Kentucky Bluegrass for 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 severely restricted in Idaho and Oregon.  The objective of the 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 and seed production plots (irrigated and non-irrigated) in 2007 at Pullman, WA.  The turfgrass trial was evaluated monthly according to NTEP (National Turfgrass Evaluation Program) protocol to determine turfgrass quality.  Seed production plots were harvested (2008 to 2011) and seed yield was determined (2011 data presented).  Results for 2011 (4^th harvest) indicated that selection for seed yield components had a variable response and Kentucky bluegrass seed yield was primarily dependent on accession.  Accession PI 368241 showed the best promise of being able to provide long-term turfgrass quality and seed yield under non-burn management in both non-irrigated and irrigated seed production.  One selection within Kenblue, seed head^-1, had good turfgrass quality and seed yield.  These studies will be followed during 2012 to determine if high seed yields are sustainable.