AgriLife researchers study vegetable ‘transplant shock’

Research at the Texas AgriLife Research and Extension Center in Uvalde includes investigating the application of gibberellic acid, or GA, a growth-stimulating hormone found naturally in plants, on artichokes. GA is used to help the artichoke plant induce bolting in higher-thanneeded temperatures by mimicking the physiological effects of cold weather on the plants. (Photo courtesy of Texas AgriLife Research) UVALDE – Dr. Daniel Leskovar, a Texas AgriLife Research plant physiologist at the Texas AgriLife Research and Extension Center in Uvalde, has been investigating ways to help vegetable plants make a less stressful transition from the greenhouse to the field.

“This research can aid in the successful production and further profitability of some vegetable crops by producing high-quality, more adaptive plants that will establish well," Leskovar said. "It could also enable some vegetable plants to produce beyond their regular season or succeed within a stressful growing environment.”

Texas Agrilife Master Gardeners Jeff Miller, Mary Foucheux, Elaine Trefry, Kay Serifin, Charlene Manning, Carole Huebner, Brenda Savelle, Laminda Coker, and Charlie Patin. Contributed photo An expert in vegetable physiology, Leskovar said his research has been “centered in the identification and understanding of plant adaptation mechanisms to temperature, water and biological stresses as part of an integrated vegetable cropping system.” He and his collaborators already have been successful in creating heartier pepper, tomato, watermelon and cantaloupe seedlings for transplantation.

“Our work has primarily involved modulating naturally occurring growth regulators in vegetable plants,” Leskovar said. “One of these is abscisic acid, or ABA, which is a hormone naturally produced by the plant.

"Abscisic acid affects the closing of plant stomates and controls plant physiology such as leaf transpiration," he said. "The hormone also slows plant growth temporarily, which is important for producing compact transplants.”

In many southern regions of the U.S, high temperatures, dry winds and rapidly drying soil after planting are detrimental to or impair the early growth of vegetable transplants, Leskovar said.

Research efforts to date have shown that external application of abscisic acid to cabbage, watermelon and pepper transplants had reduced undesirable excess shoot growth during plant development in the greenhouse environment, Leskovar said. They also show that its application on pepper, tomato and artichoke seedlings was superior to that of other commercial “film-forming antitranspirants” in improving overall plant water status.

“Practices that reduce plant transpiration have the potential to enhance stand establishment, thus conserving soil moisture and reducing irrigation frequency,” Leskovar explained. “Abscisic acid appears to be useful for conditioning vegetable seedlings to withstand temporary stress from water deficiency and to improve stand development under stressful conditions.”

He said vegetable transplants quickly recovered their water potential, stomatal efficiency and photosynthetic rates, and resumed their growth after a short period of water stress in response to the external application of the hormone.