Trinexapac-Ethyl and Burning Effects on Seed Yield Components in Strong Creeping Red Fescue

Open-field burning has been used to remove post-harvest residue for high seed yield and quality in strong creeping red fescue (CRF) (Festuca rubra L. subsp. rubra) but concern over air pollution and safety issues has resulted in legislatively mandated reductions of this practice in Oregon. The effects of spring and fall applications of the plant growth regulator trinexapac-ethyl (TE), and burning (burn) and mechanical removal (flail) of post-harvest residue on seed yield components, were evaluated in strong CRF over a 4-yr period. Response to treatments was different among years but burn was critical for maintaining high potential seed yields as the stand aged. Burn increased panicles m(-2) and spikelets panicle(-1) by up to 120 and 22%, respectively, over flail, and in turn, resulted in higher seed yields. Spring TE applications increased florets spikelet(-1) by up to 14% in Years 1, 3, and 4. Fertile tiller height and lodging were reduced by spring-applied TE. The combination of burn and spring TE produced highest seed yields in Years 3 and 4 as a result of increased seed number m-2 and seed weight. Fall TE did not affect seed yield components or yield and therefore, is not an effective management tool in strong CRF seed production.