Impact of Shoot and Cluster Thinning on Yield, Fruit Composition, and Wine Quality of Corot noir

Transcription

1 Impct of Shoot nd Cluster Thinning on Yield, Fruit Composition, nd Wine Qulity of Corot noir Qun Sun, 1 Gvin L. Scks, 2 Steven D. Lerch, 3 nd Justine E. Vnden Heuvel 4,5 * Abstrct: Cluster thinning (CL), shoot thinning (ST), nd combintion of the two prctices (ST+CL) were pplied to vigorous Corot noir (hybrid sp.) winegrpes grown t commercil vineyrd in the Finger Lkes region of New York Stte. Yield ws reduced by CL (by up to 4.8 kg/vine) but not ST in, nd by ST (by up to 2.0 kg/vine) nd not CL in ; however, high pruning weights (up to 4.5 kg/vine in ) nd low crop-lod rtios (rnging from 2.3 to 7.1) indicted tht vines in the study were undercropped regrdless of tretment. CL incresed soluble solids by up to 2.5 Brix in nd by up to 0.8 Brix in the ST+CL tretment in, while ST incresed soluble solids in by 0.8 Brix. The tretments hd vrible impcts on wine nthocynin, berry skin tnnin, berry seed tnnin, nd wine tnnin depending on yer. Wine tnnin (42 to 64 mg/l) nd tnnin extrctbility (5 to 6%) were both very low compred to vlues typiclly observed in red wines produced from V. vinifer. Using two-lterntive forced choice test, pnelists reported ST+CL wines were fruitier thn the control nd ST wines nd tht ST wines were less fruity thn the control in both yers. An economic nlysis indicted tht in order for growers/wineries to mintin their economic welfre, bottle prices would hve to increse by $0.02 to $0.41 depending on the prctice nd yer to compenste for dditionl lbor costs nd lost yield in implementing these crop-lod mngement prctices. Key words: crop-lod mngement, economic sustinbility, cost of production Corot noir is complex interspecific red hybrid winegrpe relesed by Cornell University in It ripens mid- to lte seson, is pproprite for either blending or the production of vrietl wines, nd is modertely winter hrdy (LT50 = -23 C) with moderte resistnce to fungl diseses (Reisch et l. 2006). Observtions mde t Genev, NY, from 1996 to 2005 indicted tht the vine size of Corot noir ws smller thn GR7 (verge pruning weight of 1.4 kg/vine compred to 2.1 for GR7), nd observtions mde during roughly the sme period t three loctions in Indin lso suggest smll vine size (verge pruning weight of 0.6 kg/vine from 2000 to 2005 compred to 1.0 kg/vine for Mrechl Foch t Vincennes, IN) (Reisch et l. 2006). However, necdotl observtions by commercil growers in the Finger Lkes region of New York hve chrcterized Corot noir s perhps the most vigorous French-Americn hybrid grown in the region, exhibiting high fruit yield, vigorous cnopy growth, nd low cluster light exposure. 1 Grdute Student, 2 Assistnt Professor, Deprtment of Food Science, nd 3 Reserch Support Specilist, 4 Assistnt Professor, Deprtment of Horticulture, NYSAES, Cornell University, Genev, NY 14456; nd 5 Deprtment of Horticulture, Cornell University, Ithc, NY *Corresponding uthor (emil: jev32@cornell.edu) Acknowledgments: The project ws funded by the New York Frm Vibility Institute nd the New York Wine nd Grpe Foundtion (Totl Qulity Focus nd Sustinbility progrm). The uthors thnk Swedish Hill Winery for hosting the experiment, Lunn Preston-Wilsey nd Pmel Res for their technicl ssistnce, John Brnrd for dvice on sttisticl nlyses, Tim Mrtinson nd Bill Wilsey for field ssistnce, nd Trent Preszler for contributing expertise to the economic nlysis. Mnuscript submitted Mr 2011, revised Jun 2011, Sept 2011, ccepted Sept 2011 Copyright 2012 by the Americn Society for Enology nd Viticulture. All rights reserved. doi: /jev Both shoot thinning (ST) nd cluster thinning (CL) re recommended viticulturl prctices for mny French-Americn hybrids becuse of their propensity to overcrop (Choon nd Nonnecke 1982). ST hs been shown to improve fruit qulity of severl French-Americn hybrids such s Seyvl blnc (Reynolds et l. 1986), Aurore, Chncellor nd Villrd noir (Morris et l. 2004), nd Mrechl Foch (Sun et l. 2011). CL is commonly used s corrective viticulturl mesure to llow the remining fruit to rech higher level of mturity by improving the lef re to fruit rtio nd hs been demonstrted to improve vrious qulity metrics in Vidl blnc (Wolpert et l. 1983, Howell et l. 1987), Chmbourcin (Prjitn et l. 2007), nd De Chunc (Fisher et l. 1977, Looney 1981). While these studies indicte tht cnopy mngement prctices cn often result in improved fruit qulity, in commercil vineyrd opertion the dditionl costs ssocited with implementing CL nd ST would need to be crefully considered together with the economic benefits of potentil enhncements to fruit qulity (Preszler et l. 2010). Corot noir is reltively recent relese, so there is little informtion vilble on best mngement prctices for this cultivr. The objective of this study ws to investigte the impct of ST nd CL tretments on yield components, fruit composition, nd wine qulity of Corot noir. Mterils nd Methods Vineyrd site nd experimentl design. Five-yer-old own-rooted Corot noir vines locted t commercil winery on the west side of Cyug Lke in Romulus, NY, were subjected to cnopy nd crop-lod mngement tretments in nd. Soil in the block ws Drien-Dnley Czenovi silt lom (USDA-NRCS soil mps). Vines were spced t 2.4 x 2.7 m (vine x row) in north-south oriented rows nd trined to high-wire cordon system with three vines per pnel. 49

2 50 Sun et l. Becuse the northern end of the vineyrd ws lower in vigor thn the southern end, mulch ws pplied in to the two replictions of the experiment locted in the northern end of the plnting. Drip irrigtion ws instlled throughout the vineyrd. Stndrd pest control prctices for the region were used. The experimentl design ws 2 x 2 fctoril with ST nd CL; tretments consisted of two ST tretments (no ST nd ST) combined with two CL tretments (no CL nd CL) in rndomized complete block design with four replictions. Ech experimentl unit consisted of 13 contiguous pnels of vines, with two pnels in ech plot rndomly selected t the beginning of the experiment for dt collection. For the ST tretment in, 15 primry shoots were retined per meter nd ll secondry, tertiry, nd noncount shoots were removed (Mullins et l. 1992, Pool et l. 1978). In, ~30% of primry shoots were dmged by My frost prior to ppliction of the ST tretment, resulting in some secondry shoots being mintined long with primry shoots t density of 15 shoots per meter. ST ws conducted when shoots reched pproximtely 5 to 15 cm in length in My. No ST ws pplied in the control plots. For the CL tretment, the distl cluster ws removed from ech shoot tht hd more thn two clusters. CL ws conducted when berries reched pproximtely pe-size (pproximte Eichhorn Lorenz stge 31), nd no CL ws pplied in the control plots. Yield components. Vines were individully hrvested by hnd on 21 Oct nd 16 Oct immeditely before commercil hrvest. Yield per vine ws quntified using hnging scle (Slter Weigh-Tronix, Firmont, MN), nd cluster number per vine ws counted. Cluster weights were clculted by dividing yield by cluster number on per vine bsis. A rndom smple of 20 clusters per dt pnel ws collected t hrvest nd stored t -40 C until nlysis. Subsmples of 100 berries were weighed to determine men berry weight. Berry number per cluster ws clculted by dividing cluster weight by berry weight. In Jnury 2010, vines were pruned ccording to grower specifictions nd pruning weights were collected on per vine bsis in ech dt pnel. Crop lod for ws clculted by dividing yield by pruning weight on per vine bsis. In Jnury, the grower pruned ll vines in the plnting prior to dt collection. As result, pruning weights were estimted immeditely following commercil pruning on per pnel bsis by rking nd weighing the vine prunings which were lying on the vineyrd floor between the posts defining the dt collection pnels. Crop lod for ws clculted by dividing yield by pruning weight on per pnel bsis. Cnopy chrcteriztion. Enhnced point qudrt nlysis (EPQA) (Meyers nd Vnden Heuvel ) ws used to chrcterize cnopy light environment t pproximtely verison in both yers of the study. A shrpened thin metl rod ws inserted into the cnopy t 10 cm intervls nd sequentil contcts of leves, clusters, nd cnopy gps from one side to the other were recorded. Photon flux mesurement ws performed ccording to previously described method (Meyers nd Vnden Heuvel ) using Decgon ceptometer (Decgon, Pullmn, WA). Cnopy prmeters were nlyzed by EPQA nd CEM Tools (version 1.6) (vilble free of chrge from J. Meyers, jmm533@cornell.edu). Occlusion lyer number (OLN; number of shde producing contcts per insertion), cluster exposure lyer (CEL; number of shding lyers between cluster nd nerest cnopy boundry), cluster exposure flux vilbility (CEFA; percentge of bovecnopy photon flux tht reches clusters), nd lef exposure flux vilbility (LEFA; percentge of bove-cnopy photon flux tht reches leves) were clculted. Berry nd wine composition. A 100 berry smple ws collected rndomly in duplicte from ech smple tht ws frozen s described bove. The frozen berries were thwed t room temperture before nlysis. The berries were juiced by blender nd the slurry ws pressed through cheese cloth. Brix ws mesured using n Abbé temperture-compensted refrctometer (ATAGO, Bellevue, WA). Berry nd wine ph were mesured using n Orion 3-Str ph meter (Thermo Fisher Scientific, Wlthm, MA), nd titrtble cidity (TA) ws determined on 10 ml smple by utotitrtion (Digitl Buret, BrndTech Scientific, Essex, CT) using 0.1 M NOH to n endpoint of ph 8.2. Wine lcohol content ws mesured by ebulliometer (DuJrdin-Slleron, Arcueil, Frnce). Wine lctte, cette, glucose, nd fructose were quntified by Fourier trnsform IR (WineScn FT120 Bsic, FOSS, Eden Pririe, MN) to confirm tht fermenttions went to dryness nd spoilge did not occur (dt not shown). Wine free SO 2 ws mesured by the Ripper method (dt not shown). Berry nd wine nthocynins nd tnnins were determined by the Adms Hrbertson ssy (Hrbertson et l. 2003). Tnnin extrctbility ws clculted by the following eqution: The rtio of the wine volume (L) to the fruit mss represents yield (kg). A men yield vlue of 0.65 ws used for ll tretments. Winemking. Wines were mde in duplicte fter combining ll four field replictes for ech tretment nd then subdividing the fruit into duplicte lots. Fruit ws destemmed, crushed, nd treted with 50 mg L -1 sulfur dioxide dded s potssium metbisulfite. Dimmonium hydrogen phosphte (DAP) (Presque Isle Wine Cellrs, PA) ws dded t rte of 1 g kg -1, Fermid K (Lllemnd, Rexdle, ON, Cnd) t 0.1 g L -1, nd Goferm (Lllemnd) t 0.15 g L -1. Skin fermenttion ws performed in temperture-controlled 114 L stinlesssteel fermentors. Cp mngement ws performed twice per dy by mnul punch-downs. The must ws brought to 20 C nd inoculted with ICV-GRE (Lllemnd) to 0.27 g L -1. The temperture profile of the fermenttions ws computer controlled. During the first three dys of fermenttion, the must ws wrmed slowly from 20 C to mximum between 30 nd 35 C. For the reminder of the lcoholic fermenttion, the temperture ws kept between 20 nd 30 C. Fermenttions were stopped when residul sugr ws <0.5% by Clinitest tblets

3 Impct of Shoot nd Cluster Thinning on Corot noir 51 (Byer, Etobicoke, ON, Cnd). At the end of fermenttion, wines were pressed, rcked into glss crboys, nd inoculted with Alph (Lllemnd) to strt mlolctic fermenttion (MLF). Upon completion of MLF, potssium metbisulfite ws dded to mintin 40 mg L -1 free sulfur dioxide. Wines were cold stbilized t 2 C. Titrtble cidity ws djusted to 6.5 g L -1 by ddition of trtric cid or potssium crbonte fter cold stbiliztion. The wines were screened for fults by n expert pnel prior to bottling. Bottling nd screwcpping were performed mnully. Sensory test. Wines from nd were evluted fter bottle ging nd compred in November 2010 for ll four tretments by two-lterntive-forced choice (2-AFC) test (Lwless nd Heymnn 2010). Sixteen pnelists with wine evlution experience were recruited for the test. A pir of coded smples for comprison ws presented to pnelists. The pnelists were sked to select the smple with the stronger fruitiness. Wines from ech tretment were compred to one nother. Ech comprison ws duplicted. One wine smple ws rndomly selected for sensory evlution from duplicte wines. Presensory testing ws performed to ensure the replictes did not differ. Economic nlysis. A simple economic nlysis ws performed to determine the dditionl price per tonne nd cost per 750 ml bottle of wine producer would need to receive in order for them to mintin the sme economic welfre (i.e., revenue/h or revenue/cse) if the ST or CL prctices were dopted compred to if they were not. Additionl production cost per hectre for ech tretment ws determined ccording to White (), nd then dditionl production cost/tonne ws clculted by dividing the dditionl production cost/h by the yield (tonne/h). Expected revenue/h ws clculted by multiplying yield (tonne/h) by the verge industry price for Corot noir (Wlter-Peterson, ). The grower preferred price/tonne to mintin economic welfre ws clculted by dividing the expected revenue/h for the control tretment ($13,279 in, $4,844 in ) by the yield (tonne/h) nd then dding the dditionl production cost/tonne. Additionl cost per 750 ml bottle of wine ws determined by subtrcting the verge price per tonne from the grower preferred price/tonne for ech tretment, nd then dividing by (the number of 750 ml bottles tht cn be produced from one metric tonne of grpes). Sttisticl nlysis. Mixed model ANOVAs nd LSDs were generted using JMP (version 8.0; SAS Institute, Cry, NC), with type I error rte ( ) set t 0.05 for ll sttisticl tests. Sttisticl nlysis of the 2-AFC test ws performed by two-tiled chi-squred test (JMP 8.0). Results nd Discussion Yield components nd vine growth. In, CL decresed yield through decrese in cluster number per vine compred to the control (Tble 1). However, individul cluster weight ws incresed by both ST nd CL. Croplod rtio ws decresed by both ST nd CL. The ST by CL interction ws significnt nd hd n dditive effect for cluster number per vine nd berry weight. In, CL resulted in fewer clusters per vine compred to the control, but the incresed verge cluster weight resulted in CL hving no impct on yield per vine, similr to results reported for Seyvl blnc (Reynolds et l. 1986). ST significntly reduced yield per vine in through decrese in cluster number (Tble 1). Crop-lod rtio ws reduced by ST, while CL surprisingly hd no impct on crop lod t hrvest. Tretment Tble 1 Impct of shoot thinning nd cluster thinning on yield components nd vegettive growth of Corot noir. Yield/ vine (kg) Clusters/ vine Cluster wt (kg) Berries/ cluster Berry wt (g) Pruning wt (kg) Crop lod (kg yield/kg pruning wt) Control ST + CL CL ST ST < < CL < < < ST x CL LSD Control ST + CL CL ST ST < < CL < < ST x CL LSD Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters).

4 52 Sun et l. Individul cluster weight ws incresed 20 g by ST nd CL seprtely (Tble 1). The ST*CL interction ws significnt with n dditive effect for yield per vine, clusters per vine, nd berry weight in. Pruning weights nd yields in both yers, but prticulrly in, confirmed the grower reports of high vigor in Corot noir. Pruning weights reported here for (rnging from 2.6 to 4.5 kg/vine, or 1.1 to 1.8 kg/m cnopy) were considerbly higher thn those reported for other hybrids on nondivided systems in other cool-climte growing regions (Dmi et l. 2006, Reynolds et l. 1995, 2004) s well s in New York (Sun et l. 2011). Concord in New York is generlly reported to hve pruning weights below ~2 kg/vine (0.8 kg/m cnopy) (Btes, Poni et l. 1994), suggesting tht Corot noir, in some instnces, my be higher in vigor thn Concord. However, hybrids in Arknss hve been reported to hve similr vigor to tht reported here for Corot noir (Morris et l. 1984, 2004). Vines in ll tretments of this study hd crop lods tht were below the generlly ccepted rnge for hybrids (Dmi et l. 2006, Reynolds 1989, Reynolds et l. 2004), likely resulting in incresed vegettive growth of vines. ST nd CL seprtely reduced cnopy density s reflected by the reduction in OLN nd similr decrese in CEL in. While there were fewer shde-producing contcts in the cnopy s well s fewer shding lyers between clusters nd the nerest cnopy boundry, the percentge of photon flux tht reched the clusters (CEFA) nd leves (LEFA) did not differ mong tretments, suggesting tht if chnges in cnopy density impcted fruit growth nd composition, it ws not through chnges in cluster or lef light environment. ST nd CL hd no impct on OLN, CEL, CEFA, or LEFA in (Tble 2). CEL nd OLN were generlly higher nd CEFA nd LEFA were lower in compred to, suggesting more dense cnopy through the fruiting zone despite the fct tht pruning weights in were less thn hlf of those reported for (Tble 1). Differences between yers in yield per vine nd pruning weight were striking, with vines in producing less thn hlf the yield nd pruning weight of. A spring frost in My resulted in loss of ~30% of primry shoots. Our observtions indicted tht secondry shoots were extremely fruitful; however, the verge cluster weight in ws generlly t lest 100 g less thn in, nd berry number per cluster ws lso considerbly lower. Additionlly, yield ws likely reduced in s result of the excessive vigor of the vines in, resulting in poor florl bud initition in tht yer. Fruit nd wine composition. In, soluble solids ws incresed by 2.5 Brix with CL compred to the control (Tble 3), but ws not ffected significntly by ST. However, ph incresed slightly nd TA decresed s result of ST, while CL hd no impct on either prmeter. In, berry ph nd soluble solids were incresed by ST nd CL, lthough the increses were low (<0.8 Brix compred to the control). TA decresed slightly s result of ST (Tble 3), but ws unffected by CL, result tht hs been similrly reported in other hybrid studies investigting CL (Dmi et l. 2006, Morris et l. 1987). Decreses in TA during ripening re due to both K + /H + exchnge nd respirtion of mlic cid (Boulton et l. 1996). Mlic cid respirtion increses t higher berry tempertures, which cn result from greter cluster exposure. However, since the tretments did not lter cluster light environment, greter potssium uptke my be more plusible explntion for the decrese in TA observed with ST. Greter potssium uptke by vines subjected to ST nd/or CL is lso the most likely explntion for the increse in ph observed with both prctices. However, the biologicl relevnce of ph of 3.53 compred to 3.58 is questionble. Berry nthocynin concentrtion, expressed s mlvidin-3- glucoside equivlents, rnged from 990 to 1260 mg/kg berry weight cross tretments nd yers (Tble 4). These concentrtions re comprble to severl of the more intensely pigmented V. vinifer cultivrs such s Cbernet Suvignon (Boulton et l. 1996). The concentrtion of nthocynins in wines rnged from 670 to 900 mg/l, or men of 67% of the concentrtion observed in grpes, with mximum of 86% observed for the ST + CL tretment. Both of these vlues re bout fctor of 2 greter thn typicl nthocynin concentrtions (300 to 500 mg/l) nd typicl extrction efficiency (20 to 50%) for red wines (Boulton et l. 1996). Anthocynin extrction efficiency is known to vry mong cultivrs nd sites (Romero-Cscles et l. 2005), lthough the fctors tht limit nthocynin extrctbility re not well understood. The ph differentil method used here is designed to quntify monomeric nthocynins, nd possible explntion for our observed results is tht the low tnnin concentrtion of the Corot noir wines (described below) resulted in reduced Tble 2 Cnopy chrcteriztion of Corot noir. Cnopy vrible b Tretment OLN CEL CEFA LEFA Control ST + CL CL ST ST CL ST x CL LSD Control ST + CL CL ST ST CL ST x CL LSD Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters). b OLN: occlusion lyer number; CEL: cluster exposure lyer; CEFA: cluster exposure flux vilbility; LEFA: lef exposure flux vilbility.

5 Impct of Shoot nd Cluster Thinning on Corot noir 53 polymeric pigment formtion nd consequently less immedite loss of the nthocynins. Interestingly, we lso observed significntly higher extrction rtio in thn in (75% vs. 59%, p < 0.05), lthough the resons for this difference re not obvious, s the sme fermenttion procedures were followed in both yers. No significnt difference in berry skin weight (dt not shown) or berry weight (Tble 1) ws observed, so greter dsorption to solids seems unlikely. Berry skin tnnin nd seed tnnin concentrtions rnged from 0.2 to 0.3 mg/g berry nd 0.8 to 1.2 mg/g berry, respectively, which re comprble to some V. vinifer cultivrs (Hrbertson et l. 2002). Berry skin tnnin ws not ffected Tble 3 Impct of shoot thinning nd cluster thinning on berry nd wine composition of Corot noir. Musts were chptlized prior to fermenttion to the sme potentil lcohol. Berry Wine Tretment ph Brix TA (g/l) ph Alcohol (% v/v) TA (g/l) Control ST + C CL ST ST CL ST x CL LSD Control ST + C CL ST ST CL ST x CL LSD Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters). Tretment Tble 4 Impct of shoot thinning nd cluster thinning on berry nd wine nthocynin nd tnnin of Corot noir. Berry nthocynin (mg M-3-G/kg fresh berry wt) b Wine nthocynin (mg M-3-G /L) b Berry skin tnnin (mg/berry ctechin) Berry seed tnnin (mg/berry ctechin) Wine tnnin (mg/l ctechin) % Tnnin extrction Control ST + CL CL ST ST CL ST x CL LSD Control ST + CL CL ST ST CL ST x CL LSD Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters). b Mlvidin-3-glucose equivlents.

6 54 Sun et l. by ST or CL in, lthough berry seed tnnin ws reduced slightly by ST (Tble 4). Berry skin tnnin ws decresed by CL in, but ws unffected by ST; seed tnnin ws not ffected by either prctice. Wine tnnin ws decresed by both ST nd CL in, but the concentrtions of wine tnnin (42 to 64 mg/l) were n order of mgnitude below typicl concentrtions observed in red wines mde from V. vinifer cultivrs (Hrbertson et l. ). The tnnin extrctbility ws very low (6%) (Tble 4) compred to the wine mde from V. vinifer species (4.9 to 61%) (Hrbertson et l. 2002, Bindon et l. 2010, Adms nd Scholz ). This finding is consistent with previous study tht reported tnnin extrctbility of 2 to 4% for the hybrid cultivr Mrechl Foch (Sun et l. 2011). The low tnnin extrctbility my be prtly due to low skin tnnin concentrtions in Corot noir (0.2 to 0.3 mg/berry) s compred to V. vinifer, s skin tnnin ppers to be more rpidly nd effectively extrcted during fermenttion (Smpio et l. 2007). Additionlly, insoluble grpe cell wll mteril cn bind to tnnins nd limit its extrctbility (Bindon et l. 2010). Potentilly, the cell wll mteril of hybrid winegrpes my bind tnnins more strongly thn in V. vinifer, lthough tht would need to be investigted. ST nd/or CL hs been reported to improve fruit composition (prticulrly soluble solids) in the more vigorous hybrid cultivrs, t lest in some yers (Reynolds et l. 1986, Wolpert et l. 1983, Prjitn et l. 2007, Dmi et l. 2006). The results of this study were vrible with respect to yield components nd vine size, but CL incresed soluble solids in both yers while ST reduced TA (Tble 3). CL lso reduced wine tnnin in both yers s indicted by s compred to the control (Tble 4), which could be considered detrimentl impct. Wine sensory nlysis. Pnelists were ble to detect differences in fruitiness between ST+CL nd the control from both vintges (Tble 5), with the ST+CL wines considered more fruity thn the control. An dditionl difference in fruitiness ws observed between ST+CL nd ST wines in both yers nd between the CL nd control in (Tble 5). Surprisingly, the ST tretment lone ws perceived s less fruity thn the control in both nd. The results from the sensory nlysis were surprisingly consistent cross both yers, s the growing sesons differed with respect to ccumulted GDD from 1 My to 31 Oct ( = 1302 GDD bse 10 C, = 1221 GDD; dt sourced from the Genev, NY, wether sttion mintined by Network for Environment nd Wether Applictions, s well s yield nd pruning weight (Tble 1). Precipittion did not vry gretly between yers from 1 My to 31 Oct ( = 519 mm, = 549 mm), lthough precipittion from 1 My to 30 June ws much higher in (220 mm) compred to the sme period in (132 mm). There is no pprent viticulturl explntion s to why the ST+CL (nd CL wines in ) were considered more fruity thn the control, or why the ST wines were rted less fruity thn the control. A chemicl understnding of wht controls fruitiness/herbceousness in Corot noir would fcilitte interprettion of the sensory dt presented here. Tble 5 Sensory results from two-lterntive-forced choice test of Corot noir. The proportion of 1 more fruity thn 2 is 0.5 by chnce, nd s were clculted by chi-squred test (two-til). Tretment Proportion 1 more fruity thn 2 (1-ST+CL/2-Control) (1-CL/2-Control) (1-ST/2-Control) 0.18 <0.001 (1-ST+CL/2-CL) (1-ST/2-CL) (1-ST+CL/2-ST) 0.93 <0.001 (1-ST+CL/2-Control) (1-CL/2-Control) (1-ST/2-Control) (1-ST+CL/2-CL) (1-ST/2-CL) (1-ST+CL/2-ST) 0.88 <0.001 Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters). Cost of implementing prctices. A simple ccounting nlysis of the costs of implementing CL nd ST ws performed in order to depict relistic finncil scenrio for commercil Corot noir growers of the potentil costs nd benefits of dopting these prctices. Vrible production costs of growing winegrpes in the New York Finger Lkes region were estimted bsed on published report of V. vinifer production (White ). The two primry costs ssocited with implementing ST nd/or CL re (1) dditionl vineyrd lbor hours required to complete the thinning in consort with other ongoing field prctices nd (2) potentil opportunity cost if totl yield is decresed s result of either prctice nd thus there re fewer grpes to sell nd/or mke into wine. It is likely tht the cost of lbor estimtes used in our nlysis tht were determined for V. vinifer (White ) re lower thn would be required for hybrids due to the generlly lrger cnopy size of hybrids; therefore, required prices to compenste for lbor costs my be higher thn reported here. If grower hs to spend money to implement cluster nd/or ST, nd then hs fewer grpes to sell t the stndrd industry price, then the grower cn expect to receive lower totl revenue for their crop. Logiclly, if grower expects to mintin the sme level of welfre (totl revenue) following implementtion of ST nd/or CL, the price they chrge for Corot noir grpes would need to be bove mrket price. In nd the verge prices for Corot noir grpes in the Finger Lkes were $570 nd $503 per tonne, respectively (Wlter-Peterson, ). The price per tonne of Corot noir grpes in tht grower would need to chrge in order to mintin constnt welfre would increse from bse mrket price of $570 per tonne for the control up to $865 per tonne for the ST+CL vineyrd (Tble 6). For the sme prmeters in, the price per tonne to mintin constnt grower welfre would need to increse from $503

7 Impct of Shoot nd Cluster Thinning on Corot noir 55 Tretment Additionl production cost/h Tble 6 Production cost nd price nlysis of Corot noir. Additionl production cost/tonne Yield tonnes/h Expected revenue/h b Preferred price/ tonne to mintin welfre c Additionl cost/bottle d Control $0 $ $13,279 $570 $0.00 ST+CL $287 e $ $8,938 $865 $0.41 CL $153 f $ $10,215 $749 $0.25 ST $133 g $ $12,002 $637 $0.09 Control $0 $0 9.6 $4,844 $503 $0.00 ST+CL $287 $ $3,492 $738 $0.33 CL $153 $ $4,844 $518 $0.02 ST $133 $ $4,055 $616 $0.16 Control: no shoot thinning nd no cluster thinning; ST: shoot thinning (15 primry shoots/m); CL: cluster thinning (distl cluster removed on shoot contining >2 clusters). b Expected revenue commercil grower cn expect to receive for Corot noir clculted by multiplying yield (tonnes) by the reported verge industry price for Corot noir ( = $570/tonne, = $503/tonne). c Price per tonne of Corot noir tht commercil grower would need to chrge to compenste for the two min costs ssocited with implementing thinning prctices: reduced grpe yield nd dditionl production costs. d Additionl cost per bottle produced fter implementing thinning prctices, if the commercil grower retins grpes to mke wine insted of selling them t mrket price. Assumes L wine (or bottles) per tonne of grpes. e Additionl production cost per hectre for ST nd CL in V. vinifer, estimted from White (). f Additionl production cost per hectre for CL in V. vinifer (White ). g Additionl production cost per hectre for ST in V. vinifer (White ). to $738 per tonne. The vribility in these prices reflects the specific prctices implemented (Tble 6). The increse in price per 750 ml bottle required to compenste for the higher fruit costs plus dditionl vineyrd lbor rnged from $0.09 to $0.41 in nd from $0.02 to 0.32 in. It is uncler whether hybrid fruit growers who implement ST nd/ or CL could recpture their costs by chrging substntilly higher mrket prices or whether grpe buyers would be willing to py such premium without compelling enhncements to fruit qulity or flvor. However, the sensory nlysis results in this study indicte consistent increse in fruitiness with CL (lone in or combined with ST in both yers), chrcteristic positively ssocited with consumer preference (Bogrt nd Bisson 2006). Wine consumers my be willing to py more for such wines or my be more likely to purchse the wine gin. Ultimtely, hybrid grpegrower s decision of whether to implement thinning prctices is best determined bsed on rtionl nlysis of the potentil costs nd benefits similr to the one presented here. Conclusion The Corot noir vines used in this study were extremely vigorous, with high pruning weights nd low crop lods. While the impct of ST on yield nd yield components vried in the two yers of this study, ST ws consistent in reducing both croplod nd TA in both yers. CL lso demonstrted vrible impct on yield nd yield components, but improved soluble solids in both yers. Incresing retined node numbers during dormnt pruning my hve more successfully improved fruit composition by reducing overll vine vigor. Surprisingly, the impct of ST nd CL on the wine sensory nlysis ws consistent: in both yers of the study, the pnelists reported tht the ST+CL wine ws perceived s more fruity thn the control nd tht the ST+CL wine ws perceived s more fruity thn the ST only wine. Poor tnnin extrction from Corot noir ws observed, which is consistent with previous work on Mrechl Foch, nd could potentilly be the result of binding between cell wll mteril nd tnnins. If tht occurs, it would compromise the effectiveness of exogenous tnnin dditions to hybrid red wine fermenttions, s is sometimes prcticed commercilly. Further investigtion into the poor tnnin extrction from hybrids is wrrnted. Lstly, implementing CL nd/or ST would require hybrid grpegrower to chrge considerbly higher prices for their grpes to compenste for the lost yields nd dditionl production costs. It is uncertin whether the qulity or flvor enhncements to Corot noir fruit s result of CL nd/or ST would wrrnt such price increses under existing hybrid winegrpe mrket conditions. Literture Cited Adms, D.O., nd R.C. Scholz.. Tnnins the problem of extrction. In Proceedings of the Thirteenth Austrlin Wine Industry Technicl Conference. R. Blir et l. (eds.), pp AWITC, Glen Osmond, South Austrli. Btes, T.. Pruning level ffects growth nd yield of New York Concord on two trining systems. Am. J. Enol. Vitic. 59: Bindon, K.A., P.A. Smith, nd J.A. Kennedy Interction between grpe-derived pronthocynidins nd cell wll mteril. 1. Effect on pronthocynidin composition nd moleculr mss. J. Agric. Food Chem. 58: Bogrt, K., nd L. Bisson Persistence of vegetl chrcters in winegrpes nd wine. Prc. Winery Vineyrd 26: Boulton, R.B., V.L. Singleton, L.F. Bisson, nd R.E. Kunkee Principles nd Prctice of Winemking. Chpmn & Hll, New York. Choon, G.A., nd G.R. Nonnecke Cluster nd shoot thinning s commercil culturl prctice. In Proceedings of the Ohio Grpe-Wine Short Course, pp Ohio Agriculturl Reserch nd Development Center, Wooster.

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