Overview of Grapevine Structure and Function

Grapevine is an interesting plant not only that it produce some of the best fruit on earth which can be transformed into the wine, but also as the plant itself. Grapevine is a permanent plant but differs from other permanent plants in many ways. So, in order to successfully maintain vine and produce the best possible grapes and thus the wine, it’s important to know each and every grapevine parts and it’s functions.

Grapevine is a climber which naturally grows on the trees and bushes, high and in wide shapes. In the vineyard its growth is maintained with the pruning in order to control the quantity and quality of the grapes.

Like any other plant also grapevine has its underground and above-ground part. The underground part consists of an underground trunk with the root system. While the above ground part consists of the trunk, canes, and shoots. On the one-year-old shoots, there are leaves, tendrils, flowers, and grapes.

Root system

The roots of a grapevine are multi-branched structures that grow to various depths into the soil depending on the variety (rootstock), soil and climate. Some varieties develop very deep and almost vertical roots while others have very flat and shallow roots system and therefore requires deep, fertile soil.

Read also: Structure and function of grapevine root system

Trunk

is the main steam, it’s permanent and supports the above-ground vegetative (leaves and stems) and reproductive (flowers and fruits) structure of the vine. The height of the trunk and also its branched varies with the selected training system. In cane-pruned training system, the top of the trunk is called the head. Fully developed trunk has arms – short branches from wich canes and spurs originate. Depending on a selected training system arms are located in different positions. In training system that utilize canes (cane-pruned training system) – one-year-old wood arise from arms usually near the head of the vines. While in training system that utilizes cordons (cordon training with spur pruning) arms are spaced at regular intervals along their length. *Cordons are extensions of the trunk that usually grows horizontally along a trellis wire.

Canes

When the shoots mature and woody, it becomes a vine cane. Canes if therefore one year old, woody and, matured shoot; after the leaves has fallen off. Canes are the main concerns for winegrowers during the dormant season. With the winter pruning of canes, winegrowers are managing vine size and shape and therefore control the quality of crop in the coming season.

Buds

develop in the leaf axil, right above the connection between the shoot and leave petiole. Inside each bud, there are three distinct growing points, each capable of producing a shoot, also known as primary, secondary and tertiary buds. Bud is actually a highly compressed shoot with all its parts, including cluster. At bud burst normally primary bud begins to grow, but sometimes also secondary or tertiary buds, so there can be two or three shoots on the same axil. In case the primary bud is damaged or freezes, then the secondary or tertiary buds grow in place of the primary bud. In comparison to the primary bud secondary and tertiary buds generally, have little to no fruit.

Shoots

are green stems which develop from buds, and represent the primary growth structure of grapevines. The shoots that arise from primary (winter) buds are normally the fruit-producing shoots. The shoot consists of stems, leaves, tendrils and fruits. *Canopy is a collective term that is used to describe the shoots, leaves, and fruits of the grapevine.

Leaves

The leaves of the grapevine, as any other plant, provide nourishment and air for the plant. Leaves are converting sunlight into usable energy for the plant. More leaves are well sunlit more organic compounds the grapevine can use for its growth. The shape and size of leaves are determined by the grapevine variety, as well as color, which varies from light to dark green.

Tendrils

are a slender structure that appears on the top and sides of stems. They grow until the grapevine is ready for harvest, after the harvest they become wooden in nature. Since the grapevine is a climber it needs tendrils to coil around small objects such as fences, trellises, etc. to reach up for the sun and heat. Tendril and flower cluster have a common development origin, therefore, we might find flowers design developed at the end of the tendril.

Flowers and Grapes

Flower cluster grow on the opposite site then leaves along the shoot. Most fruitful shoots develop from one to three flower clusters depending on the variety and growing conditions. Each cluster may contain only a few or up to several hundred flowers at the time of bloom; the number depends on the variety and environmental conditions. When fertilized, the flower clusters develop into clusters of grapes – the fruit set – and the berries start to grow.

Sources:
Grapevine Structure and Function, by Edward W. Hellman
Grapevine Structure and Function, in Grape Grower’s Handbook, by Ted Goldammer
Lexicon of grapevine
Photo source: Dave Johnson for Bay Area News Group