How Are Seedless Orange Trees Started?
New seedless orange trees are started by grafting buds from fully grown seedless orange trees to rooted seedlings that were grown from the seeds of other citrus trees. In the grafting process, the bud is inserted in a slit made in the bark of the host tree.
When the bud has begun to grow, the top of the host tree is cut away close to the graft. The grafted bud continues to grow into an orange tree that will also bear seedless fruit. The root system of the host tree supplies food and water for the growing plant. Most kinds of oranges contain seeds.
In some plants, however, fruit develops without fertilization, a phenomenon known as parthenocarpy. Parthenocarpic fruit has advantages over seeded fruit: longer shelf life and greater consumer appeal.
In many plants, self-incompatibility genes limit successful fertilization to cross-pollination between genetically different male and female parents. This property is exploited by citrus farmers who grow seedless fruits, such as navel oranges and clementines.