Although at first glance this seems describe the next generation of Formula 1 racing engines, it is in fact a term used in genetics and more specifically selective breeding. In this instance the F1 stands for Filial 1, which describes the first filial (or first generation) of seeds or plants resulting from a cross pollination of distinctly different and genetically pure parent plants. The resulting progeny or offspring of these distinctly parents produces a new, uniform variety with specific and/or desirable characteristics from either or both parents. Using distinctly different parents will also creates a genetic lock as it is now almost impossible to recreate these characteristics to the next generation through the propagation of viable seed known as an F2 hybrid.
The main benefit of this hybridisation technique is to guarantee the characteristics of the crop sown, but it also produces continuity of size and shape as well as Heterosis, more commonly known as 'hybrid vigour'.
Hybrid vigour is the result of genetic breeding where the dominant genes from one parent plant are used to suppress the undesirable recessive genes of the second parent plant. The resulting seedlings will be larger and stronger than either of the parents as well as generally showing better disease resistance.
It requires a certain amount of research, technical support and field study to produce a worthy F1 hybrid, which is why you will find that any seed packets displaying this term will be noticeably more expensive compared to traditional cultivated varieties.