Sustainable Kentucky Bluegrass Seed Production Without Field Burning.

Open-field burning of Kentucky bluegrass (Poa pratensis L.) post-harvest residue has been eliminated in Washington and is severely restricted in Idaho and Oregon. The objective of our study was to develop bluegrasses that have sustainable seed yield without post-harvest field burning and still maintain acceptable turfgrass quality. This long-term study consisted of 10 Kentucky bluegrass entries; eight are USDA/ARS Plant Introduction (PI) accessions and two are commercial cultivars (‘Kenblue’ and ‘Midnight’). The selected PI accessions, in previous research, had expressed high seed yield without burning of post-harvest residue and good turfgrass quality. Several agronomic yield parameters were then evaluated over a 2-yr period and individual plants were reselected within each accession, or check, with the highest seed weight, highest seeds panicle-1, highest panicles area-1, and highest seed yield. Remnant seed of the original USDA/ARS population were also included. Turfgrass plots were established in 2006 at Pullman and 2010 at Puyallup, WA. Seed production plots (irrigated and non-irrigated) were established in 2007 at Pullman, WA. The turfgrass trials were evaluated according to NTEP (National Turfgrass Evaluation Program) protocol to determine turfgrass quality. Seed production plots were harvested (2008 to 2011) and clean seed yield was determined. Results indicated that reselection for seed yield components had a variable response and seed yield was primarily dependent on accession. Among the 50 entries, PI 368241, selection panicles area-1, showed the most promise of being able to provide long-term turfgrass seed yield without field burning in both non-irrigated and irrigated seed production. Kenblue, selection seed panicle-1, had good seed yield and fair turfgrass quality at Pullman. PI 371775, selection seed panicle-1, had good turfgrass quality while maintaining good seed yield with irrigation. Although Kentucky bluegrass is not recommended as a turfgrass for western WA, PI 371775, selection seed panicle-1, showed acceptable turfgrass quality at Puyallup. These three selections are currently in seed increase at Pullman, WA and germplasm should be released by 2014.