Seed Priming Does Not Improve Corn Yield in a Humid Temperate Environment

Early emergence and stand establishment of corn (Zea mays L.) is considered to be one of the most important yieldcontributing factors in eastern Ontario. A pot experiment and two field experiments were conducted in Ottawa, Canada, to evaluate the effects of seed priming with water, osmotic solution (2.5% KCl), and plant growth regulators (indole acetic acid, cytokinin, ethephon and gibberellic acid) on emergence, seedling vigor, N response, and grain yield of corn. Time to seedling emergence, seedling vigor, and growth were measured in a pot experiment under a greenhouse condition while field performances, N response, and grain yield were determined in field experiments. In the greenhouse study, none of the treatments were better than the unsoaked control. Under field conditions, both hybrids and N application had significant effects on grain yield, but there was no yield advantage due to any of the seed treatments. Seed soaking with 20 ppm gibberallic acid (GA3) solution for 30 min improved seedling vigor (i.e., seedling height and growth), but this was not translated into greater grain yield. Seed soaking with water for 16 h significantly reduced percentage emergence and final plant stand in 2002 while in 2003, seed soaking with 2.5% KCl and 20 ppm GA3 solution for 16 h significantly reduced plant stand and grain yield under the 150 kg N ha-1 treatment. Despite some positive effects of seed priming on seedling vigor and stand establishment, none of the seed-priming treatments tested showed beneficial effects on grain yield and N efficiency under the temperate-humid conditions such as in eastern Ontario.