Terroir 1996 banner
IVES 9 IVES Conference Series 9 Ripening characterization and modelling of Listan negro grape in Spain using a regression analysis

Ripening characterization and modelling of Listan negro grape in Spain using a regression analysis

Abstract

The professional winegrower usually selects the harvest date considering several elements, such as the vine stem and berry colour, the flavour, appearance and grain elasticity. Nowadays these elements have turned old fashioned.
Other professionals take into account the weather or even manpower availability, so it is mainly random which determines wine quality, as this depends on the raw material (quality) characteristics.
In order to palliate these practice posible negative effects, this work was based on the simple mathematical equation obtention which characterized the ripening of the most common grape variety at Tacoronte-Acentejo vineyard area to give both the winegrower and the oenologist a simple instrument to find out the best harvest date or to know the value of each traditional parameter according to the weather.
This work was done during the season from 1994 to 1998, in the period that starts with the verasion and ends with the ripening process. During this period samples were taken weekly. About ten grains by vine stem were taken from a whole of fifty, which were previously selected in vineyards grown in different parts of the wine region.
Once they were in the laboratory and after getting the sample ready to obtain the grape must, multiple physicochemical analyses were done, from which we stand out the following ones: one hundred berry weight, total sample weight, total volume, grape must yield, soluble solids, probable alcoholic rate, pH, total acidity, tartaric acid, malic acid, bound and free volatile compounds (free and potentially volatile monoterpene grape flavourings), sodium, potassium, copper, iron, colour indicator parameters, from which only three have been used in this experiment, the sugar content given as probable alcoholic rate, pH and total acidity analysed using the Standard Methods.
After the systematic observation of the ripening curve lines, similar evolutive tendencies are found in the three analysed parameters. This tendency has been studied by comparing the curved line behaviour to a straight line, using a computerized calculation programme obtaining like this the slope, the ordinate in the origin and the coefficient of correlation r2 in each case. The equations found are of the type y = a + bx, were “y” represents the value of the physicochemical studied parameter and “x” the day from the verasion. The ordinate in the origin “a” will be the studied parameter value at the moment in which the first sample was taken, that is to say, in the verasion. Slope “b” indicates the studied parameter daily increase.
We have also found regression lines which allow the harvest date calculation for the probable alcoholic rate determined with 0,12 alcoholic / day slope for 500 m high vineyards areas or even higher. We have also established a linear pH relationship with the days up to the harvest, which depends on the vineyard height and a similar regression for the acidity has also been found.
Thus, knowing each parameter prediction equation, the winegrower will be able to know his harvest conditions. He will also be able to know the time left to obtain each analytical parameter wished value and so, the best optimum harvest date with more than a 90 % reliability.

DOI:

Publication date: February 24, 2022

Issue: Terroir 2000

Type: Article

Authors

García Fernández, M.J., González Mendoza, L.A., Pomar García, M.

Departamento de Ingeniería Química y Tecnología Farmacéutica
Facultad de Química. Universidad de La Laguna
Avda. Astrofísico Francisco Sánchez, s/n

Tags

IVES Conference Series | Terroir 2000

Citation

Related articles…

Assessment of climate change impacts on water needs and growing cycle on grapevine in three DOs of NE Spain

This study assessed the suitability of grapevine growing in three DOs (Empordà, Pla de Bages and Penedès) of Catalonia (NE Spain) over the 21st century. For this purpose, an estimation of water needs and agroclimatic and phenological indicators was made. Climate change impacts were estimated at 1 km pixel resolution using temperature and precipitation projections from several general circulation models (GCM) and two climate change scenarios: RCP 4.5 (stabilization scenario) and RCP 8.5 (worst-case scenario). Potential crop evapotranspiration (following FAO procedure) and a daily water balance considering soil water holding capacity were used to estimate actual evapotranspiration of vines and, finally, water needs. Dynamics would be similar in the three DOs studied although the magnitude of impact differs. Water needs would be 2 and 3 times greater (ranging from 0 to more than 1500 m3/ha) than current water needs at both climate change scenarios. Moreover, blooming date would advance from 3 to 6 weeks, harvest date from 1 to 2.5 months, resulting in growing cycles from 10 to 80 days shorter. It should also be noted that frost risk would decrease from 6 to 76%, the number of days with temperatures above 30ºC during ripening would rise from 48 to 500% and tropical nights (minimum temperature >20ºC) at ripening would increase from 28 to 150%, depending on the scenario and the DOs. The impacts of climate change in the three DOs could result in significant limitations for grapevine cultivation and wine production if adaptive strategies are not applied. This result could serve as a basis for the design of specific and particular adaptation strategies to improve and maintain vineyards in the DOs studied and could be extrapolated to similar DOs and regions.

Climate, Viticulture, and Wine … my how things have changed!

The planet is warmer than at any time in our recorded past and increasing greenhouse emissions and persistence in the climate system means that continued warming is highly likely. Climate change has already altered the basic framework of growing grapes for wine production worldwide and will likely continue to do so for years to come. The wine sector can continue to play an important role in leading the agricultural sector in addressing climate change. From developing on…

Assessing the climate change vulnerability of European winegrowing regions by combining exposure, sensitivity and adaptive capacity indicators

Winegrowing regions recognized as protected designations of origin (PDOs) are closely tied to well defined geographic locations with a specific set of pedoclimatic attributes and strictly regulated by legal specifications. However, climate change is increasingly threatening these regions by changing local conditions and altering winegrowing processes. The vulnerability to these changes is largely heterogenous across different winegrowing regions because it is determined by individual characteristics of each region, including the capacity to adapt to new climatic conditions and the sensitivity to climate change, which depend not only on natural, but also socioeconomic and legal factors. Accurate vulnerability assessments therefore need to combine information about adaptive capacity and climate change sensitivity with projected exposure to new climatic conditions. However, most existing studies focus on specific impacts neglecting important interactions between the different factors that determine climate change vulnerability. Here, we present the first comprehensive vulnerability assessment of European wine PDOs that spatially combines multiple indicators of adaptive capacity and climate change sensitivity with high-resolution climate projections. We found that the climate change vulnerability of PDO areas largely depends on the complex interactions between physical and socioeconomic factors. Homogenous topographic conditions and a narrow varietal spectrum increase climate change vulnerability, while the skills and education of farmers, together with a good economic situation, decrease their vulnerability. Assessments of climate change consequences therefore need to consider multiple variables as well as their interrelations to provide a comprehensive understanding of the expected impacts of climate change on European PDOs. Our results provide the first vulnerability assessment for European winegrowing regions at high spatiotemporal resolution that includes multiple factors related to climate exposure, sensitivity, and adaptive capacity on the level of single winegrowing regions. They will therefore help to identify hot spots of climate change vulnerability among European PDOs and efficiently direct adaptation strategies.

Grapevine yield estimation in a context of climate change: the GraY model

Grapevine yield is a key indicator to assess the impacts of climate change and the relevance of adaptation strategies in a vineyard landscape. At this scale, a yield model should use a number of parameters and input data in relation to the information available and be able to reproduce vineyard management decisions (e.g. soil and canopy management, irrigation). In this study, we used data from six experimental sites in Southern France (cv. Syrah) to calibrate a model of grapevine yield limited by water constraint (GraY). Each yield component (bud fertility, number of berries per bunch, berry weight) was calculated as a function of the soil water availability simulated by the WaLIS water balance model at critical phenological phases. The model was then evaluated in 10 grapegrowers’ plots, covering a diversity of biophysical and technical contexts (soil type, canopy size, irrigation, cover crop). We identified three critical periods for yield formation: after flowering on the previous year for the number of bunches and berries, around pre-veraison and post-veraison of the same year for mean berry weight. Yields were simulated with a model efficiency (EF) of 0.62 (NRMSE = 0.28). Bud fertility and number of berries per bunch were more accurately simulated (EF = 0.90 and 0.77, NRMSE = 0.06 and 0.10, respectively) than berry weight (EF = -0.31, NRMSE = 0.17). Model efficiency on the on-farm plots reached 0.71 (NRMSE = 0.37) simulating yields from 1 to 8 kg/plant. The GraY model is an original model estimating grapevine yield evolution on the basis of water availability under future climatic conditions.  It allows to evaluate the effects of various adaptation levers such as planting density, cover crop management, fruit/leaf ratio, shading and irrigation, in various production contexts.

Effect of vigour and number of clusters on eonological parameters and metabolic profile of Cabernet Sauvignon red wines

Vegetative growth and yield are reported to affect grape and wine quality. They can be controlled through different techniques linked to vine management. The objective of this research was to determine the effect of vine vigour and number of clusters per vine on physicochemical composition and phenolic profile of red wines. The experiment was carried out during two vegetative cycles, with cv. Cabernet Sauvignon grafted onto Paulsen 1103. Three vine vigour were defined, according to shoot weight at previous harvests, being low, medium and high. Five treatments of number of clusters were used for each vigour, with 15, 22, 29, 36, and 45 clusters per vine. Grapes from all treatments were harvested in the same day from Brix and total acidity criteria. Thirty days after bottling, classical analyzes and phenolic compounds were performed. As results, different responses were obtained from each vintage. In 2020, a dry season from veraison to harvest, grapes and wines obtained from low vigour treatment and 45 clusters per vine was the highest in sugar and alcohol content respectively, while grapes and wines from high vigour and 15 clusters presented the lowest sugar and alcohol content. Total anthocyanins were higher in treatment with low vigour and 15 clusters, while the lowest amounts were found in low vigour with 45 clusters, as well as medium and high vigour with 36 clusters per vine. Total tannins were higher in high vigour with 22 clusters and medium vigour with 29 clusters, while were lower in low vigour with 36 clusters. In 2021, a wet season at harvest, responses were different, and great variations were observed between treatments. As conclusions, yield and vine vigour had strong influence on grape and wine quality, promoting different enological potentials on which can be indicated/used for aging strategies of red and even rosé wines.