The cultivated grapevine is mostly einhäusig (monoecious) with zwittrigen, that is two-sexed flowers. It is self-pollinated, but can also be cross-pollinated Wild vines are mostly dioecious, that is, there are plants with exclusively male or exclusively female blossoms, so that thereby a so-called selfing (Self-fertilization) is excluded. In monoecious plants, both sexes occur on a plant. The flowers may be of different sexes, so that male and female flowers are, or are, on the same plant but in separate inflorescences hermaphroditic Hermaphrodite flowers in which male and female sexual organs are united in one flower. The vine is a bedecktsamige plant. That is, the flower bud is covered with perianth (perianthum), which in the period of blossom is opened or dropped, thereby enabling a pollination (and immediately following fertilization). As a rule, the cultivated grape varieties are two-sexed. But there are also unisexual (female) varieties exclusively female Floral organs.
There are three ways in which the sexual organs are arranged in plants. In the first possibility, 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). Now the two have to "come together". The plants are dependent 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, so to speak, each on their own "house" (plant). This form occurs in the grapevines as already mentioned above usually in most wild vines.
The second possibility is plants, where the genitals are separated but present on the same plant. That is, on branch A there is a male part, and on branch B there is a female part. It's easier to get together, but it's still difficult, as the plant relies on outside help as well. Such plants are called "einhäusig" because both sexual organs are on a "house". The third possibility is hermaphrodites, where the male part (seed = pollen) and the female part (scar) are united in one organ. This is usually the case with the cultivated grapevine. Here the plant is not or hardly dependent on external help. At the time of flowering, the male pollen sack opens, the pollen is released and caught by the underlying sticky female scar. The prerequisite is that it is not self-sterile, which is often the case with uncultivated plants. She thus protects herself from a (mostly negative) inbreeding; just one pollination leads to positive Heterosis effects,
Done during the blossom Fertilization by pollination of the same vines on one (autogamy) or between two flowers (geitonogamy), one speaks of self - fertilization or selfing, If two different vines are involved (no matter whether same or foreign variety) one speaks of pollination (Xenogamie). For the fruit set and berry development, it is largely irrelevant whether the seed itself or was externally pollinated. The cultivated vines are usually not self-sterile. For the most part, self-fertilization takes place within the hermaphrodite. The problem-free self-fertilization is somewhat different per variety. Lack of ability to do so Greenfinch (Adelfränkisch) and some Traminer clones, Such varieties are then often parthenokarpisch (juvenile) and with it seedless (without seeds). You need pollen donors, who used to stand in the mixing set in old vineyards all around. In unmixed plants, they cause problems, especially in bad blooming weather, when the pollen does not fly far enough and are washed out of the air by the rain. A good pollinator even in wet weather is for example the Riesling,
Only through the fertilization arises from each individual 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, the up to five (rarely six) embryos = nuclei are potentially ready for each new variety. That is, all the genes of the two parents have been passed on there. Was it a self-fertilization, then this is, for example, Grüner Veltliner x Grüner Veltliner. But if the pollens have come from the neighboring garden where there is a Pinot Noir, then Grüner Veltliner x Blauburgunder (the mother is always named first). This natural crossing result but as I said only potentially (dormant) available and does not apply in viticulture. The grapes correspond externally and from the varietal Properties always to 100% of the mother, regardless of the paternal genes in the grape seeds.
Only then, if such a grape seed of a grape berry gets into the soil, there begins to germinate, to a seedling (young vine) grows, then it comes to flowering, a fertilization takes place and finally grapes form, only then is this grape seed the now realized result of a hitherto only potentially available possibility. A new grape variety with possibly new properties arises when the fertilization was done by a foreign vine of another grape variety. In this way, in many thousands of years, the currently about 8,000 to 10,000 grape varieties were formed by spontaneous or natural crosses. In principle, the genes are also remixed when it comes to two vines of the same variety, but the genetic differences are then low.
At a new breed is, so to speak, imitated nature. They castrate the mother places by removing the male flower part to prevent self-fertilization. Then you take pollen from the desired parent and bring it to the scar of the mother. The mature berry is removed from the kernels, put them in the ground and pulls up a new vine. This is done with a few hundred berries and selects depending on the desired properties more and more, until the best or most accurate results remain. A complete list of grapevine relevant keywords is under grapevine contain.
Graphics: Taken from Bauer / Regner / Schildberger, viticulture,
ISBN: 978-3-70402284-4 Cadmos Verlag GmbH