Development of Turf-type Poa pratensis L. Germplasm for Seed Production without Field Burning

Open-field burning of Kentucky bluegrass (Poa pratensis L.) postharvest residue, which maintains grass seed yield and stand longevity, has been eliminated in Washington and is restricted in Idaho and Oregon, USA. Our objective was to develop Kentucky bluegrass germplasm that has sustainable seed yield without field burning while maintaining acceptable turfgrass quality for use as an amenity grass. From the USDA/ARS Poa pratensis L. Plant Introduction (PI) collection, 228 accessions were evaluated in a field trial and a core collection was developed. This collection was then evaluated in seed production and turfgrass trials and those possessing both good seed yield without field burning and turfgrass quality were identified and planted in a space-plant nursery at Pullman, WA. The eight PI accessions and two commercial cultivars checks 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. 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. Selection for seed yield components had a variable response and seed yield was more dependent on accession. 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 plots. Both had fair turfgrass quality, whereas PI 371775, selection seeds panicle-1 , had good turfgrass quality while maintaining good seed yield with irrigation. These selections have been harvested for seed increase (2012-2014) and germplasm probably will be released by 2015.