Convergent-Divergent Selection for Seed Production and Forage Traits in Orchardgrass: II. Seed Yield Response in Oregon

More than 90% of U.S. production of orchardgrass (Dactylis glomerata L.) seed occurs in the U.S. Pacific Northwest. However, breeders in forage-producing regions are unable to effectively select for Pacific Northwest seed yield by direct selection in their environment. This study was undertaken to determine if selection for broad adaptation for seed yield within forage-producing regions could maintain commercially adequate seed production when grown in the U.S. Pacific Northwest. Two cycles of convergent-divergent (C/D) selection were conducted and the resulting populations were evaluated for 2 yr in Oregon. The experiment was a randomized complete block design with three replicates grown in the field on a Woodburn silt loam (fine silty, mixed, mesic Aquultic Argixeroll, on 0–3% slopes) soil. Panicle seed weight (PSW) was the selection criterion for seed production. Except for the WO11 population, PSW remained unchanged when the selected and original populations were grown in Oregon. Both C/D and local selection methods resulted in decreased PSW in WO11. However, total seed yield (TSY) increased 163 and 111 kg ha⁻¹ cycle⁻¹ for the MO2 and WO11 populations, respectively, from C/D selection. Populational buffering for TSY appeared to be present in these two populations because single-location selection at each of four sites was ineffective in increasing TSY as measured in Oregon. Total seed yield of 179DT and PLS4 was not changed by either C/D or local selection. A shift toward later maturity occurred in three of the four populations as a result of either C/D or local selection. A population selected from WO11 was both as late maturing and as high yielding as the latest-maturing and highest-yielding cultivars tested. Multiple-location selection, such as C/D selection, can effectively accumulate genes for broad adaptation making it possible to achieve high seed yields concomitantly with later maturity. Joint contribution of the USDA-ARS, of the Missouri, Oregon, and Wisconsin Agric. Exp. Stations, and of the NE-144 Regional Research Committee “Forage Crop Genetics and Breeding to Improve Yield and Quality.” Partial funding provided by the Oregon Orchardgrass Seed Producers Commission. Contribution No. 10,941 by the Oregon Agric. Exp. Stn., Corvallis, OR.