Seed Yield, Development, and Variation in Diverse Poa pratensis Accessions

Post-harvest residue removal is critical for high seed production of Kentucky bluegrass (Poa pratensis L.). Previous work showed some accessions have little yield reduction with mechanical removal of post-harvest residue compared with the controversial practice of open-fi eld burning. Using 10 of these accessions, our objectives were (i) to relate seed yield and yield components in spaced plants to yield in row-seeded plots, (ii) to link yield to growth and development factors, and (iii) to determine variation for seed production factors among accessions. Seed yield, seeds per panicle, panicle number, weight per seed, heading, anthesis, and harvest dates showed strong accession differences on spaced plants in 2002 and 2003. Yields in row-seeded plots from 1998 and 1999 data were consistently correlated with yield per plant per area in spaced plants in 2002 (r = 0.75, P < 0.05) and 2003 (r = 0.90, P < 0.01). Turf quality was negatively correlated with yield per plant per area in 2002 and 2003 but was not consistently correlated with yield components. Days from heading to anthesis consistently correlated with yield per plant per area in 2002 (r = 0.81, P < 0.01) and 2003 (r = 0.85, P < 0.01). Variation for seed yield and yield components was observed within accessions both years and differed among accessions. The results show that seed yield per plant per area in spaced plants may be a useful predictor of yield in fi eld stands and that a long heading to anthesis period promotes seeds per panicle and seed yield. R.C. Johnson, USDA–ARS, Box 646402, Washington State Univ., Pullman, WA 99164; W.J. Johnston and C. Golob, Washington State Univ., Box 646420, Pullman, WA 99164; F.B. Bertoli, Monsanto Company, Milan, Italy. Mention of product names does not represent and endorsement of any product or company but is given only to clarify the methodology; other products may be equally eff ective. Partial fund