The cultivated grapevine is mostly monoecious (monocean) with hermaphrodite, that means bisexual flowers. It is self-pollinating, but can also be cross-pollinated. The Wild vines are mostly dioecious (diocese), that means there are plants with exclusively male or exclusively female blossoms, so that a so-called selfing (Self-fertilization) is excluded. In single-plant plants, both sexes occur on one plant. The flowers can be separate sexes, so that male and female flowers occur on the same plant, but in separate inflorescences, or they are hermaphroditic Hermaphrodite flowers in which male and female sexual organs are united in one flower. The vine is a covered plant. That is, the flower bud is covered with the perianthium, which in the time of the blossom is opened or discarded in order to enable pollination (and subsequent fertilization). As a rule, the cultivated grape varieties are bisexual. But there are also single-sex (female) varieties with exclusively female Floral organs.
There are three ways in which the sexual organs are arranged in plants. In the first option, the "genitals" are separated on two different plants, for example a tree with only functional male parts (and stunted female parts) and a second tree with only functional female parts (and stunted male parts). Now the two have to "come together". The plants rely on outside help, that is, on wind and insects. Many flowers are therefore not fertilized and the fruit yield can be relatively low. Incidentally, such plants are called “dioecious”, because the male and female sexual organs are each so to speak on their own “house” (plant). As already mentioned above, this form usually occurs in most grape vines.
The second option is plants, where the genitals are separate but are present on the same plant. This means that there is a male part on branch A and a female part on branch B. Coming together is easier there, but still difficult, since the plant also relies on outside help. Such plants are called "one-house" because both sexual organs are in one "house". The third option is hermaphrodite flowers (hermaphrodites), where the male part (seed = pollen) and the female part (scar) are combined in one organ. This is usually the case with the cultivated vine. Here the plant is not or hardly dependent on outside help. At the time of flowering, the male pollen bag opens, the pollen is released and caught by the sticky female scar underneath. The prerequisite, however, is that it is not self-sterile, which is often the case with uncultivated plants. It protects itself, so to speak, against (mostly negative) inbreeding; just one pollination leads to positive Heterosis effects,
Takes place during the blossom fertilization by pollen from the same vine on one (autogamy) or between two flowers (geitonogamy) is called self-fertilization or selfing, If two different vines are involved (no matter whether the same or a different variety) one speaks of pollination (Xenogamie). For the fruit set and the berry development it is largely irrelevant whether the seed itself or was cross-pollinated. However, the cultivated vines are usually not self-sterile. For the most part, self-fertilization takes place within the hermaphrodite flower. The problem-free self-fertilization is somewhat different for each variety. Lack of ability to do this, among other things Greenfinch (Noble Franconian) and some Traminer clones, Such varieties are often parthenokarpisch (virgin) and thus seedless (without seeds). You need pollen donors that used to be mixed in old vineyards. They cause problems in single-variety plants, especially when the blooming weather is bad, when the pollen does not fly far enough and is washed out of the air by the rain. One example of a good self-pollinator even in wet weather is the Riesling,
It is only through fertilization that each individual emerges blossom a single berry. If there is no fertilization, then there is no berry, with such flowers it comes to Verrieseln, In a fertilized berry, up to five (rarely six) embryos = kernels are potentially ready for a new variety. This means that all genes of the two parents have been passed on there. If it was self-fertilization, this is for example Grüner Veltliner x Grüner Veltliner. But if the pollen has come from the neighboring garden, where there is a Pinot Noir, then the Grüner Veltliner x Pinot Noir (the mother is always mentioned first). This natural crossing result But as I said, it is only potentially (slumbering) and is not used in viticulture. The grapes correspond externally and from the varietal Properties always 100% of the mother, regardless of the paternal genes in the grape seeds.
Only when such a grape seed of a grape gets into the ground, begins to germinate there, to one seedling (young vine) grows, it then blooms, fertilization takes place and finally grapes form, only then is this grape seed the now realized result of a previously only potentially available possibility. A new grape variety with possibly new properties is created when fertilization has been carried out by a different vine from another grape variety. In this way, the approximately 8,000 to 10,000 grape varieties were formed through spontaneous or natural crossings over many thousands of years. In principle, the genes are mixed again even if there are two vines of the same variety, but the genetic differences are then small.
At a new breed nature is imitated, so to speak. You castrate them mother places by removing the male part of the flower to prevent self-fertilization. Then you take pollen from the desired father variety and put it on the scar of the mother. The seeds are removed from the full-grown berry, placed in the ground and a new vine is grown. You do this with a few hundred berries and select more and more depending on the desired properties until the best or most appropriate results remain. A complete list of keywords relevant to grape varieties can be found at grapevine contain.
Graphics: taken from Bauer / Regner / Schildberger, viticulture,
ISBN: 978-3-70402284-4 Cadmos Verlag GmbH