EFFECTS OF GIBBERELLIC ACID-POTASSIUM NITRATE SEED TREATMENTS ON EARLY SEEDLING GROWTH IN 2 WHEAT CULTIVARS

Rapid and vigorous seedling establishment in wheat (Triticum aestivum L.) is of major importance in the southeastern United States, where unfavorable conditions for optimal seedling establishment frequently occur. Seed treatments with various compounds are known to improve seed germination and seedling growth in other crops and may offer a simple and inexpensive method to improve stand establishment and grain production in wheat. Aqueous solutions containing all possible combinations of three concentrations (0, 1, 10 mM) of gibberellic acid, A3 (GA), and two concentrations (0.0, 0.3 M) of potassium nitrate, KNO3 (PN), were prepared. Seeds from two adapted wheat cultivars ('Florida 301', 'Florida 302') were submerged in one of the six solutions for 2 h, drained, and dried for at least 24 h at room temperature. The dry seeds from each of the 12 seed treatment-cultivar combinations were then placed in growth pouches containing 20 mL of deionized water. The pouches were then placed in a constant temperature chamber (20-degrees-C, dark, 100% relative humidity). At 5, 7, and 9 d after germination initiation (days of measurement), the germination percent (GP), coleptile length (CL), root length (RL), primary leaf emergence percent (PLEP), and primary leaf length (PLL) were determined for each of the 12 seed treatment-cultivar combinations. For GP, highly significant GA and PN main effects were found with the highest GA concentration substantially increasing GP, and the addition of PN slightly reducing GP. For GP, the GaxPN interaction and all interactions involving cultivar and day of measurement were not statistically significant. In general, the addition of GA and/or PN increased CL, decreased RL, increased PLEP, and increased PLL. A statistically significant synergistic GaxPN interaction was found only for CL. Statistically significant cultivar main effects and cultivar interactions with seed treatment and day of measurement, were obtained for CL, RL, PLEP, and PLL. Apparently, the cultivar or genetic component is a major factor in the seed treatment response and, as a result, must be considered in selecting the most effective GA-PN combination and in developing the most appropriate breeding and selection strategy. Before field recommendations can be made, the relationship between these controlled laboratory results and field seedling establishment must be evaluated.