Effect of Trinexepac-Ethyl Plant Growth Regulator on Wheat Yield.

Growers in the high rainfall production zones of Oregon are accustomed to applying plant growth regulators to seed crops. Trinexepac-ethyl (TE) is a plant growth regulator that inhibits gibberellic acid biosynthesis which has resulted in a positive effect in controlling plant height and improving yield in grass and legume seed crops. With the recent introduction of Palisade EC^® in the cereal market, wheat growers are interested in using TE to increase wheat yields.  In the fall of 2012, a multi-location study was initiated to determine if TE increased wheat yields in the high rainfall and irrigated production regions of Oregon. At each site a randomized complete block design with four replications was used.  Treatments consisted of three wheat varieties, two nitrogen (N) rates, and four TE rates and/or timings. Preliminary results indicate that TE did not increase grain yield or test weight with or without additional N.  Additional N increased grain protein, but there was no effect on grain protein from TE.  Trinexepac-ethyl applications did significantly reduce plant height.  However, the timing of TE application did affect the amount and consistency of height reduction.