Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

Pollen grains of a flower do not germinate on the stigma of the same flower due to presence of self sterile genes. This condition is called self-incompatibility. e.g. Tobacco, Patato, crucifers etc.
In self-incompatible species, self-pollination does not lead to seed formation because self-compatibility is a genetic mechanism and prevents self pollen from fertilizing the ovules by inhibiting pollen germination or pollen tube growth in the pistil.