Is Precision Viticulture Beneficial for the High-Yielding Lambrusco (Vitis vinifera L.) Grapevine District?

The best Lambrusco wines are often obtained by blending a representative of the Lambrusco family (i.e. Lambrusco Salamino) with a smaller fraction of Ancellotta, a teinturier variety possessing an extraordinary quality of accumulating color. Due to the economic importance of the Lambrusco business and the rising interest in precision viticulture, a two-year trial was carried out in seven vineyard plots growing both the named varieties. A RapidEye satellite image taken on 9 August 2018, led to vigor maps based on unfiltered normalized difference vegetation index (NDVI). In both the years, ground truthing was performed on the test vines chosen within each vigor area for soil features, vegetative growth, yield, grape, and final wine composition. For data pooled over sites and years, Ancellotta showed a very clear response to NDVA-based vigor mapping as low vigor areas always achieved improved ripening in terms of higher total soluble solids (+1.24 Brix), color and phenols (+0.36 mg/kg and + 0.44mg/kg, respectively), and lower malate (-1.79 g/L) vs high vigor. Such a behavior was shown even in those cases where NDVI of different vigor levels and pruning weight were not closely correlated and, most notably, low vigor matched with a slightly higher yield as compared to high vigor plots. Overall, the high yielding Lambrusco Salamino was less responsive in terms of vine performance and grape composition versus intra-vineyard variability. This study highlights that, in Ancellotta, adjusting the vine balance toward ostensible lower vigor (i.e pruning weight ≤ 1 kg/m) would result in a superior choice in terms of improved ripening and wine profiles would not be detrimentally impacted by the yield level which, in fact, increased in some cases.


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The essence of applying precision agriculture is that it takes into account in-field variability (McBratney 44 et al. 2005, Schieffer and Dillon 2014, Wolfert et al. 2017. Its characterization is left to a spatial and 45 temporal mapping of crop status, vegetative growth, yield, and fruit quality variables and paves the way 46 to the enticing prospect that the general negative traits usually bound to "variability" might turn into an 47 that the labeling of vigor areas without site-specific ground truthing can lead to meaningless or even 96 deceiving information. 97 Another item deserving clarification is assessing when intra-vineyard spatial variability is high enough 98 to warrant some forms of exploitation (i.e., selective harvesting) or correction (i.e., adopting variable rate 99 applications to let convergence towards the most desired vigor or yield level. Evidence has been provided 100 (Schaepman-Strub et al. 2006, Tanda andChiarabini 2019) that absolute values of NDVI cannot be directly 101 used to infer vigor simply because at the same NDVI value, quite different levels of vigor can be found due 102 to the interference of several factors such as ground resolution, modalities of image acquisition (i.e., 103 zenital vs inclined), composition of mixels (a pixel having a varying contribution of canopy and soil 104 reflection patterns), floor management, pruning type, and row orientation. 105 An ideal and still unexplored wine district to be assessed in terms of spatial variability by satellite 106 imagery is the Lambrusco area, extending for about 15,590 ha primarily in the Provinces of Modena and 107 Reggio Emilia in the Emilia-Romagna Region, mostly established on flat terrains. Lambrusco is a fairly 108 unique product and is renowned as a crisp, vividly colored, and sparkling red wine. Currently, it is the most 109 sold wine in large-scale retail trade and the HORECA channel in Italy and also boasts of increasing export 110 trends to South America, Russia, and Canada (as found in http://www.inumeridelvino.it). 111 The purpose of this study was the following: i) to provide ground truthing, on a two-year basis, of NDVI-112 based vigor maps created from satellite imagery in three different farms growing Lambrusco Salamino, 113 one of the best representative cultivars of the Lambrusco family and Ancellotta.; and ii) to determine if 114 and how assessed and ground truthed intra-vineyard variability should lead to a change in the current 115 cultural practices. 116 were chosen for a total of seven test parcels (three plots for Lambrusco Salamino and four plots for 121 Ancellotta). While general features of each vineyard are reported in Table 1, attention was given to 122

Materials and Methods
Ancellotta and Lambrusco Salamino due to their high acreage (4,635 and 4,085 ha for Lambrusco Salamino 123 and Ancellotta, respectively). Ancellotta and Lambrusco Salamino nicely complement each other in the "Reggiano", "Lambrusco Salamino di Santa Croce," and "Lambrusco di Modena" DOC appellations where 125 Ancellotta is allowed up to 15%. Ancellotta is a well-known, deeply-colored complementary variety 126 bringing more color, structure, and roundness to the wine smoothing down the high acidity of the 127 Lambrusco Salamino grapes. Mapped vineyards ranged from 0.4 ha to 1.3 ha in size and were all vertically 128 shoot positioned (VSP) types (Table 1). However, pruning systems were different ranging from VSP spur-129 pruned cordon at Pignagnoli to a traditional Sylvoz trellis at Sabbattini ending with a Casarsa system at 130 the Robuschi site. At Robuschi, data collection is limited to 2018 as very severe hail damage prevented 131 gathering reliable harvest data in 2019. 132 The minimum, mean, and maximum daily air temperature (°C) and daily rainfall (mm) from April 1 to 133 September 30 were measured in each season by a nearby weather station. 134 Vigor mapping and soil sampling. A multispectral remote image was taken on 9 August 2018, using a 135 satellite belonging to the RapidEye constellation and equipped with a 5 m ground resolution sensor. The 136 NDVI index was consequently calculated and vigor maps built according to the "equal area" algorithm 137 applied by the engineering company Studio TerraDat (Paderno Dugnano, Italy) resulting in the breakdown 138 of each parcel into three vigor classes corresponding to HV, MV, and LV (Figures 1 and 2). The 'equal area' 139 criterion was preferred in maps segmentation due to its intrinsic ability to describe more effectively rapid 140 and/or irregular changes in natural data and phenomena (Zhou et al. 2007). Absolute values of NDVI 141 ranges for each parcel and vigor level are reported in the captions of Figures 1 and 2 for both the cultivars. 142 The NDVI utilizes only two reflectance values, taken at the same time and for the same target area, 143 according to the equation NDVI = (ρNIR − ρR) / (ρNIR + ρR), where ρ is the spectral reflectance of the target 144 and the subscripts NIR and R denote the near-infrared (760-850 nm) and the red (630-685 nm) satellite's 145 spectral bands, respectively. The NDVI is a number ranging between -1 and +1 and quantifies the relative 146 difference between the near-infrared reflectance "peak" and the red reflectance "trough" in the spectral 147 signature. For the highly vegetated targets, the vigor level is high and the NDVI value is close to unity, 148 while for the non-vegetated targets, the vigor level is low and the NDVI value is close to zero (negative 149 values rarely occur in natural targets). 150 For each cultivar x farm x vigor level combination (2 x 3 x 4 to yield 18 cases in total), a soil sample 151 down to 120 cm depth was taken with a Dutch auger in the central part of a given vigor area and the mid-152 row alley on June 26 and 27, 2019. Each sampling point was geolocalized according to standard Datum 153 WGS, projection UTM, and fuse 32. Each soil observation was then classified based on the soil taxonomy to the family level (Soil Survey Staff 2014). Soil subsamples from 0-40 cm depth were then taken at ten 155 different positions around six of the 18 drilled holes and then reunited in a single composed sample per 156 position. These soil samples were then processed for standard chemical-physical analyses as reported in 157 Table 1S. 158 Vine assessment. Each vigor zone was divided into three blocks. For each block x vigor combination 159 four vines were randomly chosen (36 vines in total for each vineyard, 12 vines for each vigor class) to 160 collect data for ground truthing assessment. Each season, at the time of harvest, cluster number, and yield 161 per vine were recorded for each individually tagged vine and the mean cluster weight was calculated 162 accordingly. At the time of winter pruning, the total cane number per vine was taken and cane fruitfulness 163 was calculated. In November 2018, before performing winter pruning, the node number for every vine 164 left on the two-year-old wood was taken and, after pruning, the same counting was made of the newly 165 maintained spurs or canes. 166 Each season, the harvest was done when the Brix concentration in grapes was higher than 20 and 18 167 Ancellotta and Lambrusco Salamino, respectively. At that time, a 200 berry sample was taken from each 168 tagged vine assuring that variability due to the cluster position within the plant and the berry position 169 within the cluster were represented. After weighing the whole sample, a 50-berry subsample was used to 170 measure the concentration of total anthocyanins and phenols after Iland (1988), and the final data were 171 expressed as mg/g of fresh berry mass. The remainder of each whole sample was crushed and the 172 resulting musts were immediately analyzed for Brix, pH, and titratable acidity (TA). Brix concentration was 173 determined using a temperature-compensating refractometer (RX-5000 ATAGO U.S.A., Bellevue, WA), pH 174 was assessed with a pH-meter CRISON GLP 22 (Crison,Barcelona,Spain), and TA was measured by titration 175 with 0.1 N NaOH to a pH 8.2 endpoint and expressed as g/L of tartaric acid equivalents. 176 The quantification of organic acids was performed injecting musts into HPLC after filtering through a 177 0.22μm polypropylene filter. The identification was performed by external calibration with standards and 178 concentration was calculated measuring the peak area and expressed in g/L. For this analysis, an Allure 179 Organic Acid Column, 300 × 4.6 mm, 5μm (Restek, Bellefonte, PA) was used. The separation was 180 performed in isocratic conditions using water, pH adjusted at 2.5 by adding ortho-phosphoric acid. The 181 column temperature was maintained at 30 ± 0.1 °C, 15μl of the sample was injected. The elution was 182 monitored at 200-700 nm and detected by UV-Vis absorption with DAD at 210 nm.
When the leaf fall was completed, the total cane number per vine was taken and the fresh weight of 184 the 1-year old wood was removed with pruning and recorded for both the main and lateral canes. 185 Thereafter, the vine fruitfulness was calculated as the clusters/cane ratio, whereas the Ravaz index was 186 calculated as the total yield-to-total pruning weight ratio (kg/kg). 187 Microvinifications. In two selected vineyards (LSSAB and ASAB2), 300 kg of grapes from HV and LV 188 blocks were harvested each year to conduct microvinifications in triplicate of single 100 kg batches at the 189 ASTRA laboratory (Tebano, Ravenna, Italy). After destemming and crushing, each batch was added with 190 sulfur dioxide (50 mg/L), ammonium phosphate (180 mg/L of nitrogen), and a suitable trade strain (30 191 g/100 Kg). The samples were then placed in a thermo-conditioned room (15-20°C) for the 192 fermentation/skin maceration phases and surveyed through the daily recording of the sugar content 193 (Babo) and temperature (°C). At 8-9% of alcohol content, the maceration was followed by sieving the solid 194 part (macerated peels and seeds) from the liquid phase (fermenting must). The raw wines were then 195 racked at the end of the fermentation process and added with sulfur dioxide (100 mg/L), gelatine (10 196 g/100 Kg), and bentonite (40 g/100 Kg). The wines were then stored at -5°C for not less than 3 weeks to 197 achieve tartaric stabilization. At the end of this phase, the stabilized wines were racked and newly added 198 with sulfur dioxide up to the maximum legal limit of 150 mg/L. Finally, the wines were filtered using 199 capsules of different materials and with different porosity of the membranes (up to 0.65 μm) to obtain a 200 limpid/shiny product. 201 Statistical analysis. Data were analyzed by a two-way analysis of variance (ANOVA) using Sigma Stat 202 3.5 (Systat Software Inc., San Josè, CA). The comparison of treatments was performed by  Neuman-Keuls test at P ≤ 0.05. Year × treatment interaction was partitioned only in the case of F test 204 significance. 205

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The weather course registered over 2018 and 2019 ( Figure S1) provided a good example of variability 207 over years. The year 2018 was quite standard for the area with a total GDD of about 2,000 °C from April 1 208 to September 30, moderate cumulative rainfall (276 mm) over the same period, and a quite long, hot, and 209 rainless period in summer until harvest. On the other hand, the year 2019 was un-seasonally cold and wet 210 until the end of May. Several rainstorms occurred also during the summer providing a remarkable 542 211 mm of total precipitation between April 1 and September 30.
Composite soil samples taken at 6 positions over different sites to represent either cultivar and vigor 213 level variability showed that although soils sampled at Sabbattini had overall higher sand fraction than 214 the other two sites, all of the samples shared features of no apparent limiting factors for root 215 development, abundant organic matter, and adequate total nitrogen availability (Table S1). Table S2 has 216 the details about soil horizon depths and the structures of eight out of 16 deep soil trenches that, at a 217 preliminary visual assessment, showed some kind of variation along the vertical profile. Most notably, in 218 both cultivars, the soil humidity status that was checked at the time of sampling indicated a humidity 219 status closer to the 1 (dry) category in the LV plots, whereas, in the HV plots, it approximated the 2 (slightly 220 humid) category with the status of "humid" (rank 3) scored at position 12 and a depth of 110-120 cm. 221 Despite large differences in retained bud load, cluster number and yield/ m of the row due to different 222 pruning system (spur-pruned cordons vs. long hanging canes held on a Casarsa trellis), the different vigor 223 zones mapped through NDVI calculation at Pignagnoli and Robuschi did not result in any significant 224 difference in terms of pruning weight, yield components, and the Ravaz index (Table 2). At Pignagnoli, no 225 significant year x vigor interactions occurred either. Despite the vigor results being quite well balanced 226 across the two sites (PW ranged from 630 to 800 g/m of cordon length), the high node fruitfulness of 227 Ancellotta explains tendentially high Ravaz index values. 228 A different scenario occurred at Sabbattini's locations where, in parcel 1, NDVI corresponded with 229 pruning weight that was significantly improved in the MV and HV treatments with both exceeding the 1.5 230 kg/m threshold. Interestingly though, some yield components followed a somewhat unrelated or inverse 231 relationship, whereby the yield/m was not related to NDVI, and the cluster weight decreased linearly 232 moving from LV to HV. Consequently, the Ravaz index was the highest in LV (8.36 kg/kg) and the lowest 233 in HV (5.47 kg/kg). 234 At Sabbattini 2, a relationship between yield/m and NDVI was observed as in the HV vines the yield/m 235 was 40% lower than the level in LV vines that was set at 5.64 kg/m (data averaged over the two seasons). 236 The specific yield components involved in such a response were cane fruitfulness and, in turn, the cluster 237 number/m that in HV was quite lower (31) than in MV and HV (44 and 46, respectively). Pruning weight 238 did not vary with NDVI levels; however, a significant year x vigor interaction occurred for this variable 239  indicates that, in general and regardless of the specific location, causal relationships were higher in 246 number and magnitude (Table 3) as compared to vegetative and yield variables. 247 At Pignagnoli, despite cane pruning weight and yield showing no apparent correlation with NDVI, LV 248 vines had higher Brix, tartrate/malate ratio and phenols than HV, and conversely lower TA and malic acid. 249 Overall, MV vines behaved quite similarly to HV vines. There were also significant year x vigor interactions 250 for TA, pH, and malic acid ( reported for Pignagnoli, as lack of any relationship between cane pruning weights and yield vs NDVI did 255 not prevent LV vines from reaching better maturity than either MV or HV, including total anthocyanins 256 (Table 3). Must composition at harvest at Sabbattini site 1 had an overall good correspondence with the 257 higher cane pruning weights measured in HV plots. Although Brix was not significantly affected, HV had 258 higher TA and malic acid, as well as lower total phenols than MV and LV. A quite similar response was 259 seen at Sabbattini site 2 where, for data pooled over the two seasons, HV vines originated decidedly less 260 mature grapes for most of the fruit ripening variables, including also total anthocyanins and phenols 261 concentration. TA showed a significant year x vigor interaction, confirming that in the wet and cooler 262 2019, TA of HV stayed above the 12 g/L threshold (Table 3). 263 Despite large variability in bud load/m, cluster number/m, yield/m, and Ravaz index, in no case were 264 there differences among NDVI-based vigor levels for vegetative and yield variables in the Lambrusco 265 Salamino cultivar (Table S3). At Pignagnoli, must composition at harvest was somewhat more responsive 266 to vigor levels, and interestingly, HV concurrently had higher TA and total anthocyanins than MV and LV 267 (Table 4). Single-year data (2018) of must composition at harvest available at Robuschi did not indicate 268 any consistent difference in ripening, whereas at Sabbattini differences were limited to lower Brix in HV 269 vs MV and LV and a reduced tartrate/malate ratio, primarily driven by slightly higher malic acid retained 270 in HV (Table 4). 271 Final wines composition for grapes taken from Sabbattini vineyards and representative of LV and HV 272 is reported in Table 5. The responsiveness of Ancellotta to the described intra-vineyard variability was 273 confirmed, overall. In both vintages and regardless of the quite sharp differences in the weather course 274 of each season, the true final alcohol content in LV was 1.22 and 1.56 Brix higher than that measured in 275 HV vines, and most importantly, highly desirable traits such as total anthocyanins and color intensity were 276 associated with lower vigor zones. Similar effects, although lower in magnitude, were seen for the wine 277 included both vine and soil pixels. Though, our NDVI ranges were very close to those calculated by the 283 above authors on 3 x 3 m and 5 x 5 m resampled images that were also cleaned to isolate pure vine pixels 284 only. Likely reason is that NDVI disturbance due to grassed inter-rows is high when the vineyard floor is 285 covered with dense vegetation, whereas under our operational condition vegetation was quite weak with 286 several yellow spots. 287 Over cultivars, out of seven tested vineyard plots, in only one case (Sabbattini 1 -Ancellotta) did NDVI 288 based vigor levels reflect a significant variation in one-year-old pruning mass. This outcome feeds two 289 possible hypotheses; either that "low", "medium", and "high" were overall representative of a scant 290 whole plot variability, or conversely that pruning weight might not be sensitive enough to detect vigor 291 differences. 292 About the first hypothesis, soil samples taken at different vigor plots showed, within each cultivar, 293 mild variation in terms of texture, nutritional status, and chemical variables (Table S1). However, in both 294 cultivars, soil profile investigated until 120 cm depth and classified for the status of the different horizons 295 showed that, in HV plots, soils were slightly deeper and more humid at the time sampling was made, 296 therefore potentially accounting for a somewhat different vine vegetative expression (Table S2). 297 With regard to pruning weight being a good predictor of vine vigor and/or vegetative capacity, older 298 work (Bates 2008) has shown, in Concord, a close correlation between pruning weight and total leaf area. 299 However, when it comes to the correlation between NDVI and pruning weight, the literature is anything of a given vigor parameter might depend upon the pruning type and especially bud load. In theory, moving 306 from a low to high bud load, the latter being representative of either mechanical or minimal pruning, due 307 to the increasing number of either main and lateral canes, wood maturation might get worse, leading to 308 significant self-pruning before the record of winter pruning is actually taken. An additional error is also 309 caused by the fact that, quite typically, the removed pruning mass does not take into account shoot mass 310 previously removed with trimming, which usually has a stronger impact in severely pruned training 311 systems that are conducive to high vigor of individual shoots. However, such a rationale is not confirmed 312 in our study, since the three chosen vineyards adopt different pruning systems covering a large variation 313 either for pruning length (short in spur-pruned cordons and long in Sylvoz and Casarsa trellises) and bud 314 load (Table 1). Moreover, in all the experimental sites considered as part of this study, canopy trimming 315 was performed several times over the season, leading to a much more standardized canopy shape and 316 volume at the end of the growing season, and especially at veraison when satellite imagery was acquired. 317 According to Taylor et al. (2013) this evidence suggests that bigger differences in plant growth and vigor 318 within the selected sites might be registered by mapping vineyards at different phenological phases, such 319 as before fruit-set or before trimming. Though, it should also be considered that even a nadir NDVI 320 determination performed at canopy growth completion on a VSP trellis still offers room to accommodate 321 variation in vine size mostly due to canopy thickness and, depending upon degree of laterals emission 322 after last trimming, colonization of some interrow spacing. Conversely, it is unlikely that variation is due 323 to canopy function as the image targets to top canopy section representing also the youngest canopy part 324 whose senescence process has not likely commenced yet. 325 On the other hand, despite pruning weight measurement being a quite straightforward procedure, it 326 is time consuming, and it could also be that sample size is not adequate to represent whole block wire of the trellis led to saturation problems which diminished when the target was a canopy area 332 featuring still growing shoots. 333 A quite peculiar aspect of our work when considering the response of Ancellotta was that, though the 334 NDVI derived vigor levels had, with few exceptions, poor correlation with either pruning weight or yield, 335 the overall grape composition response was, regardless of training systems, pruning type, and bud load, 336 in favor of the low vigor status. In fact in LV, Brix, malic acid, tartaric/malate ratio, total anthocyanins and 337 phenols in all cases showed a relative change in terms of "improved" ripening as compared to HV (i.e., 338 higher TSS, color, phenols, and tartare/malate ratio and lower malic), and in 18 cases out of 20 paired 339 comparisons (4 locations x 5 variables), such difference was significant. Pooling Ancellotta data over 340 different locations revealed that, to promote maturity, the Ravaz index should stay around 9-10 kg/kg and 341 pruning weight should not exceed 1 kg/m of cordon length. 342 However, the response observed on LV-Ancellotta is quite different from that of other studies where 343 low vigor was likewise associated with enhanced maturity. This has been reported for several conditions 344 and varieties, including for Barbera (Ferrer et al. 2020, Gatti et al. 2018, Kotsaki et al. 2020, Song et al. 345 2014, although in these studies low vigor also paralleled considerably lower yield. Our data show that-346 in terms of grand means over sites-LV-Ancellotta had a yield of 7.47 ± 1.19 kg/m vs. 6.91 ± 1.05 kg/m 347 and 5.98 ± 1.15 in MV and HV, respectively. These data look extremely promising for local growers, 348 especially in terms of the economic sustainability of a precision approach; improving maturity under no 349 change, or even a slight increase in yield, is a very desirable outcome and represents a very good example 350 of how intra-vineyard variability could be profitably exploited. No doubt the growing and ripening features 351 of Ancellotta would favor such a response: Ancellotta has been demonstrated to be a quite flexible 352 genotype in terms of variation of fruit composition variables vs. increasing yield: yield vs Brix were not 353 correlated (R 2 = 0.02) despite yield/m ranging between 3.4 and 9.6 kg/m, and the same applied to the 354 relationship of yield/m vs total anthocyanins (R 2 = 0.02). 355 The batch of data gathered on Ancellotta also sheds light on the usefulness of ground truthing for a 356 vigor level defined as "high" on an NDVI mapping assessment. Expected agronomic responses to "high" of HV Ancellotta vines observed in our study, though, still seems different from the two reported ones. 366 While it was ascertained that NDVI based high vigor led to inferior grape composition, the same high vigor 367 was decoupled from a yield response, and the highest yield levels were found on low vigor vines. This 368 behavior was seen at both Sabbattini sites, albeit under two probably different mechanisms; in Sabbattini 369 1 the inverse relationship between NDVI based vigor level and cluster weight suggests, on a two-year 370 basis, that cluster weight was limited by lower fruit-set due to competition exerted by excessive vegetative 371 growth (May 2004) at either MV or HV. Indirect confirmation is that neither shoot fruitfulness nor berry 372 weight was affected by vigor, and calculated berry numbers/clusters varied from a maximum of 128 in LV 373 to a minimum of 93 berries/cluster in HV. At the other Sabbattini site, a different mechanism is envisaged 374 to involve a likely biannual bearing pattern. In the year 2018, which had the features of a responsive year 375 in terms of yield, bud initiation conditions were likely less favorable due to a competitive vigorous growth 376 in HV (PW at 1.42 kg/m, Figure 3), that resulted in a lower actual shoot fruitfulness the next season (Table  377 3). 378 Despite vineyard design and cultural practices not being changed as a function of cultivar, overall 379 Lambrusco Salamino response to intra-vineyard variability was mild, and differences were much less at 380 both grape and wine compositional levels. The hypothesis that can be made to explain such differential 381 behavior hints at its different agronomic traits and the role that Lambrusco Salamino is expected to play 382 in a Lambrusco wine type. Lambrusco Salamino is historically considered the "yield" builder in such a 383 context, and older Lambrusco Salamino vineyards trained to the traditional Raggi Bellussi system or the 384 more recently introduced GDC quite easily reach 40 t/ha (Intrieri and Poni 1995). In the specific context 385 of our study, Lambrusco Salamino vine balance assessed over different sites and vigor levels was quite 386 different from Ancellotta; vigor is overall lower (0.65-0.70 kg/m range), the yield is much higher (9.4-10.3 387 kg/m range), and remarkably, Ravaz index is astonishingly constant around 18 kg/kg, suggesting a sort of 388 permanent over-cropping status. Under such high crop load status, it is also probable that vines are less 389 responsive to any factor that is able to alter vigor. Lambrusco Salamino proved to be extremely insensitive in terms of Brix response vs yield, showing essentially no change within the interval of 6.9 -14.1 kg/m (R 2 391 = 0.06). 392 Data need to be discussed also in terms of modifications to vineyard management that the Lambrusco 393 district could consider in light of the presented results. Due to the responsiveness of Ancellotta in terms 394 of the capacity of low vigor plots to improve either grape or wine composition without altering or even 395 slightly increasing yield, such an attitude should be exploited and managed. While the target is not to 396 benefitted from the fact that at the timing that images were captured mid rows in all cases were grassed, 404 thereby minimizing the interference of mixels where soil contribution is significant. 405

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NDVI based vigor mapping conducted, for two seasons, in three sites encompassing two cultivars 407 (Ancellotta and Lambrusco Salamino) and different pruning systems showed higher responsiveness by the 408 highly colored Ancellotta than the Lambrusco Salamino, marked by very high yield/m and Ravaz index 409 levels. The behavior observed in the "low vigor" Ancellotta plots allows foreseeing a vast improvement in 410 vineyard efficiency, as enhanced grape and wine composition was achieved without any significant change 411 in yield, which rather manifested an increasing trend. Ancellotta is currently grown across an area of about 412 4,100 ha and producers are many, quite small in size, mostly delivering their grapes to large cooperative 413 wineries. This seems an ideal condition for running a large-scale mid-resolution satellite image acquisition 414 and then quickly confirming, through proximal sensing aimed at providing an almost real-time estimation 415 of pruning weight, areas where urgent correction of unbalanced vigor is needed. 416 Conversely, Lambrusco Salamino, despite being grown in nearby parcels and trained to the same 417 training system, did not show significant vine performance differences across different NDVI based vigor levels, proving that ground truthing remains a necessary procedure to assess convenience for intra-419 vineyard variability exploitation or correction.  Table 1 Main vineyards features of each farm with specification of soil management (SM), irrigation system (if present) and day of harvest for each season (2018 and 2019).

Farm
Vineyard code In case of significance of F test, mean separation within columns and year factor was performed using the Student-Newman Keuls (SNK) test or t-test, respectively:* p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant.   In case of significance of F test, mean separation within columns and year factor was performed using the Student-Newman Keuls (SNK) test or t-test, respectively:* p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant. In case of significance of F test, mean separation within columns and year factor was performed using the Student-Newman Keuls (SNK) test.:* p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant.  Table 3 Pruning weight (PW), yield components, shoot fruitfulness and yield-to-pruning weight ratio (Ravaz index as kg/kg) measured in 2018-2019 seasons on twelve vines of Lambusco Salamino in each of the three identified vigor classes (HV = high; MV = medium and LV = low) at Pignagnoli, Robuschi and Sabbattini vineyards. In case of significance of F test, mean separation within columns and year factor was performed using the Student-Newman Keuls (SNK) test or t-test, respectively:* p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant.