Distinction between Polyembryony and Parthenocarpy:
Polyembryony refers to the development of more than one embryo within a single ovule or seed. These additional embryos can originate from various sources: cleavage of the zygote, synergistic cells, antipodal cells, or somatic cells of the nucellus or integuments. The embryos may be genetically identical (apomictic) or sexual. This phenomenon concerns embryo and seed formation.
Parthenocarpy, in contrast, is the development and maturation of a fruit without prior fertilization. This results in the formation of seedless fruits. This phenomenon specifically relates to fruit development, independent of sexual reproduction and successful seed set.

Classification of Parthenocarpy:
Parthenocarpy can be classified based on its induction:

1. Vegetative Parthenocarpy: Fruit development occurs spontaneously without any pollination stimulus. Examples include some cucumber varieties and navel oranges.
2. Stimulative Parthenocarpy: Pollination is required to initiate fruit development, but fertilization does not occur. The pollen, or the act of pollination, stimulates the ovary to mature. This is observed in some grapes and watermelons.
3. Chemical Parthenocarpy (Artificially Induced): This involves external application of plant growth regulators, typically auxins or gibberellins, to flowers. This chemical stimulus bypasses both pollination and fertilization, inducing seedless fruit development. This method is used in commercial cultivation of grapes and tomatoes.

Significance of Parthenocarpy:
Parthenocarpy holds immense agricultural and economic significance. Its primary benefit is the production of seedless fruits, which are highly desirable for consumers, enhancing palatability, ease of consumption, and culinary convenience (e.g., seedless grapes, bananas, watermelons). This feature significantly increases commercial value. Furthermore, parthenocarpy ensures consistent fruit set and yield in environments where natural pollinators are scarce or under unfavorable conditions that impede successful fertilization, offering a reliable method for fruit production.