Using Gibberellic Acid to Stimulate Late-Planted Winter Wheat.
Alexander D. Pavlista, University of Nebraska-Lincoln, University of Nebraska, Panhandle Research @ Extension Center, Scottsbluff, NE 69361 and David Baltensperger, 434 Heep Center - 2474 TAMU, Texas A&M University - Soil & Crop Sciences, Texas A&M University, Department of Soil and Crop Sciences, College Station, TX 77843-2474.
Introducing winter wheat into irrigated cropping systems is limited by the overlap of optimal planting dates and harvest dates of some summer crops. The purpose of these studies were to determine the feasibility, rate and method of application of gibberellic acid (GA3), a natural hormone, to stimulate the growth and establishment of late-planted winter wheat. Growth chamber studies were conducted to determine the dose, application and cultivar sensitivity to GA3. Temperature regiments were 50/40 F representing cooler conditions in Sep. Seed soaking with GA3 at 500 ppm stimulated seedling growth within a few weeks. The growth of all cultivars was stimulated by 250 or 1000 ppm GA3 soak with the most responsive being the non-semi-dwarf lines, cultivars Buckskin, Goodstreak and Scout66, and the semi-dwarf InfinityCL. During the 2005-2006 season, field trials were conducted in the Nebraska Panhandle. Seeds of cultivars Goodstreak and Wesley were soaked with or without 1000 ppm GA3, and planted on 14 Sep, 28 Sep and 12 Oct, 2005. Growth stimulation by GA3 overcame the two-week delayed planting. At harvest, the yield of GA3-treated wheat planted on 28 Sep were similar to untreated plants seeded two weeks earlier. Application of GA3 to seed as a soak or spray did not differ and furrow application was not economical. GA3 could be used as a seed applied tool to allow winter wheat to establish itself when planted two weeks later than optimum and there would be no loss in yield.