VARUN.WINE

All vines, regardless of the species they are, have a similar basic structure and have similar components. These are the three categories of components: 

(1) The Green Parts of the Vine

(2) The Woody Part of the Vine 

(3) The Roots

1. The Green Parts of the Vine                                        

The Green parts of the Vine include Shoots, Stems, Buds, Leaves, Tendrils, Flowers, Grapes, and Berries. They are the new and freshly grown parts of the vine. They are a part of the current year’s foliage and are formed and renewed every year.

1. Main Shoots grow from buds that were retained in the previous year through the process of pruning. Pruning is the process of meticulously removing branches or stems from the vine to enhance its health, increase the yield, and shape it to properly fit the vineyard’s available space. Pruning makes it possible for the desirable new shoots to grow. This new growth occurs in the springtime. The swelling or ‘‘bumps’ found at each section of the main shoot are called Nodes. The section of the stem between two consecutive nodes is called the internode.

2. The stem can be described as the ‘central nervous system’ of the Vine. It is the main portion of the vine, to which everything else is connected.   Xylem and phloem are the two types of transport tissue systems found in the stem of the Vine.  They form a complex network that helps carry resources to different parts and disposes of waste products. The primary function of xylem is to transport water and mineral nutrients from the roots to the rest of the plant (movements directed upwards), as well as to provide physical structural support. Phloem, on the other hand, transports Organic substances, including sugars generated during photosynthesis, from the leaves to other regions of the plant. Additionally, the stem is essential for storing carbohydrates, which are necessary, particularly when the plant is dormant.

3. Buds are formed between the leafstalk (called ‘petiole’) and the actual stem of the main shoot. They are also called “embryonic” shoots because, they contain the genetic codes required to produce the vine’s green components (stem, buds, tendrils, leaves, inflorescence) and the flowers that will eventually develop into berries.

Essentially, there are two types of buds:

‘Prompt’ buds and the ‘Compounds’ buds.

The “Prompt” buds break open during the growing season and form on the main shoot, creating lateral shoots.‘Lateral’ shoots are smaller and thinner than the main shoot. They are also capable of bearing flowers, which can in time turn into   berries.  The main purpose of lateral shoots is to allow the plant to continue growing if the tip of the vine has been destroyed or eaten by birds. Lateral shoots also give rise to more foliage, forming a larger canopy, greater photosynthesis and much better absorption of the sunlight and energy. However, they may potentially grow everywhere, especially near the base of the cordon. These uncontrolled growth is undesirable, especially when energy can go into the lateral shoots instead of the main shoots. Uncontrolled canopy can also impede airflow, causing mildew, and can shade the fruits. Hence, excess foliage may require removal through summer pruning, popularly known as “de-suckering”.

Compound buds or ‘latent’ buds, on the other hand, usually remain dormant until the next spring, if the grower allows it to remain during the ‘pruning’ activities.  The primary latent bud and the two accessory buds (called secondary and ‘tertiary’ buds respectively) are together called as a ‘compound bud’.  These secondary and tertiary buds are critical, especially in cold climates when the primary bud suffers from frost damage. When this happens, the secondary and tertiary buds can grow, still enabling the vine to grow a good crop.               

4. Leaves provide the largest surface area of the green part. The principal function of photosynthesis is the production of sugars. This is crucial for vine growth, metabolism and eventually for the grape sugars within the ripened grapes. ‘Stomata’ are tiny pores mainly found on the lower epidermis of the leaf, which allow gas exchange in the vine. They open up and let water diffuse out through transpiration, with carbon dioxide coming in for photosynthesis. As transpiration is in full swing, the vine draws up water from the root systems and brings it up to the leaves and the main plant. During stress due to water scarcity, the stomata will close to retain water content. However, due to this, carbon dioxide in take will be blocked, and consequently the sugar production will be stopped since photosynthesis is also blocked.

5. Tendrils can also be called the ‘’limbs’ of the vine. They are there to give structure and support to the vine. It wraps itself when it senses near a support structure like a treillage or a tree. Tendrils can break.  Therefore, the canes can be tied down by tie-wires to give the required support, especially before the formation of enough tendrils.

6. Inflorescences is the cluster of flowers (1-3 flowers usually)  depending on the grape variety. They will turn into berries eventually. A bunch of grapes is a fertilised inflorescence. Frequently, not all flowers become grapes due to factors like shedding, or inconsistent  weather. Consequently, the size and shape of the grapes can differ. There are other effects that follow from this. For example, Pinot Noir will have very tight bunches and hence more susceptibility to fungal attack, causing damaged skins and off flavours.

7. Grape has three major components, namely    stem, pulp and the seed. The stem is the grape’s stalk, holding it to the bunch.  The Pulp is the  big fleshy part, containing mainly water and also sugars such as glucose and fructose. It also contains certain Acids, Aroma compounds and aroma pre-cursors.  Aroma pre-cursors are compounds that  give wines its unique aroma characters. Grape skins contain a high concentration of aroma compounds. For this reason, the skin contact is important in the production of red wines.    Skin also contains materials  like aroma pre-cursor, tannins as well as colour imparting  compounds  like ‘anthocyanin’ . Seeds gradually mature inside the fleshy part of the grape.  Seeds have bitter oils, tannins and its embryo.  Bloom is the waxy coating on the surface of the grape. Within the bloom, there will be numerous compounds which are found in the local environment of the vineyard.  It is this aspect of the bloom that gives the wine its unique flavours and essence.   The French grape growers refer to this effect as ‘Terroir.’
8. The Woody Part of the Vine

One-Year-Old wood are the canes that grew from the buds during the previous growing season. These canes which were green shoots during summer  shall ‘lignify’(woody) and turn brown by the end of the season.  So in the following spring, buds on these canes will produce new shoots that will in turn bear fruits.

In Northern Hampshire (NH???), the vine will be trimmed in late winter or early spring to leave only the essential buds and structure for the forthcoming growing season. This ensures the vine’s energy is directed to the buds that will produce the next season’s crop, and the lignified wood will be discarded.

The volume of one-year-wood will depend on the grape grower’s pruning and training decisions. One-year-wood will support the compound buds and prompt buds. One-year-wood can become a CANE or a SPUR, depending on how it is pruned.

Canes are longer sections of prunings of the one-year-wood. Allowing the canes in the pruning process is called ‘long pruning method’.  There can be anywhere between 8-20 compounds buds on each of these canes. Canes are placed horizontally and tied to the trellis. Each compound bud on the cane will burst and form the main shoot. 

There is a “short pruning method” that allows “spurs” instead of the ‘canes’ of the “long pruning method.” The labour force doing the pruning activities needs to know what to cut and what to keep in  the vine.

Spurs are shorter sections of the one-year-wood. They are more or less a finger length. These spurs can only support around 2-3 compound buds that burst into main shoots. They are distributed along a ‘CORDON’ or at the head of the TRUNK (head trained spur in windy conditions).

The Trunk and cordons of the vine are considered permanent wood. Trunks will be more than one year, and can even be several decades old. Cordon is a longer horizontal branch at the head of the trunk and can be considered the arms of the Trunk. The trunk anchors the vine to the ground and enables the process of transpiration.  Transpiration is the process by which water and mineral solutes are moved to and from the various sections of the vine.  Furthermore, carbohydrates and nutrients are stored in the permanent wood for utilisation during the vine’s dormant phase.

3. The Roots of the Vine

Roots are all-important for the absorption and uptake of water and nutrients from the soil for photosynthesis. A network of root systems help in the anchoring of the vine. Roots also store carbohydrates below ground, just like the permanent wood does above the ground. Root systems also trigger hormones that are critical for the growth of the vine and for the ripening of the grapes. For instance, when there is a water scarcity in the soil, the roots trigger hormones that will close up the stomata on the leaves to retain the water for. 

A penetration depth of 50 cms into the soil is normal for vines. Root systems can  go even deeper,  depending on how well-fractured is the bed rock . The structure of the root system is influenced by the soil properties, irrigation, cultivation, and the types of root stocks involved.

Root stock grafting is a process where the grower unites the stem and canopy of a desirable variety of vine with the stem and roots of another hardy, cold-tolerant or pest-tolerant variety.  Rootstock grafting allows the grower to build the vine to the best possible specifications that suits the grower’s taste as well as that can adapt to the climate. 

One  typical example is the  Rootstock grafting is done in order to  protect the vine from phylloxera. Phylloxera (Daktulsphaira vitifoliae) are tiny aphid-like insects that are regarded as a grave threat to vine growing regions all over the world. Examples of root stocks that are tolerant to root knot nematodes are Dogridge, and Ramsey. Both these rootstocks are also known for its drought and salinity tolerance thereby making them very suitable for places that are prone to drought.  

Rootstock grafting is also done for the purpose of  adjusting the vines tolerance to the pH levels of the soil. For example, varieties such as    bellanderi and rupestris are suitable for acidic soils.  

Rootstocks that are hybrids of rupestris and bellanderi  will produce deep and quick rooting systems that can absorb water from the soil. 

Likewise,  the variety called, Vitis riparia is good for regions where water logging is a major challenge.  

Another example is the use of European top part (scion) as   the root stock   for the vigour of the vine.  

Similarly, in cooler regions,  low vigour root stocks can be used for advancing the ripening of the grapes.  Root stock grafting is essentially done based on the type of the root stock most desired for the soil conditions on hand.