Where does seedless fruit come from and how does it reproduce?
Most seedless fruit comes about the same way as other fruits, which commonly are grown from cuttings or grafts and not seeds. To make a cutting, a branch or vine is cut from a plant, fed a nutrient mixture, and put in dirt, where leaves and roots form. In a graft, the branch, vine, or bud is grown right into another plant’s trunk or rootstalk. With the exception of seedless watermelons, which have a complicated propagation method, seedless fruit can’t reproduce on its own—it must be grafted each time.
Seedless fruit originated from genetic mutations that humans discovered and cultivated. For example, seedless navel oranges date back to the 19th century and a single mutant tree in Brazil, whose progeny all come from buds grafted onto other citrus trees.
Scientists are working continually to produce new varieties of seedless fruit, either by breeding different varieties together or by stimulating genetic mutations. In recent years, they have created some seedless citrus crops by irradiating plant seeds, which causes mutations. Some of these mutations are fatal to the plant, some are benign; but sometimes these irradiated seeds produce a suitable seedless fruit, and the plants are propagated through budding.
Researchers may have to look at thousands of seedlings to find a plant that’s not only seedless but also attractive to farmers and consumers. David Ramming, a research horticulturalist with the USDA research center in Parlier, California, was involved recently in the introduction of two new species of grapes, the Sweet Scarlet and the Scarlet Royal. He says the goal is to create disease-resistant seedless fruit that tastes good and can be grown in different hemispheres. “We’ve got new varieties in the works all the time,” says Ramming. “We’re trying not just to have seedless fruit that tastes good, but to make it available to grocers all year round.”