Kentucky Bluegrass Germplasm Evaluation for Turfgrass Quality and Grass Seed Production Without Open-Field Burning.

Open-field burning of Kentucky bluegrass (Poa pratensis L.) post-harvest residue, which maintains grass seed yield and stand longevity, has been eliminated in Washington and is restricted in Idaho and Oregon. Our objective was to develop Kentucky bluegrass germplasm that has sustainable seed yield without field burning while maintaining acceptable turfgrass quality. The study consisted of eight PI accessions and two check cultivars (‘Kenblue’ and ‘Midnight’). Accessions were previously selected for both seed yield without field burning and turfgrass quality. In a space-plant nursery at Pullman, WA, several agronomic yield parameters were evaluated over a 2-year period and individual plants were reselected within each accession, or check, with the highest seed weight, highest seeds panicle-1, highest panicle number area-1, and highest seed yield. Remnant seed from the original populations were also included. Turfgrass plots were established in 2006, 2009, and 2010 at Pullman, WA, Auburn, AL, and Puyallup, WA, respectively. Seed production plots (irrigated and non-irrigated) were established at Pullman in 2007. The turfgrass trials were evaluated according to National Turfgrass Evaluation Program protocol. Seed production plots were harvested 2008 to 2011. Selection for seed yield components had a variable response and seed yield was more dependent on accession. Among the 50 entries, PI 368241, selection panicles area-1, and Kenblue, selection seeds panicle-1, had the best sustainable (four harvests) seed yield without field burning in both non-irrigated and irrigated seed production. Both had fair turfgrass quality. PI 371775, selection seeds 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 showed acceptable turfgrass quality at Puyallup. It also may have stress, i.e., heat and bermudagrass (Cynodon dactylon [L.] Pers.) invasion tolerance, as all five PI 371775 entries placed in the top 10% for turfgrass quality during a 2-yr trial at Auburn, AL. These three selections are currently in seed increase. Germplasm should be released by 2014.