vine breeding, the crossing of one vine variety or species with another to produce a new variety. Grapevines are highly heterozygous outcrossers and do not breed true from seed, which is the reason for their universal vegetative propagation. If both parent varieties belong to the same species (in practice, usually the European vinifera) of the vitis genus, then the result is commonly called a cross (occasionally crossing), while the results of crossing varieties from more than one species (typically, a V. vinifera variety and a member of an american vine species) are commonly called hybrids.
