Which sterility is exploited in hybrid seed production?

Cytoplasmic and genetic male sterility is exploited in hybrid seed production.
Cytoplasmic male sterility (CMS), a condition under which a plant is unable to produce functional pollen, is widespread among higher plants. CMS systems represent a valuable tool in the production of hybrid seeds in self-pollinating crop species, including maize, rice, cotton and several vegetable crops.
Genetic male sterility (GMS) has emerged as an ideal tool to accelerate hybrid breeding. Male sterility is generally characterized by the impairment of male reproductive development as a result of underlying genetic causes and leads to the malformation of male gametes and/or pollen.