Definition: ampelographer

The ampelography of grape varieties
Ampelography is the study of the foliage, bunches, shoots, bud break, flowering, veraison, ripeness, leaf fall, production, etc. of different grape varieties. The word ampelography comes from two Greek words, "ampelos", meaning vine, and "graphein", meaning to write. Ampelography is useful for understanding the characteristics specific to each grape variety. Studies have even gone so far as to define a variety's vulnerability to pests and various diseases, categorise its organs, etc. It is very important to understand the benefits of ampelography in order to identify grape varieties within vineyards.

Understanding ampelography
Ampelography has been around since 1951 and we already have more than 5,000 different grape varieties. The OIV, the International Organisation of Vine and Wine, has identified 88 descriptors for these different organs. The morphology and varieties of vines are of paramount importance in influencing plant material and product production. In addition to this relevant information, grape varieties are geographically classified. This classification is called a cadastre, and enables production and marketing.

Ampelometric measurements are quantitative measurements taken on dried, healthy adult herbarium leaves. The details include the depth of the sinuses, the shape of the teeth, and the angle and length of the veins. It is best to observe the adult leaf in July, the bunches and berries in September, and finally the shoots in winter.

Ampelographic standards
The morphological descriptors of ampelography are identified by a standardised code developed by the OIV. For each organ, we give points by category in a table:

Categories: budding, young leaf, shoot, cluster, berry, etc.

* Character
* Hairiness
* Colour
* Shape and size
* Texture, appearance, consistency and flavour

Key points to remember about ampelography
Ampelography is an important factor in the enforcement of laws and the protection of licences and patents. Ultimately, in order to establish a good quality grape variety, an ampelographic study of colour, acidity, yield, sugar content, earliness, aroma and resistance to pests and various diseases is required.

DNA to the rescue of ampelography
Molecular biology provides additional information. While ampelographers study the external appearance, molecular biologists observe what is inside the plant: its DNA. DNA encodes all of the organism's genetic information using its components, nucleic acids. The analysis involves taking DNA samples from very young leaves, one to two centimetres long.
Each variety, or grape variety, has a molecular identity card. It is a kind of fingerprint. A process called electrophoresis reveals this unique genetic code: DNA fragments are selected by immersing them in an agarose gel and subjecting them to an electric current that causes them to migrate. As with soil in a sieve, DNA separation is based on size. The larger the DNA fragment, the less it moves through the gel; the smaller it is, the further it travels. However, nothing can be seen with the naked eye. After staining, ultraviolet light reveals the position of the DNA fragments in the gel, where they are spaced according to their length, creating a kind of bar code.