MONDAY IN THE VINEYARD SERIES
From Twisted Tendrils to Leafy Labyrinths: Unraveling the Playful Puzzle of Vine Canopy!
Vines share a common framework, which can be categorized into four parts: canopy, one-year-old-wood, permanent wood, and roots. The canopy encompasses the shoots and their key components like buds, leaves, lateral branches, tendrils, and grape clusters, forming a vibrant ensemble.
1. The Fascinating Anatomy of Vines: Shoots
Vine shoots sprout in spring, emerging from buds held over from the previous year. These shoots encompass vital elements such as buds, leaves, tendrils, lateral branches, and grape clusters. Acting as conduits, the shoot's primary axis transports water and solutes (including sugars and minerals) and serves as a carbohydrate reservoir. Nodes, small bulges along the shoot, serve as attachment points for other structures, while the spaces between nodes are referred to as internodes. As summer draws to a close, leaves descend, and the green shoots mature, transforming into rigid, brown canes. This process is known as lignification.
2. The Fascinating Anatomy of Vines: Buds
Buds develop between the leaf stalk and the stem, containing miniature versions of various vine components such as the stem, tendrils, leaves, and inflorescences. Two main types of buds exist:
Compound buds: emerge in one season and open in the following season. They consist of a primary bud as the main growth point, along with smaller secondary and tertiary buds that grow if the primary bud is damaged.
Prompt buds: form and open within the same season. Prompt buds emerge on the primary shoot and give rise to lateral shoots.
3. The Fascinating Anatomy of Vines: Lateral Shoots
Lateral shoots, growing from prompt buds, emerge in the current year and are smaller and thinner than primary shoots. They consist of stems, leaves, buds, tendrils, and sometimes inflorescences. Their primary role is to sustain growth if the tip of the primary shoot is damaged.
+ Lateral shoots benefit from sunlight when located near the ends of primary shoots and contribute to photosynthesis.
- However, if closer to the base, lateral shoots obstruct airflow and create excessive shade for the fruit.
These shoots can be removed through summer pruning.
SECOND CROP
Lateral shoots often produce inflorescences, referred to as a "second crop", which varies depending on grape variety and canopy management techniques. The second crop shows a delayed ripening compared to the grapes on the main stem. If harvested together with the main crop, the second crop may have higher acidity, lower sugar content, underripe tannins, and less color development in black grapes. There are two main ways of handling the second crop:
Green harvesting: it removes the second crop during the growing season, enhancing the ripening and uniformity of the remaining bunches.
Selective hand-harvesting: Main and second crops are hand-harvested at different times, whenever each of them reached the optimum ripeness level. Machine harvesting is unsuitable as it can't avoid collecting all the grapes at the same time.
4. The Fascinating Anatomy of Vines: Tendrils
Vines require support since the shoot is unable to stand independently. In natural settings, tendrils serve the purpose of attaching the vine to other plants or trees for support. In viticulture, grape growers utilize trellises to position the vine canopy. Tendrils wrap around trellis wires to secure the canopy, but growers often supplement this by tying in canes and shoots to ensure stability. Trusting the tendrils alone to hold the vine to the trellis is not common practice among grape growers.
5. The Fascinating Anatomy of Vines: Leaves
Leaves serve as the primary site for vine photosynthesis, producing sugars essential for growth and metabolism.
Stomata, found on the underside of leaves, facilitate the exchange of water and carbon dioxide. Water diffuses out through stomata, a process known as transpiration, drawing nutrients from the soil to the leaves.
If the vine experiences water stress, the stomata partially close to conserve water but restrict the entry of carbon dioxide, consequently limiting photosynthesis.
6. The Fascinating Anatomy of Vines: Inflorescences
Inflorescence refers to a flower cluster on a stem, transforming into a grape bunch during fruit set. The quantity of inflorescences per shoot varies, typically ranging from one to three, depending on the grape variety.
7. The Fascinating Anatomy of Vines: Bunches
A bunch of grapes results from a fertilized inflorescence, but not all flowers in the inflorescence develop into grapes. The properties of the grapes and the size and shape of the bunch differ among grape varieties and even within clones of the same variety. Certain grape varieties, like Pinot Noir, can have tightly packed bunches, increasing the risk of fungal diseases due to grape-skin splitting during growth and limited airflow through the bunch.
If you want to know more about Vine's Anatomy, stay tuned. Next Monday we will look at Grapes.
Happy week and happy learning!
Nicky