Apomixis is the production of seeds without fertilization. In apomixis, seed production takes place without the fertilization of egg cell and the sperm nucleus. Apomixis is an asexual method of reproduction. Seed formation takes place without zygote formation.
The apomixis that are generally observed in plants are:
Recurrent apomixis: In this, embryo formation takes place without meiosis and syngamy (fusion of sperm nucleus and egg cell) from the diploid mother cell. This takes place in onions and Fragaria.
Non-recurrent apomixis: Formation of embryo takes place without fertilization directly from the egg or other haploid cell. This takes place in apple.
Adventive embryony: Adventitious embryony is also known as sporophytic budding. In this embryo development takes place from a diploid cell other than the megaspore mother cell. It is derived from the cells of nucellus or integuments of the embryo sac. This takes place mostly in citrus fruits and sometimes in mango.
Vegetative apomixis: In this, instead of flower formation, other vegetative propagules are present such as bulbils. For example, in Agave and Fragaria.
Parthenocarpy is different from apomixis as in apomixis seed formation takes place but without fertilization. On the other hand in parthenocarpy, seeds are not produced at all. Pollination and fertilization are absent in parthenocarpy.
Examples of parthenocarpic fruits are grapes, pineapple, banana, etc. Parthenocarpy is utilized in agriculture to produce seedless fruits such as watermelon.