The Influence of Climate and Soil Characteristics on Fruit Quality of Wine Grapes in New Zealand
by So Pyay Thar
Wine is one of the eldest beverages consumed throughout the world today (McGovern, et.al., 2000). It has been widely consumed for many years for its attractive aroma, exceptional taste as well as for social, recreational, ceremonial, medicinal and dietary purposes, etc. (Estreicher, 2004). Producing high quality grape wine has always been a challenge for many wine industries around the world. However, most of the winemakers agree that high-quality wine begins with the land and the natural environment of the region in which the grapes are grown (Goldammer, 2013).
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Figure 1. Conceptual model to show how soil, climate and vineyard management can affect the fruit composition directly or indirectly through canopy microclimate and vine physiology (Source: Smart et al, 1985; Weldon, 2003; Sluys, 2006)
The rest of the review is organized as follows; the next section describes the influence of climate on grape wine quality followed by detailed impacts of temperature, solar radiation, rainfall, wind and frost. Next the influence of soil characteristic including soil structure, soil texture, soil type, soil depth and soil pH are described and concluded with the discussion of the New Zealand wine industry.
Influence of Climate on Grape Wine Quality
The effect of climate on Agriculture is especially evident with the cultivation of grapevines (Jones, 2005). Likewise, Jackson (2001) stated that the grape vine is “one of the most responsive cultivated plants to the ever changing surrounding climatic conditions”.
The climate is affected by the altitude and latitude which in turns affect the ripening of the fruit. Between the latitudes of 30° to 50°, having a mean annual temperatures of 10°C and 20°C, grape cultivation occurs mainly (Jackson, 2001). Hence, most of the worlds’ wine producing regions are located between 30° and 50° latitude in both north and southern hemispheres (Neirynck, 2009). Berry (1990) stated that outside these latitudes there is either the problem of excessive heat or severe cold. The intensive heat can prevent the vine from a dormant resting stage and lead to burning of grapes and leaves reducing in quality by eliminating the aroma and color in the wine. On the other hand, severe chills can prevent the grapes from taking up sufficient sugar for full ripeness causing tart and over acidic wines. Therefore, it can be stated as a general rule that grapes can be grown for wine-making anywhere between 30° and 50°. According to Thropy (1971), New Zealand lies between 34° and 47°. The Bordeaux district, the home of the famous French clarets, lies approximately in the same latitude as Timaru (44°) in New Zealand. So, in general, New Zealand lies in the temperate zone.
There are many individual weather and climate factors that have a profound impact on the fruit maturity, grape growth and wine quality such as temperature, solar radiation, rainfall, wind, and frost (Zoecklein, 2010). As several classifications of climate exist for vine compatibility, wine growers have been concerned about climate for a longtime. There have also been various studies in which the weather and climate influence the quality of grapes to produce high quality wines (Fitzharris et. al, 1996; Ubalde et.al, 2010; Lorenzo, et. al., 2013). Due to these major influences, grapes possess the ability to ripen to optimum levels of sugar, acid and flavor maximizing the quality of wine grapes (Jones, 2005). Therefore, climate influences the rate of change in the grape during development and its composition at maturity.