Most watermelons produced in South Carolina are seedless, but how are they produced if they don’t make any seed?
By seed, of course.
The process of growing seedless watermelons was explained during the 2019 Clemson Watermelon Field Day at the Clemson Edisto Research and Education Center (REC) by Clemson University horticulture professor Jeff Adelberg.
“Seedless watermelons are grown from seeds that are produced by crossing watermelon lines to produce plants that have an odd number of chromosomes,” Adelberg said. “Because of the odd number of chromosomes, these plants are sterile and do not produce mature seed.”
Most seedless watermelon production starts with transplants, or seedlings grown from seed in a greenhouse. Precise control of temperature and moisture are critical for the plants to emerge. Clemson and North Carolina State University have created a step-by-step guide to seedless transplant production for growers and home gardeners.
People growing seedless watermelons in home gardens can plant one seeded watermelon per two seedless watermelons to ensure pollination.
Commercial growers and seed companies use hand-pollination, resulting in higher costs for seedless watermelon seed, which can run $150 per 1-pound pack compared with $25 per 1-pound pack for standard watermelon varieties.
“People sometimes find white ‘seed’ in seedless watermelons,” Adelberg said. “These are coats of seed that did not fully mature and are safe to swallow.”
About 80 percent of watermelons produced in South Carolina are seedless.
Information from the Watermelon Board shows seedless watermelons were invented more than 50 years ago by H. Kirata, a Japanese scientist and professor at Kyoto University. Seedless watermelons look and taste like ordinary watermelons minus the black seed.
Watermelons are nutritious and are used to “fuel athletes.” Gilbert Miller, Clemson Extension vegetable specialist at the Edisto REC, and 2019 South Carolina Watermelon Queen Courtney Kubu shared some facts about the tasty treat
“Watermelons are as healthy and nutritious as they are delicious,” Miller said. “Watermelons are natural sources for water, vitamins and certain nutrients. Studies have found athletes can eat watermelon during sporting events to rehydrate, as well as improve circulation, keep electrolytes in balance and boost performance.”
The nutritional value is about the same for seeded and seedless watermelons, Miller said. Nutrition facts from the United States Department of Agriculture shows each 1 cup serving of watermelon contains: 46 calories, 0g fat, 2mg of sodium, 12g of carbohydrates, 1g of protein, 10mg of calcium and 169mg of potassium.
Miller also talked about growing hemp after watermelons in the same fields, as well as watermelon topics from A to Z, which included how to control insects and diseases. Insect and disease control information can be found in the Clemson Cooperative Extension Service’s Watermelon Spray Guide for 2019.
Watermelon is a sweet, juicy summertime favorite and is available at supermarkets, farmers markets, roadside markets and other places where produce is sold, Kubu said.
Other topics covered during the field day included a report from the South Carolina Watermelon Board and South Carolina Watermelon Association by Kyle Tisdale, marketing specialist with the South Carolina Department of Agriculture. Alex Butler of the South Carolina Department of Health and Environmental Control gave an update on the Western Capacity Use Area, an area established in November 2018 where groundwater withdrawal permits are required to use groundwater equal to or greater than 3 million gallons in any month in affected counties. A management plan is being developed to be used to guide the initial groundwater management strategy and provide direction for future groundwater management goals.
“The goal of this program is to make sure everyone gets the water they need in order to function each day,” Butler said.
Matt Cutulle, a weed scientist, addressed weeds and weed management for watermelon crops, while Joe Mari Maja, a sensor engineer, updated attendees on research he is conducting involving using Unmanned Ground Vehicles (UGVs) for watermelon harvest. Ben Hinson of the TriEst Ag Group gave an update on grafted watermelon research, particularly Carolina Strongback, a rootstock watermelon that is resistant to Fusarium wilt and the southern root-knot nematode, yet performs and produces well.
Additional information will be available at the annual Fall Vegetable Field Day at the Edisto REC, where Miller and guests will discuss proper techniques for growing fall vegetables. A date and time for the fall field day will be announced later.
Prepared by Denise Attaway, Clemson University College of Agriculture, Forestry and Life Sciences; Public Service and Agriculture.