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

Abstract

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‐field 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 field stands and that a long heading to anthesis period promotes seeds per panicle and seed yield.

Seed production of 'Mombasa' grass subjected to different closing cut dates and nitrogen rates

“…The model for the ASY and PSY analyses followed Johnson et al (2010), as follows: ASY (kg ha -1 ) = (one thousand apparent seed weight) x (apparent seeds per panicle) x (PTN); and PSY = (one thousand pure seed weight) x (pure seeds per panicle) x (PTN).…”

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

“…These accessions plus 17 commercial cultivars were evaluated for several years (Johnson et al, 2003) and eight PI accessions (plus two commercial check cultivars, "Kenblue" and "Midnight") representing germplasm that has good seed yield without field burning while maintaining turfgrass quality were identified. For these 10 selections, seed yield parameters were evaluated over a 2-yr period and individual plants were reselected within each accession, or check, with the highest seed weight, highest seed panicle -1 , highest panicles area -1 , and highest seed yield (Johnson et al, 2010). These 40 selections plus a base population of seed from the USDA/ARS collection were planted in turf plots in 2006 and non-irrigated and irrigated seed production plots in 2007 at Pullman, WA (Dodson, 2008).…”

“…Eight PI accessions and two check cultivars ("Kenblue" and "Midnight"), representing germplasm that had good seed yield without field burning while maintaining turfgrass quality in turf trials, were evaluated over a 2-yr period in a space plant nursery during 2002 and 2003 (Johnson et al, 2010). Individual plants were reselected within each accession, or check, with the highest seed weight, highest seed panicle -1 , highest panicles area -1 , and highest seed yield.…”

“…Individual plants were reselected within each accession, or check, with the highest seed weight, highest seed panicle -1 , highest panicles area -1 , and highest seed yield. Variation between and within accessions was identified (Johnson et al, 2010), so the potential exists for plant selection and enhancement.…”

“…To address this issue, we initiated a program to identify Kentucky bluegrass germplasm that would have sustainable seed yield without field burning. In a multi-year study we evaluated the USDA/ARS Poa pratensis L. collection and developed a core collection (Nelson, 1996), identified germplasm that has improved seed production without open-field burning of post-harvest residue (Johnson et al, 2003), reselected within that germplasm (Johnson et al, 2010), and established turfgrass and seed production trials (Dodson, 2008) that have been evaluated over several years (Johnston et al, 2012). Three selections are currently in seed increase (Johnston et al, 2014) and potentially germplasm will be released by 2015 for commercial cultivation.…”