Grape cluster

In viticulture, the grape cluster (also bunch of grapes) is a fertilized inflorescence of the grapevine, the only part of this plant used for food.^[1]

"Bunch of grapes" redirects here. For a tavern, see Bunch-of-Grapes.

Structure

Grape cluster structure

The placement of a cluster on the vine is similar to that of a tendril,^[2] its typical shape depends on the grape variety.^[3]

The grape cluster is shaped as a panicle, with the main branch ("axis") called rachis. Additional branches ("shoulders" or branch-twigs) are connected to the rachis irregularly and split into pedicels (short stems attaching individual berries). In a large cluster, the shoulders might bear secondary (sub-twigs) and sometimes tertiary branches before ending up with pedicels (the twig carrying the pedicels is also known as a terminal pedicel twig). The beginning of the rachis before the first split is called a peduncle.^[2][4] In a ripe cluster the peduncle might be the only fully visible part of the cluster branches.^[5]

A relational growth grammar (RGG) can be used to describe the "architecture" of a cluster.^[6]

Development

During the rapid growth phase of the vine shoot, future leaf buds and fruit buds are identical. A fruit bud differentiation process occurs in a mature vine under proper climatic and growth conditions will cause some buds to develop into the fruit ones.^[7] The rudiments of the future flower clusters are formed during the summer season preceding the year of flowering^[8] and develop after a winter rest.^[9] The flowers develop simultaneously with the leaves, starting with calyx (about a week into the leafing phase) and followed by corolla (another week), stamens, and pistil.^[3] The flowering takes about 45 to 70 days. The small greenish flowers are usually bisexual ("perfect").^[10] The latter trait is most likely an effect of a long cultivation, the newer (mostly American) varieties have imperfect flowers with any combination of intersexes.^[11] Self-pollination is typical.^[12]

References

1. Galet & Towey 2000, p. 88.
2. Winkler 1974, p. 118, The Cluster and Flowers.
3. Winkler 1974, p. 120.
4. Schöler & Steinhage 2015, p. 167.
5. Schöler & Steinhage 2015, p. 168.
6. Schöler & Steinhage 2015, pp. 167–168.
7. Winkler 1974, p. 112.
8. Winkler 1974, p. 118.
9. Winkler 1974, pp. 119–120.
10. Winkler 1974, p. 122.
11. Winkler 1974, p. 124.
12. Winkler 1974, p. 128.

Sources

• Galet, P.; Towey, J. (2000). "Clusters and Berries". General Viticulture. Avenir oenologie. Oenoplurimédia. ISBN 978-2-905428-13-4. Retrieved 2024-11-06.
• Schöler, Florian; Steinhage, Volker (2015). "Automated 3D reconstruction of grape cluster architecture from sensor data for efficient phenotyping". Computers and Electronics in Agriculture. 114. Elsevier BV: 163–177. doi:10.1016/j.compag.2015.04.001. ISSN 0168-1699.
• Winkler, A.J. (1974). "The Grape Flower and Berry Set". General Viticulture: Second Revised Edition. University of California Press. pp. 111–137. ISBN 978-0-520-02591-2. Retrieved 2024-11-06.