Quiz - Natural factors in the vineyard Flashcards
What are the four most important native North American vine species used in viticulture?
- Vitis berlandieri
- Vitis labrusca
- Vitis riparia
- Vitis rupestris
What are the names for the two methods of vine propagation that produce vines that are genetically identical to the parent vine?
Cuttings and layerings
The pulp of most grapes is colorless. However, some grapes have red-colored pulp.
What is the term used for a grape with red pulp?
Teinturier
What are the two ways how new grape varieties can be created?
Crossing:
When the two parent vines used to create a new grape variety are from the same species.
Hybrid:
When the two parent vines used to create a new grape variety are from different species.
Briefly describe the processes of Clonal and Mass selection.
What are the advantages/disadvantages of either approach?
Clonal selection is the process of taking a cutting from a single parent plant and propagating vegetatively over time to create a new plant that is genetically identical to the parent.
Advantages:
* Management of the vineyard may be easier if the vines ripen at a similar time.
* Clonal selection is generally done in nurseries and checks vines for viruses, so vines are virus free.
Disadvantages:
* Reduces diversity in the vineyard and in the fruit which may produce wines that are less complex.
* The same plant in one area could lead to high disease pressure as there may be no or little resistance to certain diseases or pests.
Mass selection is carried out by taking cuttings from certain vines that display desired characteristics which can include high quality fruit, high disease resistance, etc. This process takes many years as monitoring of how the vine grows and the wines produced from the grapes are assessed until the vines produce what the grower is looking for.
Advantages:
* It increases diversity in the vineyard and potential wines due to the plants coming from the growers’ own vineyard.
Disadvantages:
* Costly and time consuming to produce a new plant.
* The new plant is not guaranteed virus free.
Name some popular hybrids or crossings.
Hybrid:
* Vidal
Crossing:
* Müller-Thurgau
* Pinotage
What are the key things the vine needs at different stages of growth?
- Dormancy: Temperatures below 10°C
- Budburst: Temperatures above 10°C
- Shoot and Leaf Growth: Stored carbohydrates
- Flowering and Fruit Set: Temperatures above 17°C
- Grape Development: Mild water stress
Which main events take place in a vine’s growth cycle throughout the seasons?
Winter - Dormancy
Spring - Budburst
Early Summer - Flowering, pollination & fertilization
Late Summer - Grape development
During the growing season, vines produce and store carbohydrates.
Which carbohydrate is primarily used to support a vine’s growth during dormancy?
Starch
From March–July in the Northern Hemisphere and September–January in the Southern Hemisphere, carbohydrates stored in the roots, trunk and branches support initial shoot growth of the vine. However, if levels of carbohydrate are low, shoot growth can be negatively affected. Briefly describe what factors may cause carbohydrate levels to be lower than required and what impact these issues might cause.
Carbohydrates levels can be low in the vine due to the previous year’s cultural manipulations including excessive leaf removal. Leaves are a source of carbohydrates, therefore this canopy management technique needs to be clearly understood by the grower before being carried out so as not to unnecessarily deplete the vine.
Cropping the vine very heavily can use up some of the carbohydrates stored in the trunk and roots leaving less available in the following growing season and weakening the vine in the longer term.
Water stress has a major impact on photosynthesis, a lack of water will result in the stomata closing to preserve the water in the vine. This will affect carbon dioxide not being able to enter the plant and stopping or reducing photosynthesis. As a consequence, the amount of carbohydrates will be reduced and thus depleting the store.
High levels of disease that affect the green parts of the plant e.g. downy and powdery mildew attack the leaves. This will reduce the level of photosynthesis, thus reducing the store of carbohydrates available to the vine.
Which temperature range is required for successful pollen germination?
26–32°C / 79–90°F
Briefly describe the process of vine pollination. Be sure to include details on the anatomy of a vine flower, and how the plant develops grapes once fertilized.
- An inflorescence contains individual flowers, when these open it is described as flowering.
- Each flower contains pollen-laden stamens (anther and filament) which become exposed during flowering.
- Pollen will disperse and land on the receptive stigma surface, this is referred to as pollination.
- If germination is successful (pollen grains germinate and produce pollen tubes), pollen tubes grow.
- Pollen tubes penetrate the stigma and the ovule in the ovary, delivering the sperm cells which fertilize the eggs in the ovule.
- Formation of the berry occurs, the fertilized ovules form the seeds and the wall of the ovary swells, forming the skin and pulp of the berry.
Coulure and Millerandage are two common forms of irregular fruit set.
Describe coulure and millerandage.
Coulure - A condition of the grape bunch in which fruit set has failed for a high proportion of flowers.
Millerandage - A condition of the grape bunch in which there is a high proportion of seedless grapes.
What is the name of the type of aroma compound that develops during early grape growth and often contributes toward herbaceous flavors and aromas?
Methoxypyrazines
What is the name of the tissue that transports water and some nutrients from the roots to the grapes and other parts of the vine?
Xylem
