Vinodata

Chile, a winegrowing paradise

Chile, a winegrowing country

Ramón A. Rada M.

At present, world class fine wines are produced practically in all the winemaking countries around the world, and quality is constantly enhanced by the attitudinal changes of winegrowers to conform to market demands and to technological changes in every production area: a practically full control of production processes has become a fact with the passage of time. Naturally, there exist differences between the winemaking countries in the world, expressed in quality variation and, particularly, in production costs.

Specialist winemakers have a saying: “one cannot make good wine from bad grapes”, a statement that has been axiomatic since remote times. In effect, the production of quality wines depends directly on the quality of the raw material (grapes) and of the ensuing processes. Production of excellent quality grapes is the key factor for the production of top quality wines and grapegrowing conditions vary according to geographic location, the best of which are constantly sought after by winegrowers. Geographic location, soil composition and quality, altitude, maximum and minimum temperatures, quality and quantity of sunlight, seasonal precipitation, and climate in general are key factors in grape growing.

But, as is the case in different places in the world, there is an increasing tendency to battle against climate, use state of the art technology or science to prevent or solve problems generated by inadequate climate conditions or acts of nature that are detrimental to the healthy development of wine grapes. All this is possible, but will no doubt impinge upon production costs. This has led grape growers to search for privileged areas in which to produce top grade winegrapes that fulfil their genetic potential with a minimum of human intervention. There is a constant search for harmony between Vitis vinifera, human beings and nature on the part of vintners, as they are well aware that such harmony makes grapevines yield the best fruit at the lowest cost.

Notwithstanding, this harmony has been threatened by the global climate shifts of the past thirty years. These phenomena are becoming increasingly evident, stronger and more frequent throughout the world, especially in the traditional grape growing areas in Europe. This global climatic change becomes particularly manifest in summer, which is the period of active growth of the vine, with extremely hot temperatures and more frequent and intense rain; in the extremely cold and prolonged winters and the unusual and violent flooding in the springtime.

Ocean temperatures have increased by more than one degree in the last hundred years and we are entering a cycle of structural global climate changes. Specialists in charge of monitoring global climate changes agree that the countries located in the Northern Hemisphere will suffer most from global warming because in comparative terms this hemisphere has more land than ocean, and therefore lacks the moderating effect of ocean masses. For this reason, the battle that many winegrowers wage against climate change in the Northern Hemisphere has become increasing difficult and expensive, giving a clear advantage to Southern Hemisphere producers. Not only will climate change render production more difficult in traditional winegrowing areas; it will also create new production areas, improving production conditions in some cases, and hindering them in others.

In spite of these climate changes, there still exist in the world, and specifically in the Southern Hemisphere, areas that present privileged agro climatic conditions for Vitis vinifera grape growing that make it possible to produce exceptionally good wines at a lower cost. The Chilean winemaking areas are included in this group. Southern Hemisphere countries such as Australia, New Zealand, South Africa, Argentina and Chile are the most important and larger producers of low cost fruit, which is exported with increasing success and quantity to the markets of the developed countries of the Northern Hemisphere. Nature has blessed these Southern Hemisphere countries, and this is especially true in the case of Chile.

The advantages of Chile

Advantage is a concept that is defined according to a pattern of comparison and is an element that has a high subjective content. But, the emotional content of the term can be mitigated by listing the conditions that define it as such, which will also allow for the full expression of its potential.

This is the case of Chile. Chile has optimum natural conditions for Vitis vinifera to reach its full development potential. So, it is neither subjective nor emotional to say that in Chile the conditions obtain for producing the best wine grapes. It is only a matter of entrepreneurial activity, as has been the case with certain successful plantations, which have been recognised by foreign wine critics when referring to Chilean wines. This situation enables us to say that Chile has a relevant natural advantage in this specific area. In other words Chile exhibits notable comparative advantages due to the harmony existent in the Chilean territory between plant development and the proper terroir which conforms its surrounding. Comparative advantages had derive in addition, due to multiple reasons, into competitive advantages that will be difficult to match in other wine producing areas, which are related mainly to wine grapes production cost levels.

Geographic location and territorial structure

Chile is located between latitudes 17º30’ and 56º30’ S, and its wine growing soils are located between the Region of Atacama and the Malleco Valley in the Region of Araucanía, between latitudes 26º south and 39º37’ south. On the other hand, these wine growing areas are protected by natural boundaries: 1,000 kilometres of the Atacama desert, one of the driest in the world, to the north, the Andes Mountains to the east, the vast frozen Ice Fields in Patagonia, and finally by the Pacific Ocean to the west. This geographic isolation has always acted as a natural barrier against migrating plant diseases, and has defended against phylloxera, the fiercest of all grapevine diseases.

The country’s territorial structure consists of the Andes Mountains Range to the east, which in some parts reaches up to 6,960.8 metres above sea level (22,837 ft), in the Aconcagua summit; a long central depression that varies in altitude and morphology; the lower Coastal Range, and finally, the Pacific Ocean to the west. The presence of the Humboldt Current that follows the Chilean coastline and brings cold water from Antarctica collaborates in the generation of a beneficial mountain-ocean interaction, unique in the planet. Finally, it is important to point out that the transverse valleys that cross the country from mountain to sea contribute to the formation of a large diversity of microclimates.

Climate

Chile’s wine growing valleys have a temperate Mediterranean climate, with a long dry season and a rainy winter. The mean annual temperature is 14ºC, while the warmest month in the year is January, with an average temperature of 22ºC, and the coldest is July with an average temperature of 81°C. Precipitation levels are moderate with annual averages of approximately 400 mm in central Chile. Precipitation levels decrease from the coast to the intermediate depression, and then rise again in the Andes Mountains Range, thus originating the general bioclimatic lines of central Chile.

The night breezes that course down the Andean slopes blow from east to west, from mountain to sea, while in the daytime breezes blow from sea to mountain along the watercourses refreshing the fields, producing a beneficial change between day and nighttime temperatures, which results in an optimum thermal range. Thus, the high daytime temperatures and low nighttime readings contribute to yielding grapes with a greater concentration of aromas and flavours. The land located on the Andean foothills, which tends to have even lower nighttime temperatures owing to its closeness to the origin of the winds can reach a thermal range of over 20ºC. Low nighttime temperatures result in freshness levels that are notable when compared to those of other wine grape growers in the world. This freshness index is based on the number of hours that the plants, in this case grapevines, are exposed to nighttime temperatures ranging from 5ºC to 10ºC, which are essential for fruit quality.

Freshness indexes for different wine growing regions in the world:

Freshness Index
Napa Valley (California) 1.0
Valle del Maule / Maule Valley (Chile) 1.0
Valle de Cauquenes / Cauquenes Valley (Chile) 0.99
Valle de Colchagua / Colchagua Valley (Chile) 0.98
Valle del Maipo / Maipo Valley (Chile) 0.93
Valle de Casablanca / Casablanca Valley (Chile) 0.92
Valle del Limarí / Limarí Valley (Chile) 0.90
Valle de Rapel / Rapel Valley (Chile) 0.89
Tour / Tours (France) 0.87
Bordeaux / Bordeaux (France) 0.85
Cotes du Rhône / Cote du Rhône (France) 0.82
Mendoza / Mendoza (Argentina) 0.73
Provence / Provence (France) 0.63
Cape Town / Cape Town (South Africa) 0.71
Adelaida / Adelaide (Australia) 0.59
Toscana / Tuscany (Italy) 0.58
Milán / Milan (Italy) 0.42
Barrosa / Barrosa (Port Augusta, Australia) 0.37
Barcelona / Barcelona (Spain) 0.22

On the other hand, lack of precipitation during the grapevine’s active growth period results in a very rare incidence of other diseases such as oidium and other minor ailments, so that the grape reaches its final winemaking process free from toxic waste. The dry summer season is an additional reason for saying that Chilean grapevines are the healthiest in the world, because there is no rainfall during the grapevine’s active growth period that goes from November to April. Furthermore, the variety of climates present in the country and the enormous water reserves contained in the Andean Mountain Range, as well as the entire ecosystem, favour the successful growing of Vitis vinifera, making this country a paradise for winegrowing and production of fine wines.

Solar Radiation

Solar radiation in Chile stands out when compared with other wine growing areas in the world and is probably the most relevant differential advantage of the country, especially in the case of plants used to high radiation levels as is the case of vitis vinifera. Diverse studies have shown that in quantitative and qualitative terms and in terms of the number of lightdays and atmospheric clarity, light conditions in Chile are such that they have led to the installation of multinational astronomic facilities in the country. This quality of light favours plant photosynthesis, which is more efficient and efficacious than in other wine growing areas. This gives clear advantages to the qualitative production of wine grapes and, in turn, facilitate the development of elements favourable to human health in a striking proportion, as established in a recent study by the University of Glasgow (United Kingdom, 2001), which has led British physicians to recommend Chilean wines to fight cardiovascular diseases.

Solar radiation has wave and particle properties. This means we can describe it as a wavelength (l) measured in nanometers (nm) or as discrete units called photons. The energy (E) of a photon is related to its corresponding wavelength by means of the equation of Plank’s Law (E=hc/l), where h is the Planck constant (6.63 x 10-34) and c is the speed of light in a vacuum (3 x 108 x m s –1). Therefore, a red photon, which has a l=650 nm will possess an energy equal to E=3.06 x 10 –19j, and a blue photon, having a l=450 mn will have an energy equal to E=4.42 x 10 –19J, which demonstrates that photons having a shorter wavelength possess more energy that those of a longer wavelength.

On the other hand, the radiation that reaches crops can be divided into short wave radiation (between 300 and 3.000 nm) and long wave or heat radiation (above 3.000 nm). Within short wave radiation we find the photobiological spectrum than ranges from 300 to 800 nm. Its name is due to the fact that these wavelengths are responsible for most organic photobiological phenomena.

Plants like grapevines develop a metabolic cycle by means of which they fix carbon dioxide (CO2) taking from the atmosphere a three carbon sugar, triphosphoglyceric acid: fructose and the union of these two molecules originates glucose (C6H12O6) a six carbon sugar. The energy required to reduce carbon dioxide (CO2) to glucose (C6H12O6) and return oxygen (O2) to the atmosphere stems from energy-rich phosphoric esters (ATP) and reducing compounds (NADPH+) that are directly synthesized by the action of photon energy absorbed by the light collecting antennae found in chloroplasts and formed by chlorophylls, the green pigments characteristic of leaves. The chloroplasts are membranes contained in the leaf cells, where the photochemical process known as the light phase of photosynthesis takes place.

Photosynthesis is not limited to the production of glucose to be transformed into ethanol during fermentation. While the berries are growing, the carbon from the same photosynthetic glucose is used and practically all the other bio molecules included in the chemical composition of the berries are synthesised i.e. proteins, aminoacids, sugars, organic acids, lipids, phenols, terpens, pigments etc. On the other hand, the induction of the synthesis of several of these compounds as well as the velocity of the processes is controlled by solar radiation. Thus, the induction of this synthesis is controlled by the quality of radiation, whereas its velocity is controlled by thermal action, which controls the temperature of the grapes.

Plants have photoreceptor molecules in their leaves, their young shoots and in the epidermis of their fruits, and these are activated by the action of certain given wavelengths, originating photochemical processes that differ from the bioenergetics’ processes described above. These processes lead to the synthesis of an ample variety of components and to the production of morphological phenomena that control plant development and growth.

The main photoreceptor known in plants is the phytochrome, which, in the case of the grape-vine, and in its active form (Pfr) regulates the growth of the shoots, and the synthesis of pigments in leaves and berries, among other processes. The phytochrome becomes active on receiving a wavelength radiation of 660 nm (R660), in other words, it reacts to red light and this active form is rendered inactive (Pr) by infrared radiation of 730 nm (IR730). So, when the amount of red light is greater than that of infrared radiation, that is, when R660/IR730 > 1, the quantity of active form phytochrome will be high. On the contrary, when the amount of infrared radiation is greater than that of red light, which is when R660/IR730 < 1, the inactive form will predominate over the active form in the plant. The active form of the phytochrome regulates key enzymes in the metabolism of phenylpropanoids, a cycle that originates pigments like antocianines and flavonoids, and that also generates precursors for the synthesis of polyphenoles on the cellular walls of shoots, stalks and seeds.

Ultraviolet radiation with wavelengths of 300 to 400 nm also takes part in pigment induction and important photobiological phenomena. UV radiation for example, regulates the activities of the PAL and chalcon synthetase in the phenylpropanoid cycle, and is therefore essential in the synthesis of flavonoids and a variety of phenols and polyphenoles in leaves and berries. It is also important in the regulation of aminoacid metabolism (arginine, glutamine and proline) and of carotenoids (violaxanthine and zeaxantine) in the berries, all of which are important for the quality of wine. Similarly, the action of UV radiation on antioxidant mechanisms makes it a key factor for the activation of mechanisms that protect the cuticle of the berry against fungal attacks, as is the case of botrytis.

An intensity of 1,000 µmol PAR m-2 s-1, a solar radiation that is normal for the Central Zone of Chile, which has an R660/IR730 proportion of approximately 1.2, is beneficial not only because of its effect on the control of quantity of sugar and temperature of those organs. The active phytochrome of red radiation (R660) also controls the amount of antocians and phenols in the berry. Antocianine content grows with an increase in the proportion of active phytochrome, which improves the colour of the berries and the phenol content of seeds and epidermis.

To synthesise the 12 NDPH+ and 18ATP required to produce one glucose molecule in the leaf of a grapevine, the plant requires its light collecting antennae to absorb approximately 130 photons of active photosynthetic radiation, at wavelengths between 400 and 700 nm. Energy of three moles of photons is required to accumulate 1 gram of glucose during the period that goes from the véraison to the maturity of the berries (23º Brix).

For the production of a 750 cc bottle of a good Cabernet Sauvignon, 13. 5º GL (Gay-Lussac) 122 grams of glucose are required, and the sun will have provided about 516 moles of photons. The energy of the rest of the 506 moles of photons captured is dissipated through diverse energy transforming processes and elements for wine grapes. A mere 10 moles of photons of the best radiation really remain to be savoured in the wine. When we drink a glass of wine (250 cc) we can say that it gives us the energy equivalent to three moles of the best photons of the sun.

Photothermal Index

Photothermal indices have been designed to measure the integration of solar radiation, maximum and minimum temperatures in wine grape areas and to determine the potential development of grapevines. At the same time, they also enable us to compare different production zones and their ability to provide the parameters required for the growth of the grapevine. The photothermal index is calculated according to the following formula:

IFT= [LDi /24 (GD)]

Where LDi = number of daylight per day and GD = Degrees per day.

The photothermal Index is calculated by adding the proportion of LD1 over a 24 hour
period, multiplied by the total heat units. (Masle et al., 1989)

A degree day (GD) is an index used to express harvest maturity. The index is calculated by subtracting a base temperature of 10ºC from the average maximum and minimum temperatures in one day. Minimum temperatures lower than 10ºC are assimilated at 10 while maximum temperatures of over 30ºC are assimilated at 30. These substitutions are carried out to indicate that there is no appreciable development in plants in temperatures of under 10ºC or over 30ºC.

The degree day that appears in the formula for calculating photothermal indices is calculated as follows:
GD = [(Tmáx + Tmín) /2 – Tbase], en el caso de / when Tmax Ts °C
GD = [(Taj-máx + Tmín) /2 – Tbase], en el caso de / when Tmax > Ts °C
Taj-máx = [Ts °C- (Tmáx – Ts °C)]

Where Tmax = maximum daily temperature, Tmin = minimum daily temperature,
Tbase = base temperature, Ts = upper limit temperature, and Taj-max = adjusted daily maximum temperature.

Photothermal Indices for different production regions in the world:

Photothermal Index

Napa Valley (California) 140
Valle del Maipo / Maipo Valley (Chile) 140
Valle de Colchagua / Colchagua Valley (Chile) 135
Valle de Cauquenes / Cauquenes Valley (Chile) 133
Valle del Maule / Maule Valley (Chile) 131
Valle del Limarí / Limari Valley (Chile) 127
Valle del Rapel / Rapel Valley (Chile) 123
Valle de Casablanca / Casablanca Valley (Chile) 121
Mendoza / Mendoza (Argentina) 110
Cotes du Rhône / Cotes du Rhône (France) 105
Bordeaux / Bordeaux (France) 104
Tour / Tours (France) 101
Provence / Provence (France) 90
Cape Town (Sudáfrica) / Cape Town (South Africa) 85
Toscana (Italia)/ Tuscany (Italy) 81
Adelaida / Adelaide (Australia) 80
Milán (Italia) / Milan (Italy) 58
Barrosa / Barrosa (Port Augusta, Australia) 50
Barcelona (España) / Barcelona (Spain) 31