Effect of Irrigation on Vegetative and Reproductive Behavior of Sauvignon blanc in Italy

Effect of Irrigation on Vegetative and Reproductive Behavior of Sauvignon blanc in Italy P. Storchi, F. Giorgessi, P. Valentini F. Bonello and P. Tamborra and L. Tarricone Istituto Sperimentale per l Enologia Istituto Sperimentale per la Viticoltura Asti Conegliano Italy Italy Keywords: environment, stem water potential, grape quality, aroma compounds Abstract Vegetative and reproductive growth and fruit characteristics of Sauvignon blanc were measured at three locations in Italy (, and Italy) with different water regimes, under irrigation and without irrigation. Soil water content, air temperature and precipitation were monitored in 2003. Stem water potential was measured once a week from anthesis to harvest. Cluster number and weight per vine were measured at harvest. Total acidity, ph, soluble solids and aroma contents were determined on the must. There were clear differences among locations and irrigation treatments on must quality. The results indicate the importance of judicious irrigation for preserving Sauvignon blanc grape quality, particularly at locations subjected to soil water deficits combined with high temperature. INTRODUCTION The vegetative cycle and fruit ripening of the grapevines is strongly influenced by the environment and soil water availability (Calò et al., 2002). However, vegetative and reproductive growth can be ameliorated by the use of irrigation which may ultimately affect fruit quality (Bravdo and Naor, 1996; Tandonnet et al., 1999). Once the decision to irrigate has been made the amount of water to apply and when to apply it during the growing season may affect fruit quality. The ability to monitor vine water status such as the measurement of the stem and leaf water potential (Van Leeuwen et al., 2003) could aid in making such decisions. Aroma characteristics are particularly important in wine. The aroma of the Sauvignon blanc is closely associated with the presence of methoxypyrazines (Bayonove et al., 1994) and sulfur compounds, odorless precursors that are transformed into aroma during fermentation that are found in the berries (Darriet, 1993; Dubourdieu and Darriet, 1993). In addition, other compounds such as monoterpenes, norisoprenoids, benzoic compounds and aliphatic alcohols which give the wine other aromas (fruit, flowers, spices, honey, etc.) also contribute to final olfactory perception (Augustin et al., 1982). The object of the present research was to evaluate the productive responses of Sauvignon blanc to different environmental situations and irrigation. This work was also used to establish easily measurable parameters in order to supply wine-growers indications on how to manage these interventions and therefore enhance the quality of the product. MATERIALS AND METHODS The research was conducted during 2003 at three different locations in Italy, from 46 to 39 north latitude, the (Veneto), the (Tuscany) and the (Apulia). At each location, a drip irrigated Sauvignon blanc vineyard was chosen. The vines were trained to a single cordon, leaving from 12 () to 16 () buds per vine and a vine density of 3000 () to 3800 () vines ha -1. The vines were grafted onto SO4 () and 775P ( and ). The textural characteristics of the soil were as reported in Table 1. The vineyards at the and locations had a sandy Proc. VII th IS on Grapevine Ed. L.E. Williams Acta Hort. 689, ISHS 2005 349

soil type while the soil at the location was a loam. Three treatments were imposed at each location using pre-determined values of stem water potential (Ψ stem ) during the period from pre-veraison to the grape harvest at which to initiate an irrigation event: T1) Ψ stem < - 0.8 MPa, T2) Ψ stem - 0.8 MPa, and T3) Ψ stem > - 0.8 MPa. Stem Ψ was measured with a pressure chamber, according to the technique of Choné et al. (2001). Mature leaves were bagged before the measurements. Measurements were taken weekly and when Ψ stem varied from the treatment threshold an irrigation event was initiated the following day. Soil water content was estimated according to the procedure of Giorgessi et al. (2001), adjusted for soil type and expressed as percent available water. At harvest, a 400 berry sample was obtained from each treatment. The samples were collected early in the morning (0700 h). Berries were analyzed for monoterpenes, norisoprenoids, benzoic compounds and aliphatic alcohols using the methodology of Ummarino and Di Stefano (1997). A sample of the must was used to determine soluble solids ( Brix), titratable acidity (TA) and ph. Mean cluster and berry weights were also measured at harvest and pruning weights during winter. Lastly, wines were made of all treatments at the location and evaluated for sensory attributes using descriptive characteristics. Data were analyzed using analysis of variance (ANOVA) and means separated via LSD. RESULTS AND DISCUSSION The year 2003 was warmer and more arid compared to the multi-year mean, particularly at the location (Table 2). This resulted in an earlier grape harvest which occurred on August 14, 25 and 28 at the, and locations, respectively. Stem water potential averaged -0.8 MPa until Day of Year 200 (20 July) and subsequently decreased, the absolute amount depending upon treatment (Fig. 2). The lowest Ψ stem (-1.4 MPa) was measured for the T1 treatment at the Middle and locations. The amount of applied water varied as a function of treatment and location (Table 3). The locations received more applied water as follows: 2 irrigations (the amount was equal for all treatments), pre-anthesis/fruit set and 2 irrigations on July 17 and 27. There was a significant interaction of location and irrigation treatment on Brix, TA, ph, cluster weight, and the Ravaz Index. Location strongly influenced sugar content and the acidity of the must, i.e. warmer environments ( and locations), had higher sugar levels and lower acidity (Fig. 2). The effect of irrigation treatment on Brix was very much dependent upon location. Cluster and pruning weights were mainly influenced by irrigation treatment (Fig. 3). Berry weights at the ern location were significantly greater for the T3 (1.15 g) than for the T2 (0.93 g) and T1 (0.88 g) irrigation treatments. Aliphatic alcohols tended to be higher at the warmer locations ( and ), while the norisoprenoids tended to be higher at the cooler () location (Table 5). The effects of irrigation on the aromatic compounds depended upon the unit of measurement used (µg kg -1 or µg 100 berries -1 ) but in general more applied water decreased their values (Tables 5 and 6). The effect of the irrigation treatments was analyzed in more detail for grapevines at the southern, warmer and more arid environment location. At this location soil water content decreased to 11% for the T1, 20% for the T2 and 29% for the T3 treatment (Table 7), and stem water potentials went from approximately -0.5 (T1) to -0.8 (T2) to -1.4 MPa (T3). Sensory evaluation of wines made from fruit at the southern location demonstrated that the herbaceous aroma (tomato, green beans, pepper) was similar among irrigation treatments (Fig. 4). Sulfur compounds (fig, cat), fruit (banana, apple) and elder aromas were greater for the T2 treatment followed by the T3 and finally T1 treatments. The global evaluation of the wines followed the same order. Wine produced from grapes of the T2 treatment received a much higher score compared to those of the T1 and T3 treatments. 350

CONCLUSIONS Differences among irrigation treatments were due mainly to climatic conditions during fruit ripening. At each location irrigation treatments, established according to stem water potential, had a significant effect. Stem water potential allowed us to estimate vine water status with good precision. Among the applied irrigation regimes, the T2 treatment gave the best performance compared to the T1 and T3 treatments. This allowed for a savings of irrigation water. The T3 treatment did not markedly improve fruit quality at the and locations while in the it had a negative effect. Overall, fruit from the T2 treatment had a better qualitative level, particularly regarding the sugar content, and the complexity of the aromatic compounds was not excessively penalized. For wine produced in the, the T2 treatment received a greater score in respect to the other wines, with a very appreciated aroma. In this wine the fruit aromas were noted mostly, but also there were aromas typical of the wine, derived from the sulphur compound. The herbaceous aromas, instead, bound to the methoxypyrazines, having been quite noted from the panel of the tasters, seemed not to depend, in this case, from the contributions of irrigation. ACKNOWLEDGEMENTS We would like to thank the Bellussi (Treviso, Italy), Rocca di Castagnoli (Siena, Italy) and Di Maggio (Taranto, Italy) farms for their collaboration. Literature Cited Allen, M.S., Lacey, M., Harris, R.L.N. and Brown, W.V. 1991. Contribution of methoxypyrazines to Sauvignon wine aroma. Am. J. Enol. Vitic. 42:109-112. Augustyn, O.P.H., Rapp, A. and Van Wik, C.J. 1982. Some volatile aroma components of Vitis vinifera L. cv Sauvignon blanc. S. Afr. J. Enol. Vitic. 3:53-60. Bayonove, C., Cordonnier, R. and Dubois, P. 1975. Etude d une fraction caractéristique de l arôme de la variété Cabernet-Sauvignon; mise en évidence de la méthoxy-3- isobutylpyrazine. C.R. Acad. Sc. Paris, Ser. D. 281:75-78. Bravdo, B. and Naor, A. 1996. Effect of water regime on productivity and quality of fruit and wine. Acta Hort. 427:15-26. Calò, A., Costacurta, A., Giorgessi, F. and Ubigli, M. 2002. Importance of the soil moisture on the growth-yield balance of vines and on the sensorial quality of wines. Riv. Vit. Enol. Conegliano,1:25-39. Choné, X., Van Leeuwen, C., Dubourdieu, D. and Gaudillere, J.P. 2001. Stem water potential is a sensitive indicator for grapevine vine status. Ann. Bot. 4:477-483. Darriet, Ph. 1993. Recherches sur l arôme et les précurseurs d arôme du Sauvignon Applications technologiques, Doctorat de l Università de Bordeaux II, 187. Dubordieu, D. and Darriet, Ph. 1993. Ricerche sull aroma varietale del Sauvignon. Vignevini 7-8:38-41. Giorgessi, F., Calò, A., Tomasi, D. and Catalano, V. 2001. Bilan hydrique: une méthode proposée pour l évaluation des réserves hydriques dans le zonage viticole. Riv. Vit. Enol. di Conegliano 1:3-15. Lacey, M., Allen, M.S., Harris, R.L.N. and Brown, W.V. 1991. Methoxypyrazines in Sauvignon blanc juice and wine. Amer. J. Enol. Vitic. 42:103-108. Marais, J. 1994. Sauvignon blanc cultivar aroma. S. Afr. J. Enol. Vitic. 15:41-45. Sefton, M.A., Francis, I.L. and Williams, P.J. 1994. Free and bound volatile secondary metabolites of Vitis vinifera grape cv. Sauvignon blanc. J. Food Sci. 59:142-147. Tandonnet, J.P., Ollat, N., Neveux, M. and Renoux, J.L. 1999. Effect of three levels of water supply on the vegetative and reproductive development of Merlot and Cabernet Sauvignon grapevines. Acta Hort. 493:301-307. Trégoat, O., Van Leeuwen, C., Choné, X. and Gaudillere, J.P. 2002. Etude du régime hydrique et de la nutrition azotée de la vigne par des indicateurs physiologiques. Influence sur le comportement de la vigne et la maturation du raisin. J. Int. Sci. Vigne Vin. 3:133-142. 351

Ummarino, I. and Di Stefano, R. 1997. Influenza del numero di semi per acino sulla composizione dell uva. Nota II. Riv. Vit. Enol. 3:9-23. Van Leeuwen, C., Trégoat, O., Choné, X., Jaeck, M.E., Rabusseau, S. and Gaudillère, J.P. 2003. Le suivi du régime hydrique de la vigne et son incidence sur la maturation du raisin. Bull. OIV, 867:367-379. Tables Table 1. Soil texture of each vineyard used in the study. Location Sand % 41 67 63 Silt % 48 16 22 Clay % 11 17 15 Table 2. Rainfall Huglin Index and mean July to August temperature at the three locations used in the study. The mean column is the average value from 1980 to 2002. Location Rainfall (mm year -1 ) Mean 2003 1238 709 767 704 566 535 Rainfall 2003 April-Aug. (mm) 279 262 123 Mean Huglin Index temperature July-August (C ) Mean 2003 2003 2248 2447 24.5 2341 2537 24.9 2572 2603 28.7 Table 3. Applied water amounts (L vine -1 ) for each irrigation treatment at the three locations. Treatments T1 0 48 66 T2 21 82 89 T3 38 109 120 352

Table 4. Must characteristics and yield components of Sauvignon blanc as a function of location and irrigation treatment. Sugar ( Brix) TA (g L-1) ph Berry wt (g) Cluster wt (g) Yield (kg vine-1) Prun. wt. (kg vine-1) Ravaz index Treatment ** ** ** n.s. ** * ** n.s. T1 20.34 a 5.33 a 3.54 b 1.26 127 a 2.04 a 0.72 a 2.86 T2 22.11 b 5.06 a 3.52 b 1.31 129 a 2.26 a 0.77 b 2.98 T3 21.65 b 6.70 c 3.42 a 1.43 147 b 2.63 b 0.86 c 3.26 Location ** ** ** ** ** ** ** ** 18.56 a 7.24 c 3.36 a 1.91b 144.0 b 3.13 b 1.16 c 2.91 b 23.34 c 5.58 b 3.50 b 1.09 a 120.2 a 1.41 a 0.62 b 2.26 a 22.20 b 4.27 a 3.61 c 0.99 a 140.6 b 1.82 a 0.46 a 3.90 c Interaction ** ** ** n.s. ** n.s. n.s. ** ns, *, **: not significant, significant at P 0.05 and 0.01, respectively Table 5. Aroma compounds in the must of Sauvignon blanc grapevines as a function of location and irrigation treatment at harvest (µg kg -1 fresh wt.). -------------------- ------------------ ------------------ Compound Aliphatic alcohols 43 44 48 118 135 184 134 108 128 Linalool & derivates 359 392 26 225 192 204 367 306 360 α-terpineol & derivates 517 304 184 374 390 258 579 422 433 Geraniol & derivates 165 140 88 110 101 148 140 129 117 Monoterpenes 1041 836 536 710 684 611 1087 857 911 Benzoic compounds 2329 2147 1076 1077 863 804 1502 1465 1245 Norisoprenoids 991 723 377 708 547 542 923 663 871 Table 6. Aroma compounds in the must of Sauvignon blanc grapevines as a function of location and irrigation treatment at harvest (µg 100 berries -1 ). ------------------ ------------------ ------------------ Compound Aliphatic alcohols 7.8 8.4 9.6 13.8 14.8 19.5 11.8 10.1 14.8 Linalool & derivates 64.9 75.5 52.6 26.2 21.0 21.7 32.4 28.4 41.5 α-terpineol & derivates 93.4 58.6 36.7 43.4 42.5 27.3 51.0 39.3 49.9 Geraniol & derivates 29.9 27.0 17.6 12.8 11.1 15.8 12.3 83 13.5 Monoterpenes 188.2 161.2 106.9 82.4 74.6 64.8 95.7 76.0 104.9 Benzoic compound 421.0 413.6 214.7 125.0 94.2 85.3 149.4 146.5 173.8 Norisoprenoids 179.2 139.3 75.2 82.2 59.7 57.5 86.5 66.7 100.2 353

Table 7. Soil water availability measured at the location as a function of irrigation treatment. Values are the means of weekly gravimetric measurements at a depth of 30 and 60 cm. Volumetric soil water content at -0.033 MPa is 29.7 %vol. and at -1.5 MPa is 13.3 %vol. Growth stage Available water % fruit set-veraison 32 32 32 veraison-harvest 11 20 29 Figures 1.8 Ψstem (-MPa) 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 199 206 213 220 226 235 188 196 205 212 221 231 Ψstem (-MPa) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 T1 T2 T3 187 195 203 210 216 223 Day of year Fig. 1. Stem water potential of Sauvignon blanc as a function of location, Day of Year and Irrigation treatment. Bars represent one standard error (See Materials and Methods section for description of locations and irrigation treatments). 354

25 12 23 A 10 B Brix 21 g/l 8 19 6 17 Treatment: 4 Treatment: 3.7 ph 3.6 3.5 3.4 3.3 3.2 C A: sugar content B: titratable acidity C: ph 3.1 Treatment: Fig. 2. Must analysis measured at harvest. Bars represent 95.0 percent LSD intervals. Cluster weight Pruning weight 180 1.6 160 1.4 1.2 g 140 kg 1 120 0.8 0.6 100 Treatment: 0.4 Treatment: Fig. 3. Cluster and pruning weight measured at harvest. Bars represent 95.0 percent LSD intervals. 355

Sulphur comp. Global evaluation 100 80 60 40 20 0 Fruit T1 T2 T3 Herbaceous Elder Fig. 4. Wine taste analysis from fruit harvested at the location. 356