CONVERGENT DIVERGENT SELECTION FOR SEED PRODUCTION AND FORAGE TRAITS IN ORCHARDGRASS .2. 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 for age-producing regions are unable to effectively select for Pacific Nor thwest seed yield by direct selection in their environment. This study was undertaken to determine if selection for broad adaptation for see d yield within forage-producing regions could maintain commercially ad equate seed production when grown in the U.S. Pacific Northwest. Two c ycles of convergent-divergent (C/D) selection were conducted and the r esulting 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 se lection criterion for seed production. Except for the WO11 population, PSW remained unchanged when the selected and original populations wer e grown in Oregon. Both C/D and local selection methods resulted in de creased PSW in WO11. However, total seed yield (TSY) increased 163 aci d 111 kg ha(-1) cycle(-1) for the MO2 and WO11 populations, respective ly, 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 Or egon, Total seed yield of I79DT and PLS4 was not changed by either C/D or local selection. A shift toward later maturity occurred in three o f the four populations as a result of either CID or local selection. A population selected from WO11 was both as late maturing and as high y ielding as the latest-maturing and highest-yielding cultivars tested. Multiple-location selection, such as C/D selection, can effectively ac cumulate genes for broad adaptation making it possible to achieve high seed yields concomitantly with later maturity.