WSET Diploma D1 Exercises (The Vine Growth Cycle)

Answer

An advantageous budburst is one that is relatively uniform, leading to a crop of grapes with even ripeness. This uniformity positively impacts the wine’s flavor, balance, and overall quality.

Regions with distinct seasonal temperature variations, where temperatures rise rapidly in the spring, are advantageous for uniform budburst. In contrast, maritime climates, which exhibit less temperature contrast between winter and spring, may experience less synchronized budbursts. Additionally, a few unusually mild winter days can trigger early budbursts, which may then be harmed by subsequent cold days.

Grading Criteria

• Explanation of advantageous budburst
  • For explaining “advantageous budburst” as a relatively uniform budburst, you get 1 point.
  • For stating that a relatively uniform budburst leads to even ripeness in harvested grapes, you get 1 point.
  • For stating that even ripeness in harvested grapes positively impacts the wine’s flavor, balance, and quality, you get 1 point.
• Ideal condition
  • For explaining that the ideal condition involves distinct seasonal temperature variations, you get 1 point.
  • For explaining that in the above ideal condition, rapidly rising temperatures in the spring lead to a uniform budburst, you get 1 point.
• Non-ideal condition
  • For stating that non-ideal conditions include maritime climates, which show less temperature contrast between winter and spring, you get 1 point.
  • For explaining that less temperature contrast between winter and spring results in unsynchronized budburst, you get 1 point.
  • For stating that the non-ideal condition involves a few unusually mild winter days, you get 1 point.
  • For explaining that a few unusually mild winter days can lead to earlier budburst, you get 1 point.
  • For explaining that earlier budburst can be damaged by subsequent cold days, you get 1 point.

Answer

Coulure is a condition in grape bunches where a high proportion of flowers fail to develop into fruit due to unsuccessful ovule fertilization. While some degree of coulure is normal, excessive occurrence can dramatically reduce the overall yield of a vineyard.

The causes of coulure are primarily related to an imbalance in carbohydrate levels within the vine. This imbalance is often caused by low photosynthesis rates. In cold, cloudy conditions, leaves cannot access the necessary sunlight for photosynthesis. Also in hot, arid conditions with high water stress, the vine halts photosynthesis to conserve water.

This imbalance can also result from vigorous shoot growth, which diverts carbohydrates away from the inflorescences. Very fertile soils, heavy application of fertilizers, and vigorous rootstocks can all lead to strong shoot growth, further exacerbating coulure.

Grading Criteria

• About Coulure
  • For the statement that coulure is a condition where a high proportion of flowers fail to develop into fruit, you get 1 point.
  • For the pointing out that coulure is caused by unsuccessful ovule fertilization, you get 1 points.
  • For the statement that excessive coulure can dramatically reduce the overall yield of a vineyard, you get 1 point.
• Causes
  • For the statement that the primary reason for coulure is an imbalance in carbohydrate levels, you get 1 point.
  • For listing low photosynthesis rates and vigorous shoot growth as reasons for the aforementioned imbalance, you get 1 point each, for a total of 2 points.
  • For identifying cold, cloudy conditions and arid conditions with high water stress as causes of low photosynthesis rates, you get 1 point each, for a total of 2 points.
  • For identifying very fertile soils, heavy application of fertilizers, and vigorous rootstocks as causes of vigorous shoot growth, you get 1 point each, with a maximum of 2 points.

Answer

During the early grape growth stage, following fruit set, grapes grow in size and accumulate tartaric and malic acids that influence the wine’s flavor. Additionally, some aroma compounds and precursors such as methoxypyrazines develop, enhancing the wine’s aromatic profile. At this time, tannins also accumulate, with sunshine further promoting this process.

High water flow, mainly transported by the xylem, supports these developments. However, excessive water can delay ripening by promoting shoot growth over grape maturation, potentially leading to underripe grapes if not managed correctly. On the other hand, mild water stress can hasten ripening, producing smaller grapes with a higher skin to pulp ratio, enhancing color, tannins, and aroma compounds in red wines.

Grading Criteria

• Change in grapes
  • For identifying each of the four changes, you get 1 point, for a total of 4 points.
    • Grow in size.
    • Accumulate tartaric and malic acids.
    • Some aroma compounds and precursors develop.
    • Accumulate tannins.
  • For the listing some examples of aroma compounds and aroma precursors that accumulate in this stage, such as methoxypyrazine, you get 1 point.
  • For the pointing out that sunshine promotes tannin accumulation, you get 1point.
• Water affect
  • For the statement that high water flow supports these developments, you get 1 point.
  • For the pointing out that water is mainly transported to the grape by the xylem, you get 1 point.
  • For the statement that excessive water can delay ripening, you get 1 point.
  • For the reason delaying rippening, that excessive water promotes shoot growth rather than rippening, you get 1 point.
  • For the statement that excessive water leads to underripe grapes if not managed correctly, you get 1 point.
  • For the statementt that mild water stress can hasten ripening, you get 1 point.
  • For the statement that hastened ripening leads to smaller grapes with a higher skin to pulp ratio, you get 1 point.
  • For the statement that smaller grapes enhance color, tannins, and aroma compounds in red wines, you get 1 point.

Answer

Ideal conditions for suger accumulation in the ripening stage are warm (temperatures between 18–33°C), dry, and with sufficient sunlight levels above one third of full sunshine.

In cold weather or under constant cloud cover, the rate of photosynthesis decreases. Similarly, extremely hot and dry conditions can lead to severe water stress, potentially causing photosynthesis to slow or even cease. Both scenarios result in inadequate photosynthesis, which leads to reduced sugar accumulation in the grapes.

In cool or humid conditions, the rate of grape transpiration slows down. This slows the movement of the sugary solution from the phloem into the grape, leading to low sugar accumulation. Conversely, in warm conditions, sugar accumulation can be too rapid, reaching high levels before aromas, flavors, and tannins have fully developed.

Grading Criteria

• For the statement that the rate of photosynthesis decreases in cold weather or under constant cloud cover, you get 1 point each, for a total of 2 points.
• For the statement that photosynthesis slows or even ceases in extremely hot and dry conditions, you get 1 point.
• For the explanation that the reason is due to water stress under high temperature and dry climatic conditions, you get 1 point.
• For the conclusion all of above condition leads to reduced sugar accumulation in the grapes due to insufficient photosynthesis, you get 1 point.
• For the statement that the rate of grape transpiration slows down in cool condition, you get 1 point.
• For the statement that these slows the movement of the sugary solution from the phloem into the grape, you get 1 point.
• For the conclusion that this cool condition leads to low sugar accumulation, you get 1 point.
• For the statement that sugar accumulation can be too rapid in warm condition, you get 1 point.
• For pointing out its level is so rapid that sugar reaches high levels before aromas, flavors, and tannins have fully developed, you get 1 point.

Answer

Malic acid can be metabolized during respiration in the ripening stage. Therefore, in cool conditions, grape respiration slows down, resulting in higher levels of retained malic acid.

Tartaric acid in the grape generally does not change in climate condition.

Grading Criteria

• Malic acid
  • For the conclusion that cool conditions result in high levels of retained malic acid, you get 1 point.
  • For the explanation that this is because grape respiration slows down, you get 1 point.
  • For the premise that malic acid is metabolized during respiration, you get 1 point.
• Tartaric acid
  • For the conclusion that cool conditions do not affect the level of tartaric acid, you get 1 point.

Answer

Grape variety, climatic conditions, management of the vine and vineyard and time of harvest are impact the length of the ripening stage.

Different grape varieties have inherent genetic predispositions affecting their ripening times. For example, Chardonnay and Pinot Noir typically ripen earlier, whereas Cabernet Sauvignon and Grenache usually ripen later. Varieties like Zinfandel are known for their uneven ripening.

Warm, dry conditions generally accelerate sugar accumulation, which accelerate ripening stage. Extreme heat or drought can halt vine activity and slow down the process.

High yields and excessive shading within the vine canopy, for instance, can slow down the ripening process.

The timing of harvest can be adjusted based on the wine producer’s desired style of wine or weather.

Grading Criteria

• For identifying each of the four factors that impact the length of the ripening stage, you get 1 point, for a total of 4 points:
  • Grape variety
  • Climatic conditions
  • Management of the vine and vineyard
  • Time of harvest
• Grape variety
  • For listing examples of early ripening varieties such as Pinot Noir and Chardonnay, you get 1 point.
  • For listing examples of late ripening varieties such as Cabernet Sauvignon and Grenache, you get 1 point.
  • For listing examples of varieties prone to uneven ripening such as Zinfandel, you get 1 point.
• Climatic conditions
  • For the statement that warm, dry conditions accelerate sugar accumulation, you get 1 point.
  • For the conclusion that these conditions accelerate the ripening stage, you get 1 point.
  • For the statement that extreme heat or drought can halt vine activity, you get 1 point.
  • For the conclusion that these conditions slow down the ripening stage, you get 1 point.
• Management of the vine and vineyard
  • For the statement that management of the vine and vineyard can slow down the ripening process, you get 1 point.
  • For listing examples of vine and vineyard management such as high yields and excessive shading within the vine canopy, you get 1 point.
• Timing of harvesting
  • For pointing out that the timing of harvest can be adjusted based on the wine producer’s desired style of wine, you get 1 point.
  • For pointing out that the timing of harvest can be adjusted based on weather, you get 1 point.

Answer

Tannins accumulate during the pre-véraison stage, imparting a bitter taste to the grapes. The levels of tannins peak at véraison and then slightly decrease throughout the ripening process. During this stage, the tannins undergo polymerization, which softens their bitter taste.

Sunshine on the grapes promotes tannin accumulation pre-véraison and enhances polymerization post-véraison. This leads to a more bitter taste pre-véraison and a less bitter taste post-véraison.

Grading Criteria

• For the statement that tannins accumulate during the pre-véraison stage, you get 1 point.
• For the explanation that this imparts a bitter taste to the grapes, you get 1 point.
• For the statement that the levels of tannins peak at véraison, you get 1 point.
• For the statement that tannins slightly decrease throughout the ripening process, you get 1 point.
• For the statement that tannins undergo polymerization throughout the ripening process, you get 1 point.
• For the explanation that this softens their bitter taste, you get 1 point.
• For the statement that sunshine promotes tannin accumulation pre-véraison, you get 1 point.
• For the explanation that this leads to a more bitter taste, you get 1 point.
• For the statement that sunshine enhances polymerization post-véraison, you get 1 point.
• For the explanation that this leads to a less bitter taste, you get 1 point.