Inviticulture, thegrape cluster (alsobunch of grapes) is afertilizedinflorescence of thegrapevine, the primary part of this plant used for food[1] (grape leaves are also used in some culinary traditions).[2] The size of the grape bunch greatly varies, from few grams to kilograms, depending on thegrape variety and conditions during thefruit set.[3]
The placement of a cluster on the vine is similar to that of atendril,[4] as both develop from the same uncommittedprimordia, theanlagen. The grape bunch position on the side of the stem opposing a leaf is unusual for inflorescence of the plants.[3] The typical shape of a cluster depends on thegrape variety.[5]
The bunch of grapes, like a tendril, has twoarms. The inner arm develops into a full-grown cluster, the smaller outer one might die off, develop into a small tendril-like arm with no fruit, or form a large "wing" with berries that sometimes ripen differently than the ones of the main cluster (for example, inTrebbiano).[3]
The grape cluster is shaped as apanicle, with the main branch ("axis") calledrachis. Additional branches ("shoulders" orbranch-twigs) are connected to the rachis irregularly and split intopedicels (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 aterminal pedicel twig). The beginning of the rachis before the first split is called apeduncle.[4][6] In a ripe cluster the peduncle might be the only fully visible part of the cluster branches.[7]
The arrangement of the branches, so calledcluster architecture, determines the distribution of berries and free space within the cluster. The architecture is complex and influences yield, quality, and resistance to pests and diseases.[8] While mostly determined by theramification patterns of the rachis, its development can be influenced by management technique, likeleaf removal.[9]
Arelational growth grammar (RGG) can be used to describe the architecture of a cluster.[10]
During the rapid growth phase of the vine shoot, futureleaf buds andfruit buds are identical. Afruit bud differentiation process occurs in a mature vine under proper climatic and growth conditions will cause some buds to develop into the fruit ones.[11] The rudiments of the future flower clusters are formed during the summer season preceding the year of flowering[12] and develop after a winter rest.[13] The flowers develop simultaneously with the leaves, starting withcalyx (about a week into theleafing phase) and followed bycorolla (another week),stamens, andpistil.[5] The flowering takes about 45 to 70 days. The small greenish flowers are usuallybisexual ("perfect").[14] The latter trait is most likely an effect of a long cultivation, the newer (mostly American) varieties have imperfect flowers with varyingintersex degrees.[15]Self-pollination is typical.[16]
Fruit set usually involvesseed development, although multiple "seedless" varieties exist where the berries contain practically no trace of seed (Black Corinth), just the embryo seeds (Thompson Seedless a.k.a. sultana), or complete, butempty seeds (Chaouch).[16]
Berry development after set includes three periods:[17]
As the berry develops, it reaches the state ofripening that depends on the future use of the fruit (the requirements might call, for example for higher acidity, or its opposite, higher sugar content). Past this stage, the berry isoverripened (typically loses the acidity, glucose content, and mechanical sturdiness).[18]
The harvesting is done by cutting the entire clusters off the vine and packing them into containers.[19] The clusters rarely reach ripeness simultaneously, so frequently two or more pickings are used, with pickers selecting the clusters based on the appearance of the berries and stems (and occasional tasting of the berries).[20]
Grape cluster might refer to very diverse notions, from unity toimmorality, it can also be a symbol of the gods of agriculture or fertility.[21]
Ancient Greek art though of clusters of grapes as symbols of fertility and sacrifice, the latter one due to blood-colored wine they produced, birds eating grapes were thought of as an expression of afterlife.[22] Personification of the grape bunch was represented byStaphylus.[23] In one myth, a goatherd namedStaphylus discovered grapes (and their sweet juice) after observing one of his master's goats getting fat and frolicsome.[24]
Like many other fruits and flowers, grape clusters are frequently used as symbols in theChristian art. Along withears of wheat they represent theEucharist, depicted alone might allude to theTrue Vine (playing the role similar to thelotus inBuddhism: "I am the vine"[25]). In the early Christianity, clusters were occasionally combined withcherubs, possibly under the influence ofBacchus worship. Two men that carry a gigantic grape cluster on a pole areMoses' spies[26] returning from thePromised Land,[27] this image is also frequently used in modern Israel to promote the tourism and wine.[28] The Bible also contains an analogy between the grape cluster and female breasts.[29][30]
Judaism used the bunch of grapes as a symbol of the nation of Israel.[31] Gary Porton (1976) suggests that the grape cluster in Judaism represents the (possiblyMessianic) "great man" and points to its use during thebar Kokhba revolt.[32][33] Menahem Mor (2016) argues that a grape cluster on the Israeli coins of theSecond Temple period depicts fertility and should be understood as a national, and not religious, symbol.[34]
Heraldry frequently does not make a distinction between a grape cluster and avinecharges,[35] theproper tincture of the fruit ispurpure,[36] the typical meaning is direct (vineyard or wine production). In military symbols, a cluster corresponds to action in a wine-producing region (like France).[citation needed]
The grape bunch is prolifically used in the decorative arts.[37]
Hellenized Jews used cluster images for mosaics at synagogues and decorations of tombs, probably alluding to the Greek symbolism of an eternal life, over time, these decorations lost their religious symbolism. As a reminder of the harvest (and thus joy), clusters of grapes are hung insukkah, and can frequently be seen onKiddush andShabbat objects.[38]