b'Branding and marketing Kisy by variety is unusualcreated diploid plants, which do not produce female in an industry where products are overwhelminglyflowers thereby reducing the chances of two diploidConsumer marketed as a commodity. Unlike agricultural cropsmelons producing seeded fruits.that are marketed and purchased by variety, the onlyTo grow the seedless watermelons preferred bypreferences differentiation consumers appreciate is whether or notconsumers, a seeded pollinator watermelon with male a melon is seedless. The story behind seedless water- flowers must be a companion to the seedless plants,vary melons involves alterations to the plant genome itselfwhose pollen is not viable.enormously through mutation breeding.Growers frequently use bees to facilitate pollina-tion," explains Greg Johnson, a University of Delawarearound Watermelon Development and SeedlessExtension vegetable and fruit specialist. "Watermelonsthe world. Watermelons are a native desert plant. They like heat and tolerate In 1939, plant breeders successfully developed tetra- dry conditions, but to obtain good melon yields, theyDeveloped ploid watermelon plants with four copies of eachrequire pollination and frequent irrigations." markets chromosome in each cell. When these tetraploid"Public plant breeders are usually focused more plants are crossed with ordinary diploid melons, theon prebreeding, and private breeders work more onsuch as the resulting melon plants were triploids with three setscultivar development," says Todd Wehner, Department of chromosomes. Triploids cannot produce seedsof Horticultural Science at North Carolina StateUnited States, because their reproductive cells require an evenUniversity. "Public roles are research and training.Europe, number of matching chromosome sets. The result wasPrivate goals are cultivar release and sales support. "seedless" watermelons. What appears to be whiteFunding at NC State, for example, has shifted fromAustralia, and seeds are merely empty seed coats, not viable seeds. federal Hatch support and funds from North CarolinaJapan prefer Maintaining the tetraploid parent lines by treatingto grants from the USDA and other groups. As a result, seedlings with colchicine is the most difficult part ofresearch has moved toward other high-value crops.seedless producing seeds for a tetraploid watermelon. BecauseRoyalties are not easily obtained for most vegetable of the difficulty in maintaining the parental lines andcrops including watermelons."watermelon, the usual practices needed to produce hybrid seeds,For plant breeders, flavor is a crucial goal of virtu- and the trend seed for seedless watermelons is quite expensive,ally every breeding program but not the only objective. as much as $150 per 1,000 seeds. Because of theA perfect-tasting variety without an effective fungal,is moving expense of the seeds, most tetraploid plants arevirial, and bacterial disease resistance package will nottowards started as transplants.be successful with growers. Functional commercial Germination of tetraploid seeds is usually not asyield components, including shelf life and consistentsmaller sizes good as standard cultivars, even under ideal condi- fruit size are important to both growers and shippers.and fresh-cut tions. A crop of seedless fruit involves the participationPrivate plant breeders continually develop of melons with three different genomes. To increaseimproved varieties to assure that consum- options.the success rate of pollination, plant breeders haveers everywhere will continue to enjoy fla- Isabel Cayuela vorful watermelons and continue to knowZamorawhat angels eat.SW58/ SEEDWORLD.COMFEBRUARY 2020'