COLLEGE STATION — Sometime just before Thanksgiving 1999, the ultimate Texas sweet potato may be pulled from the ground and shipped to market — it and tens of thousands just like it.
One of the best sweet potatoes produced in 1996 was successfully cloned this year — making about 16,000 copies of it — and field trials indicate that the test tube tubers held true to the quality of the sweet potato from which they were made. Cloning and growing of those offspring in numbers enough to produce seedstock for the East Texas farmers is likely next spring for planting of a commercial crop of the clones in 1999.
The cloning shaves about 10 years off traditional variety breeding methods, according to Dr. Leonard Pike, horticulturist and director of the Vegetable Improvement Center at Texas A&M University where the sweet potato was cloned.
“The procedure that he did proved that it is possible to reproduce a very good yield producing plant through cloning,” said Richard Stewart, a grower from Van Zandt County.
Production problems heightened last year when the harvest dig turned up an abundance of mal-formed, oversized sweet potatoes unfit for the fresh market. Farmers in Van Zandt, Rains and Wood counties where the bulk of the crop is grown saw quality concerns and urban encroachment from Dallas just 50 miles away shadowing their livelihood and decided science might yield some answers to keep the $11 million-a-year industry alive.
They found Pike, creator of the famous 1015 onion and widely anticipated maroon carrot, who admits that sweet potatoes were not a crop with which he had much experience.
But Pike, curious whether environmental conditions or genetic changes were causing the problem, decided to take a stab at finding an answer. He adapted his onion cloning techniques in his College Station lab. The result was that from March until October, one sweet potato turned into 16,000 identical sweet potato slips that were planted, harvested and critiqued from plots at College Station and Overton. From the College Station harvest, Pike determined that environmental issues were not to blame. Three of the best individuals from that field were chosen for cloning, which will begin in February.
“I was somewhat impressed with the works he’s done,” said Dale Smith, a grower from Fruitvale, about Pike’s experiment. “The jury is still out on whether we will see a lot of improvement, but we are headed in the right direction.”
To the consumer, a “perfect” sweet potato is 2-1/2 inches around and 6- to 8-inches long. It will have smooth skin and a good color, and be high in vitamins A and C, beta carotene and potassium, according to Marty Baker, Texas Agricultural Extension Service horticulturist in Overton where sweet potato field trials have been conducted for 22 years. In addition, farmers want a sweet potato variety that will yield high tonnage per acre, 2,000-2,800 pounds per acre.
But what consumers and East Texas farmers have been seeing is far from perfect. During the 1990s, the seed potatoes purchased largely from Louisiana, North Carolina and Mississippi sources, began producing a disproportionate number of off types — potatoes too large, too small or too big around to be used as bakers. The problem worsened and by 1996, fully half of some year’s crops had to be classified as canning potatoes, according to Baker.
Prior to the early 1990s, East Texas growers could sell their off-types to canneries in Louisiana and make enough to cover some of their production costs. But increased sweet potato production in that state an dothers began to swamp the canneries in the mid-1990s, and growing too many off-types became a losing proposition.
The cloned sweet potato provides some opportunity to correct all that.
Smith said growers next will have to decide on how to fund the cost of cloning sweet potatoes slips on an annual basis.
Stewart said some legalities may need to be addressed as sweet potato seedstock must be produced in a certified sweet potato weevil- free area, which College Station is not. That may be averted, Pike said, if the slips are transported from the lab in test tubes to the field for planting, but such a ruling has not been broached with the Texas Department of Agriculture at this time because the experiment only recently was completed.
“When I get to talking about sweet potatoes, I get a little hyper,” Smith said. “I’m supportive of the research, and I’d be willing to do whatever is necessary to continue the work.”
Smith and Stewart agreed that growers of the nearly 6,000 acres in Texas most likely will decide individually rather than as a united group whether to pursue cloned sweet potatoes for future plantings.