William J. Johnston1, Richard C. Johnson2, Charles T. Golob1, Mathew C. Nelson3, Karine Pare1, and Kathleen Dodson1. (1) Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, (2) PO Box 646402, USDA-ARS, USDA ARS, Washington State Univ., 59 Johnson Hall, Pullman, WA 99164-6402, (3) United States Golf Association Greens Section, Twin Falls, ID 83303
A ban on burning of post-harvest grass seed residue has been implemented in Washington and Idaho and restrictions are in place in Oregon, USA. Without residue burning, Kentucky bluegrass (Poa pratensis L.) seed yield decreases over time. Growers have implemented yearly mechanical residue removal (raking and baling) and shorter rotations to maintain adequate seed yield; however, this practice is economically less viable to growers and is potentially harmful to the environment. The goal of this study is to develop turf-type bluegrasses that will maintain seed yield over several years without post-harvest burning. This long-term study began in 1994 at Pullman, WA with the evaluation of 228 Plant Introduction (PI) accessions from the USDA-ARS Kentucky bluegrass germplasm collection and the development of a core collection based on 17 agronomic characteristics using Ward's cluster analysis. In a 3-year residue management and turfgrass quality study of the core, PI accessions that had both high seed yield without burning and good turf quality were identified. This germplasm underwent further selection for two years in a space-plant nursery to identify within accession variation. Seed was obtained from four plants of each accession with the highest seed yield, seed weight, seed per panicle, and panicles per unit area. Seed from the original population (USDA-ARS germplasm collection) were also included. Seed were grown in flats in a greenhouse and plants were transplanted into a seed increase nursery in September 2004, at Central Ferry, WA. This material (eight accessions and two commercial cultivars x five selection parameters x 100 plants per parameter) was harvested June 2006 and is currently being evaluated in on-farm seed production and turfgrass trials at several locations in eastern Washington. Ultimately, turf-type Kentucky bluegrasses that can be grown for several years without burning will be released.