Full explanation
F1 ≠ 'hybrid' in everyday language: F1 is a generation (the first), hybrid is a cross type. In commercial usage they're synonyms: on a 'corn hybrid DKC 3969' pack, F1 seed is automatically implied. F2 (second generation from F1 seed) shows trait segregation — uniformity is lost, yield drops 25–50%, tolerance becomes unstable. That's why re-sowing F1 from the harvested crop is unacceptable for hybrids. In F1 seed production: a sterile-based mother line (CMS — cytoplasmic male sterility in sunflower, corn, rapeseed) is pollinated by a father line; result — F1 for sale. Ukrainian turnkey hybrid seed producers: Corteva Agriscience Ukraine (seed plant at Stasi, Poltava oblast), MAS Seeds (Kirovohrad oblast), Syngenta (Khmelnytsky).