Studying spatial and temporal variability of a 'Barbera' vineyard with traditional and precision approaches

Land is variable and vine performances reflect such variability. Precision viticulture, based on remote sensing and variable rate technologies, is a valuable tool for its description and management. Because vineyard monitoring can be accomplished through different platforms, a wide array of solutions is now available combining different spatial and spectral resolutions, revisit time and cost. Challenge is selecting the most sensitive and cost-effective solution for facing specific technical issues. The research aims at comparing the sensitivity of four different remote and proximal sensing platforms in detecting within-field vigor variability of a 'Barbera' vineyard established in the Colli Piacentini wine district (NW of Italy). A panel of 8 vines was selected for each of three vigor classes (LV = low, MV = medium and HV = high) as previously identified by a 5 m resolution vigor map referred to July 2014. In 2016, physiological, agronomical and enological parameters were measured. Remote (satellite and UAV acquisitions at 10, 6 and 5 cm resolution) and proximal images (approximately one reading per vine) acquired in July 2016 were processed by calculating vigor indices and validated according to field data. Seasonal trend of Sentinel-2 derived NDVI values was described for each vigor class. Results show LV and HV vines always demonstrated different growth, yield and ripening patterns. This variability was successfully detected by satellite imagery and close correlations between Sentinel-2 and SPOT6-derived NDVI values with vegetative, yield and grape composition parameters were found. Canopy Index provided by proximal sensor MECS-VINE\uae was highly sensitive to vigor variation at the single plant scale. Open source Sentinel-2 allowed separating HV and LV areas over season suggesting potential suitability for vineyard monitoring and management under the experimental conditions. More consistent results require long-term confirmation

Viticoltura di precisione: le mappe NDVI per fare qualità (prove nel Piacentino sul vitigno Barbera)

Nell’ultimo decennio va affermandosi un crescente interesse verso la viticoltura di precisione (Tysseire et al. 2007). Questa tecnica si prefigge di quantificare la variabilità spaziale e temporale del vigneto al fine di adottare una gestione agronomica differenziata mediante l’immissione di input, come acqua e concimi, in modo proporzionato e calibrato rispetto alla reale necessità delle viti. È noto, infatti, come diverse zone viticole siano caratterizzate da variabilità intra-parcellare che, in prima battuta, si manifesta sotto forma di diverso vigore vegetativo e che è principalmente attribuibile a variazioni della caratteristiche fisico-chimiche del suolo. È importante aggiungere che scelte inadeguate relative alle operazioni preliminari all’impianto (scasso, spianamenti, drenaggio ecc.) alla forma di allevamento e alla gestione della chioma possono sicuramente influenzare o, addirittura, incrementare la variabilità attribuibile ai soli fattori naturali (Poni et al., 2013). La viticoltura di precisione si propone, dunque, non tanto come tardivo rimedio a una incauta gestione del vigneto, quanto come valido strumento per caratterizzare e gestire la variabilità attribuibile a cause di origine naturale (Bramley and Hamilton, 2004). Ad oggi, la viticoltura di precisione si basa soprattutto sull’utilizzo di immagini multispettrali da remote sensing, acquisite da satelliti e da velivoli con o senza pilota (Matese e Di Gennaro, 2015) sebbene, recentemente, siano stati brevettati nuovi dispositivi di proximal sensing, più flessibili nell’utilizzo, basati su sistemi ottici, scansioni laser, e acquisizioni a ultrasuoni (Wei e Salyani 2004, Llorens et al. 2011, Tagarakis et al. 2013, Nuske et al. 2014, Diago et al. 2016). Indipendentemente dalla tecnica utilizzata per acquisire le immagini, le operazioni di post-processing riportano i dati al calcolo di un indice di vegetazione. Tra questi, il più comune è l’NDVI (Normalized Difference Vegetation Index) basato sulla misurazione della riflettanza nelle bande del rosso (R) e del vicino infrarosso (NIR) che viene proposto come buon indicatore della biomassa fotosinteticamente attiva, la quale, a sua volta, è correlata con la dimensione (vigore) e con la funzionalità della chioma (stato di salute e/o stress) (Bramley 2010). L’NDVI, quando rappresentato graficamente, permette di mappare un appezzamento in funzione di diverse classi di vigore; in seguito, queste andranno calibrate a terra tramite indicatori fisiologici e agronomici quali, ad esempio, il numero di strati fogliari, la superfice fogliare e il peso del legno di potatura. La viticoltura occidentale dei Colli Piacentini insiste principalmente su due serie pedologiche note come Terre rosse antiche e Terre argillose della Val Tidone. Quest’ultima è caratterizzata da grande disformità nei terreni. Si riporta, infatti, la coesistenza dei suoli denominati “Vicobarone”, profondi, a tessitura argillosa e con elevato tenore di calcare, e dell’unità pedologica “Montalbo”, meno profonda, a tessitura argillo-limosa, con presenza di scheletro ghiaioso. Questa netta differenza nella composizione dei suoli si riflette in risposte vegeto-produttive eterogenee delle piante. In particolare, la presenza di aree a diversa vigoria entro lo stesso appezzamento determina inevitabilmente una maturazione difforme delle uve. Pertanto, la variabilità intra-parcellare potrebbe essere semplicemente “sfruttata” a fini produttivi realizzando una vendemmia selettiva in base alle classi di vigore oppure, in alternativa, essere “corretta”, ad esempio, utilizzando tecniche di fertilizzazione a rateo variabile, allo scopo di ridurla facendola convergere verso la classe di vigore ottimale. Sulla base di queste premesse, nel biennio 2012-2013, è stata condotta, nella zona della Val Tidone, una prova di viticoltura di precisione volta a: i) valutare se sussiste e, se sì, in quale misura, una variabilità intra-parcellare tale da influenzare le performance vegeto-produttive di viti di Barbera coltivate in un appezzamento di piccole dimensioni rappresentativo della variabilità geo-pedologica del comprensorio; ii) individuare quale sia il grado di correlazione esistente tra l’indice NDVI e i parametri vegetativi e produttivi misurati al suolo, senza tralasciare le eventuali implicazioni su stato sanitario e qualità delle uve alla vendemmia

Vite, controllare la maturazione gestendo la chioma

Il cambiamento climatico rende sempre pi\uf9 complicata la contemporaneit\ue0 della maturazione tecnologica e fenolica. Una prova triennale dell\u2019Universit\ue0 di Piacenza ha verificato l\u2019efficacia della defogliazione alta in pre e post-invaiatura nel rallentare l\u2019accumulo degli zuccheri nelle uve in un vitigno a bacca bianca a maturazione precoc

High potential of variable rate fertilization combined with a controlled released nitrogen form at affecting cv. Barbera vines behavior

Variable rate technologies allow site-specific management of parcels characterized by different levels of vigor and/or yield. Fertilization based on actual plant needs is one of the most promising applications of precision farming aiming at improving efficiency, optimizing vine balance, as well as limiting environmental impact. Although this strategy appears suitable for developing new vineyard management models, few experiences validating this hypothesis are available in the literature. Based on a pre-trial remotely sensed vigor map (NDVI-derived, 5\u202fm resolution), a three-year study was performed in a Vitis vinifera L. cv. Barbera vineyard situated in the Colli Piacentini area. Vigor level (L\u202f=\u202flow, M\u202f=\u202fmedium and H\u202f=\u202fhigh) and fertilization technique (Standard, Variable Rate Application, and unfertilized Control) were the main factors in a randomized block design. The controlled release fertilizer Multicote\u2122 Agri ([NPK fertilizer 13-5-21\u202f+\u202f7MgO+14SO3 (Controlled Release Nitrogen >46% on the total nitrogen, with longevity 2\uf74 months), low in chloride] was used and the input rate calculated according to the N-supply. For each vigor level the study compared no fertilization (0\u202fkg/ha), standard supply (40\u202fkg of N /ha) and Variable Rate Application (VRA) supply delivering 0, 40 and 80\u202fkg of N/ha to H, M and L, respectively. Vine growth, yield, leaf nutritional status and fruit composition were assessed. Results show that the classified L vigor plots had significantly less growth (i.e leaf area or pruning weight per vine) than M and H vigor plots, whereas yield components and grape composition followed a linear variation with vigor. There was a large prevalence of vigor x technique interactions suggesting that VRA had a differential impact on vine behavior depending upon the initial level of vigor. For vegetative and yield parameters, in the L vigor vines, increased Multicote\u2122 Agri dosage delivered as control (0\u202fkg of N/ha), standard (40\u202fkg of N/ha) and VRA (80\u202fkg of N/ha) caused a very close and linear increase in total leaf and yield per vine, whereas, within the M and H vigor plots, the effect due to fertilization technique was very mild. Such a behavior was nicely mirrored by grape composition at harvest as, in L vines, applying 40 or 80\u202fkg of N in the form of Multicote\u2122 Agri induced a progressive and significant reduction in both must soluble solids and total anthocyanins concentration, although the oenological quality of the resulting must was still satisfactory and in compliance with the oenological target. The novelty of the present work is that, unlike previous variable rate fertilization attempts where a rapid nitrogen release fertilizer such as urea was used, L vigor vines showed a very prompt response to the amount of Multicote\u2122 Agri application, confirming higher effectiveness of this chemical form and higher flexibility in adjusting the level of vigor and yield according to specific needs. Conversely, when the initial level of vigor was medium or high, differential fertilization resulted in overall minor modifications of the vine behavior

Ground truthing and physiological validation of VIs-NIR spectral indices for early diagnosis of nitrogen deficiency in cv. Barbera (Vitis vinifera L.) Grapevines

Several narrow or broadband spectral indices can be calculated at varying spatial and spectral resolution, which can then be correlated with the physiological and nutritional status of the leaves. In a three-year trial carried out on fruiting, potted cv. Barbera grapevines subjected to full (N+) or no (N0) nitrogen supply, seasonal evolution of different leaf spectral indices were correlated with non-destructive chlorophyll readings (Minolta SPAD meter), leaf gas exchange, and vine performance. Throughout the entire trial, N starvation resulted in greater-than-proportional limitation of vine yield as compared to vegetative growth (55% compared to 26% less than values measured on N+). Indices calculated within the red-edge spectral domain had highest sensitivity to relative change between N+ and N0, also indicating that the promptest response was recorded at the median shoot zone level. Twelve broadband indices were linearly correlated with leaf blade N concentration at veraison, indicating that N values 64 1.8% of dry matter identify a limiting N status. Any of these indices collected at the leaf level can be reliably used as a non-destructive predictor of N availability, albeit due to significant between-year variation in their absolute values at a given N level, readings should always include a well-supplied N treatment

Long-term assessment of variable rate N-fertilization in a Vitis vinifera L. 'Barbera' vineyard

Variable rate technologies allow site-specific management of parcels characterized by different levels of vigor and/or yield. N-fertilization based on actual plant needs is one of the most promising applications of precision farming aiming at improving efficiency, optimizing yield-to-quality relationship as well as limiting environmental impact. Although this strategy appears suitable for developing new viticultural models, few experiences validating this hypothesis are available in literature. Based on a pre-trial remotely sensed vigor map (NDVI-derived, 5 m resolution) a four-year study was performed in a Vitis vinifera L. 'Barbera' vineyard situated in the Colli Piacentini wine district. Vigor level (L = low, M = medium and H = high) and fertilization strategy (standard, variable rate application, and unfertilized control) were the main factors in a randomized block design. For each vigor level the study compared no N-supply (0 kg ha-1), standard supply (60 kg ha-1) and VRA supply delivering 0, 60 and 120 kg ha-1 to H, M and L, respectively. Post-trial effects were assessed by remote and proximal sensing considering a 5 m multispectral image and a very high resolution characterization of the canopy growth, respectively. Vine growth, yield, leaf nutritional status and fruit composition were assessed. Results show that variability among vigor levels was significantly reduced over year 3 and 4, whereas effects related to fertilization strategy were often non-significant. The canopy index calculated by proximal sensing proved that VRA was able to reduce variability among vigor levels (CV=1.42%) vs. standard fertilization at 60 kg ha-1 (8.20%). Leaf area did not vary among strategies while N-fertilization affected yield and vine balance. Despite VRA increased yield as compared to Standard, technological and phenolic maturity was similar in both fertilization strategies. The VRA reduced N waste in H while vines from L blocks showed a low sensitivity to increased N-supply

Effects of calibrated delayed winter pruning on Vitis vinifera L. \u2018Pinot Noir\u2019 grapevines in relation to different training systems

Warming trends are challenging viticulture worldwide. The rise of temperatures recorded in most of traditional and new wine regions can be particularly detrimental for the production of sparkling wines, requiring moderate alcohol level and sustained acidity. The postponement of spur-pruning after bud-break has recently been proposed as a simple and inexpensive technique to delay ripening, exploiting the natural acrotony of the grapevine. A three-year trial was conducted in central Italy to assess if late pruning can successfully delay ripening in grapevines according to different training systems. Mature vines cv. Pinot Noir were subjected to the following treatments: winter spur pruning (WSP), delayed spur pruning (DSP), winter cane pruning (WCP), and delayed cane pruning (DCP). Delayed pruning was performed when shoots growing on apical nodes of unpruned canopies reached the stage of 3 unfolded leaves, as an average. During the season, phenological stages were monitored twice a week for both spurs and fruiting canes. Ripening kinetics were characterized from veraison until the end of the season. DSP and DCP significantly delayed bud-break and early phenological stages. Similarly, sugar accumulation was postponed and the drop of titratable acidity was successfully shifted by 12 and 7 days, respectively. At technological maturity of WSP and WCP vines, corresponding to the achievement of ~20\ub0 Brix, DSP and DCP significantly reduced total soluble solids (-4.6 and -1.6\ub0Brix, respectively) and maintained higher acidity (+5.2 and +2.9 g L-1). Accordingly, a 46 and 32% yield loss were recorded. In both training systems, delayed winter pruning can be a simple technique suitable for preserving must compositional characters required for sparkling wines