sexual propagation, reproduction by seed involving the union of male and female sex cells (pollen and ovule respectively). The important feature of this type of propagation is that the parent plants are genetically different, so the seedling is in turn genetically different from either parent. Throughout the world of nature, this is how genetic diversity is continued, permitting selection of those progeny best suited to survive. In commercial viticulture, this process has been circumvented by propagating selected, desirable individuals and propagating them vegetatively (see vegetative propagation). Originally sexual seedlings, all grape varieties have been propagated asexually for many years, decades, or centuries with substantially the same genetic constitution. Sexual propagation is used for vine breeding throughout the world to produce new varieties. Success depends on selecting suitable parents, and many years of painstaking evaluation.
