In botany, parthenocarpy is the formation of a fruit not preceded by fertilization of the ovules contained in the ovary. For this reason the parthenocarpic fruits are apyrenes, that is, without seeds, or with sterile seeds. Partenocarpy in some species (Corinthian grape, fig, etc.) is determined by internal causes, for example, pollen-grains whose tube does not reach the ovule or which, while remaining in contact with the stigma, do not germinate, whereas in other species is induced by external agents. The artificial means capable of determining the parthenocarpy are the contact with the stigma of pollen mush, also of other plant species, of mineral powders (sulfur, etc.). The puncture of an insect on the ovary or the infestation of parasitic fungi can sometimes determine the parthenocarpy.
The fruits that are formed through this process are all those in which the growth takes place (or can happen) therefore independently of pollination. This process is made possible by the presence of gibberellina, which is a vegetable hormone that allows its maturation.
Another aspect consequent to the parthenocarpic event is frequently the appearance, the taste, the form or other characteristics that differentiate the fruits formed as a result of fertilization by the fruits in the absence of this.
In nature, parthenocarpy is not a widespread phenomenon because, if the purpose of the fruit is to allow the reproduction of the plant, the generation of a fruit without seeds seems very paradoxical; in normal physiological conditions, in fact, one would have the abortion of the parts of the flower or of the fruit that have not been fertilized. For this reason the parthenocarpic process could be classified as a degeneration of the plant reproductive system; but often plants that produce parthenocarpic fruits are preferred and selected in agriculture for commercial reasons. This is the case of bananas (due to the absence of seeds) or figs that do not have to support a complex and difficult or even impossible reproductive system under certain conditions. The fruits formed in the absence of seeds are called apirenes.
There are two types of parthenocarpy: complete or partial. In the case of complete parthenocarpy the fruit is never fertilized; in the partial the fruit can be fertilized but it matures equally even if it is not. In cases of complete parthenocarpy, this is often generated by a concomitant Polyploidy, the possibility of sexual reproduction being completely compromised. Furthermore, the parthenocarpy can involve an entire botanical species or, more frequently, only some varieties or mutations of this species.
Typical examples of parthenocarpic fruits are some varieties of kaki, fig, vine, pineapple, and all the varieties of bananas marketed.