Edible banana fruit is seedless because of

Edible banana fruit is seedless because of Vegetative parthenocarpy.
Parthenocarpy is the development of fruit without fertilization. It is the natural or artificially induced production of fruit without fertilization of ovules, which makes the fruit seedless.
The fruit resembles a normally produced fruit but is seedless. Varieties of pineapple, banana, cucumber, grape, orange, grapefruit, persimmon and breadfruit exemplify naturally occurring parthenocarpy.