Influence of Plant Growth Regulators and Nitrogen Rate on Soft Red Winter Wheat Growth and Yield.

Excessive spring nitrogen (N) applications on wheat (Triticum aestivum L.) may result in reduced stem rigidity leading to plant lodging prior to harvest. Lodged wheat may reduce grain quality due to inhibition of nutrient transport from roots to grain or decrease grain yield through the inability to thresh lodged plants. Palisade (trinexapac-ethyl) is a newly labeled plant growth regulator for wheat production in Michigan and was designed to decrease internode length and increase stem thickness to reduce opportunities for plant lodging. A field study was initiated in 2014 to determine the effects of trinexapac-ethyl and N application rates on soft red winter wheat growth and yield. The study was arranged as a split-plot randomized complete block with four replications.  Main plots consisted of four rates of nitrogen applied at green-up (0, 84, 118, and 151 kg N ha^-1) while sub-plots consisted of with or without trinexapac-ethyl applied at Feekes 6 (0.88 L ha^-1). Data collection included bi-weekly chlorophyll meter readings, tissue testing at Feekes 9, plant height and head counts at physiological maturity, and lodging ratings throughout the growing season. In 2014, trinexapac-ethyl application significantly reduced plant height and peduncle length by 5.1cm and 4.3cm, respectively. A significant 254 kg ha^-1 yield increase was observed in those plots where Palisade was applied as compared to plots with no Palisade. Data collection is currently underway for study year two and results will be presented.