t greates e th r fo e responsibl e thos s a h suc s compound y secondar Vitis 36, 1 - 6. . harvest t a c blan n Sauvigno f o r flavou d an e palat l fina e th f o t par Hunter, JJ. & Ruffner, H.P., 2001. Assimilate transport in grapevines - effect of l norma e th n i n reductio a o t d lea y ma h whic s practice n Cultivatio . 126 - 8 11 , 7 h Researc e Win d an e Grap . J . Aust . disruption m phloe physiologica- defo l l performancPartia . 1995 , D.J. e, of Roux the eL vine& . C.G an, d the Volschenk accumulatio , H.P. , nRuffner , ofJ.J. , Hunter d avoide e b d shoul y berr e grap e th n i s component d stress-relate t Sauvignon/9, growth Cabeme t . cv roo 9 n Richtero t vinifera Effec : Vitis f o n liatio , 46 . Vitic . Enol . J . Am . quality e win d an , composition e grap , efficiency y canop during both pre- and post-veraison periods. 306-314. t exten e larg a o t l wil s practice m long-ter f o n selectio s Judiciou Hunter, JJ. & Visser, J.H., 1988a. Distribution of 14C-Photosynthetate in the shoot limit the necessity of short-termd an n positio , f seasonalea f o t l effec canop e Th . I y . management . Cabernecv . L Sauvignon t vinifera . Vitis f o However, the data are evidence that under circumstances where developmental stage of the vine. S. Afr. J. Enol. Vitic. 9, 3 - 9. o t e contribut y greatl l wil t managemen y canop l seasona , required 14f C-Photosynthetato n t shoo Distributio e . th n ei 1988b , J.H. , Visser & . JJ , Hunter . defoliation l partia f o t effec e . UTh . Sauvignon t Caberne . cv . L vinifera Vitis f o the exploitation of the full potential of a particular vineyard, also S. Afr. J. Enol. Vitic. 9, 10 - 15. in the case of S. blanc. Evidently, the timing of seasonal canopy n positio f lea , defoliation l partia f o t effec e Th . 1988c , J.H. , Visser & . JJ , Hunter t utmos e th f o e ar d applie s i t i h whic n i y wa e th d an t managemen vinifera Vitis f o y activit c photosyntheti e th n o e vin e th f o e stag l developmenta d an a w allo d woul t tha e structur y canop a e creat o t e importanc L. cv. Cabernet Sauvignon. S. Afr. J. Enol. 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