Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/5/1997
Publication Date: N/A
Citation: Interpretive Summary: Orchardgrass is a highly nutritious grass grown for hay and in pastures, especially in mixtures with alfalfa used as forage for dairy cattle in the northeast and upper midwest regions of the USA. Late maturing cultivars of orchardgrass are desirable so they better match recommended harvest management of alfalfa. Unless seed can be efficiently produced, cultivars possessing even the most important forage traits will not be successful. The Oregon climate is ideal for orchardgrass seed production and over 90% of the USA orchardgrass seed is produced in the region. Genetic shift in grass cultivars with seed produced outside their region of forage production has been a concern in the grass seed industry for many years. To solve the problem, strict seed increase rules for seed certification with limited generations from breeder seed in designated seed producing areas were developed. Studies have suggested that orchardgrass germplasm must be evaluated for seed production potential in the region where seed will be grown. Convergent-divergent (C/D) selection is a method of selecting for broad adaptation in a germplasm pool. In part II of this series of 3 papers, we showed that a shift toward late maturity occurred in each of the 4 populations as a result of either C/D or local selection. Changes in total seed yield and maturity resulted in populations that were 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 in Oregon conditions concomitant with later maturity
Technical Abstract: Over 90% of USA production of orchardgrass (Dactylis glomerata L.) seed occurs in the Pacific Northwest. Breeders in forage producing regions, however, are unable to effectively select for 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 Pacific Northwest USA. Two cycles of convergent-divergent (C/D) selection were conducted in 4 forage producing states and the resulting populations were evaluated for 2 years in Oregon. Except for the WO11 population, panicle seed weight (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. Total seed yield (TSY), however, increased 163 and 111 kg/ha/cycle for the MO2 and WO11 populations, respectively. Populational buffering for TSY appeared to be present in these 2 populations because selection at WI contributed largely to the overall response from C/D selection. Total seed yield of 179DT and PLS4 was not changed by either C/D or local selection. A shift toward late maturity occurred in each of the 4 populations as a result of either C/D or local selection. Changes in TSY and maturity resulted in populations that were 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 concomitant with later maturity.