Degree Type


Date of Award


Degree Name

Doctor of Philosophy




Superior seed-yielding ability of orchardgrass (Dactylis glomerata L.) synthetics is of considerable importance during the seed multiplication phases of cultivars released for commercial use. Objectives of this study were to: (1) evaluate orchardgrass breeding material for seed production in the Willamette Valley of Oregon, and near Ames, Iowa; (2) determine the degree to which seed yields in Iowa predict seed yields in Oregon; (3) determine the correlation between parent clones and polycross (PC) progenies for seed production and related traits in both states and between states; (4) determine traits which could be used in Iowa to select among clones or individual plants for satisfactory seed production in Oregon; and (5) study relationships between seed and forage traits. Clones, PC progenies, synthetics, and populations selected in Iowa for desirable forage characteristics were evaluated for seed yield and related traits near Corvallis, Oregon, and Ames, Iowa. In addition, the material in progeny seed yield tests was evaluated for forage production and quality near Ames, Iowa. All PC progenies, populations, and synthetics yielded significantly less seed than "Hallmark" and "Potomac" in Oregon; however, some PC progenies were similar in yield to "Sterling." Correlations between states for yield were nonsignificant or low for parent clones and their PC progenies. Other correlations between locations, however, indicated that selection among clones in Iowa for anthesis date, 100-seed weight, and fertility index would be effective in terms of changing Oregon clonal performance. Oregon progeny seed yield was significantly correlated in a positive manner with fertility index and 100-seed weight and in a negative manner with anthesis date and plant height of both clones and progenies in Iowa. Significant Iowa parent-Oregon progeny correlations were obtained for seed yield per panicle, panicle length, 100-seed weight, anthesis date, and plant height. Selection for Oregon progeny seed yield resulted in the greatest predicted genetic gain in Oregon seed yield, but selection among Iowa clones for early maturity and for a combination of early maturity, high seed yield per panicle, high fertility index, and high 100-seed weight by using the Smith-Hazel selection index gave predicted gains only 6 and 2% less, respectively, than those based on Oregon progeny seed yield. Although not significant, high Oregon progeny seed yield tended to be associated with high forage yield and low IVDMD, indicating some compromise would be necessary when breeding for both forage and seed traits in this material.



Digital Repository @ Iowa State University,

Copyright Owner

Roy Luedtke



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151 pages