Evaluación de una red de sensores inalámbricos de temperatura de bajo costo para la gestión de la madurez en un viñedo cv. Cabernet Sauvignon

36 p.Un estudio se llevó a cabo durante la temporada 2016-2017 con el objetivo de implementar una red de sensores inalámbricos de temperatura de bajo costo para la evaluación de un modelo de predicción de madurez en función de la acumulación de Grados día (Base 10ºC). Para esto, los sensores fueron instalados en un viñedo comercial (Vitis vinifera cv. Cabernet Sauvignon) de 4,5 ha perteneciente a la viña San Pedro, localizado en el Valle de Pencahue, Maule, Chile (35°20'36.00"S, 71°46'42.19"O, 86 m.s.n.m). Para llevar a cabo esta evaluación se definieron cuatro tratamientos de riego con dos repeticiones. Los umbrales asociados a cada tratamiento fueron definidos en base al potencial hídrico de xilema (x), siendo T1= 0,6 MPa, T2= 0,8 MPa, T3= 1,0 MPa y T4= 1,2 MPa. En cada punto de medición se realizaron semanalmente (desde el periodo de pinta hasta la cosecha) mediciones de; temperatura (ºC), sólidos solubles (ºBx), pH y peso de bayas (g). La temperatura obtenida desde la red de sensores fue comparada con mediciones obtenidas desde una estación meteorológica automática (EMA) localizada dentro del predio de estudio. Los resultados muestran que el modelo fue capaz de predecir de manera precisa la acumulación del contenido de azúcar (ºBrix) en las bayas. Por otra parte, los tratamientos hídricos no tuvieron un efecto sobre la precisión del modelo, debido a que este se calculó en una etapa en la cual el desarrollo de las bayas se vuelve mayoritariamente dependiente de la temperatura. Palabras clave: Variabilidad espacial, Sensores inalámbricos, modelos de madurez en vides. /ABSTRACT: A study was carried out during the 2016-2017 season with the aim of implementing a lowcost temperature sensor network to evaluate a prediction model of maturation based on the accumulation of Growing Degree Days (10ºC Base). For this, a network of sensors was installed on a commercial vineyard (Vitis vinifera cv. Cabernet Sauvignon) of 4,5 ha, from the San Pedro Vineyard, located on the Pencahue Valley, Maule, Chile (35°20'36.00"S, 71°46'42.19"O, 86 m.s.n.m). Four irrigation treatments were implemented, with two repetitions each. The thresholds associated to each treatment were defined according to the stem water potential measurements (x), being T1= 0,6 MPa, T2= 0,8 MPa, T3= 1,0 MPa y T4= 1,2 MPa. At each measuring point, weekly measurements (from veraison to harvest) of temperature (ºC), soluble solids (ºBx), pH and berry weight (gm) were performed. Temperatures from the sensor network were compared with measurements from an automatic weather station (EMA) located within the study site. The results show that the model was able to accurately predict the accumulation of sugar content (ºBrix) of the berries. On the other hand, the irrigation treatments had no effect on the precision of the model, given that it was calculated during a period where the berry development becomes mainly temperature-dependent. Key words: Spatial variability, Wireless sensors, vine maturity mode

Evaluación de un modelo de fenología en vid (Vitis vinifera) cv. Cavernet Sauvignon y su relación con la variabilidade espacial del cuartel vitícola

53 p.Con el objetivo de evaluar un modelo de fenología en vid y estudiar los principales factores que inciden en la variabilidad espacial de la evolución fenológica de un cuartel vitícola, se realizó un estudio en un cuartel cv Cabernet Sauvignon de 1,56 ha ubicado en la Estación Experimental Panguilemo, Talca (35°22,2’ S, 71°35,39’ O, 121 m.s.n.m), durante la temporada 2009-2010. Se efectuaron registros periódicos de fenología (cada 15 días) utilizando la escala propuesta por Eichhorn y Lorenz modificada por Coombe (1995) en una grilla regular geo-referenciada de 18 puntos. Además, se midió la expresión vegetativa (largo de brote) y el potencial hídrico del xilema al mediodía en una grilla regular de 59 puntos, en cuatro periodos fenológicos claves de la temporada. Las variables edáficas medidas correspondieron a textura, densidad aparente, capacidad de campo y punto de marchitez permanente en los mismos 18 puntos utilizados para la fenología. La información recolectada fue sometida a un análisis descriptivo multivariado, análisis geo-estadístico y cartográfico para determinar la estructura espacial de las variables medidas. Los resultados mostraron que la fenología de la vid presenta una variabilidad espacial importante dentro del viñedo, observándose una estructura espacial bien definida al interior del cuartel durante toda la temporada, esta información permitió delimitar dos zonas de manejo, las cuales presentaron diferencias de hasta 15 días en el desarrollo fenológico de las plantas. El principal factor de variación identificado que explica esta variabilidad correspondió a las condiciones de suelo, las cuales influenciaron la expresión vegetativa, el estado hídrico y la fenología. El modelo de fenología propuesto por Ortega et al. (2002) fue evaluado en las 2 zonas definidas en el análisis espacial, observándose un alto grado de ajuste en ambas zonas, con valores de coeficiente de determinación (R2) y eficiencia del modelo superiores a 98% y 0,96, respectivamente, y desviación estándar del error (DEE) inferior a 1,15 en ambos casos. Los resultados anteriores sugieren que el modelo de fenología evaluado presenta un alto grado de ajuste, incluso en condiciones de alta variabilidad espacial. Palabras Claves: fenología de la vid, modelos de fenología, agricultura de precisión, variabilidad espacial./ ABSTRACT: In order to evaluate a grapevine phenology model and study the main factors affecting spatial variability of phenological development of a vine plot, a study was carried out on a 1.56 ha commercial Cabernet Sauvignon vineyard located in Talca, Maule Region of Chile (lat. 35° 22.2' S, long. 71 ° 35.39' W, 121 m.a.s.l.) during the 2009-2010 growing season. Phenology measurements were collected fortnightly using the Eichhorn-Lorenz scale modified by Coombe (1995) over a regular geo-referenced 18-points-grid. Also were measured vegetative expression (shoot length) and midday stem water potential over a regular 59-points-grid in four key phenological stages of the season. Soil variables measured were texture, bulk density, field capacity and wilting point in the same 18 points used for the phenology assay. The information collected was submitted to a multivariate descriptive analysis, geostatistical analysis and mapping to determine the spatial structure of measured variables. Results showed that grapevine phenology has an important spatial variability within the vineyard, with a well-defined spatial structure inside the vine plot, allowing to delimit 2 management zones with differences of up to 15 days in the phenological development of the plants. The main factor explaining this variation was variability in soil conditions, which influenced vegetative expression, plant water status and phenology. Phenology model proposed by Ortega et al. (2002) was evaluated on the 2 zones defined in spatial analysis, being observed a high degree of adjustment in both areas, with values of coefficient of determination (R2) and model efficiency above 98% and 0.96 respectively, and standard deviation error (DEE) lower than 1.15 in both cases. These previous results suggest that the phenology model tested has a high degree of adjustment, even at high spatial variability conditions

Influence of Type of Management and Climatic Conditions on Productive Behavior, Oenological Potential, and Soil Characteristics of a ‘Cabernet Sauvignon’ Vineyard

(1) Background: Degradation of soils and erosion have been described for most of the soils presented along the Maule Valley. Organic and integrated management promotes agroecosystem health, improving soil biological activity. Due to this, the aim of this research was to study the effect of organic, integrated, and conventional management on the productive, oenological and soil variables of a vineyard cultivated under semiarid conditions during 5 consecutive seasons; (2) Methods: Yield, grape and wine oenological, and soil physicochemical parameters were evaluated. Bioclimatic indices were calculated in the studied seasons; (3) Results: Conventional management allowed to improve yield and the number of bunches per vine compared to organic management. However, this latter enhanced mineral nitrogen and potassium content in soil. Based on bioclimatic indices, heat accumulation improved number of bunches per plant and most of the soil physicochemical parameters; (4) Conclusions: Organic management improved the accumulation of some microelements in soils at the expense of yield. Organic matter decreased along the study was carried out. Season was the conditioning factor of the variability of most of the studied parameters, while the interaction between season and type of management affected soluble solids, probable alcohol and pH in grapes, and total polyphenol index and pH in wines

Spatial Variability of Production and Quality in Table Grapes ‘Flame Seedless’ Growing on a Flat Terrain and Slope Site

(1) Background: Precision agriculture has been used mostly to study spatial variability in vineyards for winemaking. Nevertheless, there is little available information on the impacts of its use on table grape vineyards under different slope conditions. (2) Methods: The aim was to study the spatial variability of production and berry quality in ‘Flame Seedless’ vines established on a flat (3% slope) and sloping (23% slope) terrain in the Chilean hyper-arid northern region. (3) Results: The results showed that in both vineyards, the measured variables presented a high spatial variability according to their coefficient of variation, being higher in slope than in the flat vineyard. The geostatistical analysis showed that 82% of the measured variables presented a strong spatial dependence in the slope vineyard, whereas 45% and 55% of the variables measured in the flat vineyard presented strong and moderate spatial dependence, respectively. Elevation was related to berry quality parameters in both vineyards, while trunk vine circumference was related to berry quality for the slope vineyard and to yield for the flat vineyard. (4) Conclusions: There is an important spatial variability in table grape vineyards mostly those cultivated on slope sites. Therefore, precision agriculture tools can be useful for zoning table grape vineyards, and thus improving both economic returns of viticulturists and sustainability

Monofilament Shading Nets Improved Water Use Efficiency on High-Temperature Days in Grapevines Subjected to Hyperarid Conditions

(1) Background: Table grapes are often subjected to thermal stress during the growing season, affecting their production. Shading nets utilization has been proposed as an alternative to face this problem, but there is little available information about their effectiveness in hyperarid conditions. INIA-G2 vines were covered with kristall-colored mesh of 8% shade, and their ecophysiological responses were compared to uncovered vines during the daily cycle of two days with contrasting thermic conditions. (2) Methods: Net assimilation rate (AN), stomatal conductance (gs), transpiration (E), instantaneous water use efficiency (WUE: AN E−1), stem water potential (Ψs), air temperature (Ta) and vapor-pressure deficit (DPV) were determined in daily cycles (from 06:00 to 20:00 hrs) on two thermally contrasting days (330 DOY at 29.4 °C and 345 DOY at 22.6 °C) on grapevines without water restriction. (3) Results: The Ψs was not affected by treatment and day of measurement; nevertheless, AN and gs were statistically lower during 330 than 345 DOY (31% and 44% decrease, respectively). The covered vines presented less restrictive climatic conditions in terms of DPV in both DOY, reaching higher WUE values at 10, 12 and 14 h, which was associated with a decrease in E. (4) Conclusions: These results suggest that the use of shading nets can be an interesting alternative to cope with high temperatures in viticulture, improving the water use efficiency of vines. These are the first published results about the viticultural performance of the INIA-G2 variety

Leaf-to-Fruit Ratios in Vitis vinifera L. cv. “Sauvignon Blanc”, “Carmenère”, “Cabernet Sauvignon”, and “Syrah” Growing in Maule Valley (Chile): Influence on Yield and Fruit Composition

A trial was conducted during the 2005–2006 season in order to determine the effects of different leaf-to-fruit ratios on yield components and fruit composition in four Vitis vinifera L. cultivars. The treatments consisted of selecting shoots of four lengths (>1.3 m, 1.3–0.8 m, 0.8–0.4 m, and <0.4 m) with two crop levels (1–2 clusters/shoot), which allowed defining eight ratios. Berry composition and yield components were measured. The treatments affected the accumulation of soluble solids in “Sauvignon blanc”, “Cabernet Sauvignon”, and “Syrah”, delaying it as the ratio decreased. All yield components were affected in “Sauvignon blanc”, while bunch weight and the number of berries per bunch were altered without a clear trend. None of the yield components were affected in “Cabernet Sauvignon”, while the lowest ratio presented the lowest number of berries per bunch in “Syrah”. Total polyphenol index (TPI) was affected in “Carmenère” without a clear trend. A highly significant correlation was found between shoot length and leaf area in all studied cultivars. As the ratio increased, the shoot lignification increased in “Sauvignon blanc”. However, studies must be conducted during more seasons to establish better conclusions about the effects of leaf-to-fruit ratios on yield and fruit composition

An overview about the impacts of agricultural practices on grape nitrogen composition: Current research approaches

Nitrogen is a structural component of proteins, nucleic acids, chlorophyll, hormones and amino acids. The last one and ammonium are important primary metabolites in grapes and are key compounds in winemaking since they are primary sources for yeast fermentation. Currently, grape quality has been affected due to the negative impacts of global warming and anthropogenic activity. Certain studies have reported a significant decrease in the free amino acids content and an increase in berry soluble solids and in proline biosynthesis in grapes in some grapevine varieties cultivated under warm climate conditions and water restriction. Proline is not metabolized by yeasts and stuck and sluggish fermentations can occur when the content of yeast assimilable nitrogen is low. Nitrogen composition of grape is mainly affected by variety, edaphoclimatic conditions of the vineyard and agricultural practices performed to the grapevines. This review summarized the most current research carried out to modify the nitrogen composition of the grape and give an overview of the technical and scientific aspects that should be considered for future research in this field.Peer reviewe

Methyl Jasmonate Applications in Viticulture: A Tool to Increase the Content of Flavonoids and Stilbenes in Grapes and Wines

Recently, the interest in methyl jasmonate (MeJ) has increased in viticulture due to its effects on the synthesis of phenolic secondary metabolites in grapes, especially of anthocyanins, flavonols, and stilbenes derivatives, naturally occurring or synthesized, in berries in response to MeJ application to grapevines. These metabolites help to define sensory characteristics of wines by contributing to their color, flavor and mouthfeel properties, and to derive potential beneficial health effects due to their consumption. This review offers an overview of the importance of these phenolic compounds in grape and wine quality, in association with the MeJ supplementation to grapevines, and also considers their natural biosynthesis in grapes. On the other hand, this review describes the adaptation mechanisms induced after the grapevine elicitation. In addition, this report addresses the effects of MeJ over other aspects of Vitis immunity and its association with phenolic compounds and summarizes the recently published reports about the effects of exogenous MeJ applications to grapevines on grape and wine quality

Modifications Induced by Rootstocks on Yield, Vigor and Nutritional Status on Vitis vinifera Cv Syrah under Hyper-Arid Conditions in Northern Chile

Hyper-arid regions are characterized by extreme conditions for growing and lack of water (<100 mm annual rainfall average), where desertification renders human activities almost impossible. In addition to the use of irrigation, different viticultural strategies should be taken into account to face the adverse effects of these conditions in which rootstocks may play a crucial role. The research aim was to evaluate the effects of the rootstock on yield, vigor, and petiole nutrient content in Syrah grapevines growing under hyper-arid conditions during five seasons and compare them to ungrafted ones. St. George induced lower yield than 1103 Paulsen. Salt Creek induced higher plant growth vigor and Cu petiole content than ungrafted vines in Syrah, which was correlated to P petiole content. However, Salt Creek and St. George rootstocks induced an excess of vigor in Syrah according to Ravaz Index. Rootstocks with V. berlandieri genetic background should be used in Syrah growing under hyper-arid conditions to maintain adequate levels of plant vigor and to avoid deficiencies or toxicity of macro and micronutrients

Study of Volatile Organic Compounds of Two Table Grapes (cv. Italia and Bronx Seedless) along Ripening in Vines Established in the Aegean Region (Turkey)

(1) Background: Italia is a seeded grape variety widely cultivated in the Aegean Region in Turkey, whereas Bronx Seedless is a seedless grape variety, preferred by consumers due to its pink berries and interesting flavor. The goal was to study the volatile compounds of these table grapes throughout berry ripeness. (2) Methods: The volatile compounds were analyzed by GC-MS in six different phenological stages (3) Results: Bronx Seedless grapes presented a higher content of seven terpenes, three aldehydes, one fatty acid, three alcohols, one C6 compound, total aldehydes and total alcohols, and a lower content of eleven terpenes, one fatty acid, four esters, one alcohol, four C6 compounds and its total content than Italia table grapes. The concentration of most of the volatile compounds analyzed increased from “begin of berry touch” to “berries ripe for harvest” stages. Terpenes content in both varieties at harvest was lower than 1.0 mg L−1. β-ionone presented the highest odor activity value (OAV) in both varieties. Bronx Seedless grapes presented higher OAV for (Z)-3-hexenal and cedrol, and lower hexanal to (E)-2-hexenal ratio than Italia grapes. (4) Conclusions: Both varieties could be classified as neutral aromatical varieties and it is probable that to achieve a better aromatic quality, Bronx Seedless should be harvested later than Italia