Winter wheat straw and grain production in response to trinexapac-ethyl and nitrogen fertilizer

Managing winter wheat (Triticum aestivum L.) for both grain and straw production is a common practice, especially where cropping and animal systems are integrated, with wheat straw being used for animal bedding. Trinexapac-ethyl (TE) is a common plant growth regulator used in winter wheat and has been studied for its potential to mitigate lodging risk and improve grain yield but its influence on straw yield and quality still needs to be elucidated. Here, we evaluated the effect of TE (control, single, and split application) in combination with three spring nitrogen (N) fertilizer rates for a total of nine treatments over two growing seasons in Pennsylvania. Compared to the control, the application of TE reduced plant height without increasing basal internode diameter, which led to an 8% decrease in straw yield when TE was split applied and a 5% decrease (although not significant at p = 0.05) in straw yield when TE was applied in a single dose. TE did not affect straw water holding capacity, thus preserving its value for animal bedding. No lodging was observed across both growing seasons, and grain yield was not affected by treatments, similar to other studies where TE did not provide a grain yield benefit in the absence of lodging. Grain protein concentration increased with increasing N fertilizer rates, which were achieved through late spring N applications. When considering the use of TE, winter wheat producers must weigh the potential tradeoff between grain and straw yield, although grain and straw quality are maintained.