|Lamb, Joann - ARS EMPLOYEE|
|Barnes, Donald - FORMER ARS EMPLOYEE|
|Henjum, Keith - UNIVERSITY OF MINNESOTA|
Submitted to: Alfalfa Improvement Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 17, 1996
Publication Date: N/A
Technical Abstract: A major limitation to better management of symbiotically fixed N from alfalfa is the lack of varieties with specific characteristics that influence the N cycle. Characteristics of interest would include root morphology, root elongation rate, nitrogen uptake, and biological nitrogen fixation. The objectives of this study were (1) to evaluate experimental alfalfa germplasms that were selected for many versus few branched roots and low versus high amounts of fibrous roots, and (2) to determine the impact of selection for root traits forage yield, dormancy, and disease resistance. Selected and unselected populations were established in two experiments at both Becker and Rosemount, MN, in May 1994. One experiment at each location was dug in October 1994 and the other in October 1995. All plots were evaluated for taproot diameter (measured in mm), number of secondary roots (scored, 1 = few, 5 = many), and amount of fibrous roots (scored, 1 = few, 5 = many). High fibrous and branched selections had significantly more fibrous and branched roots and greater herbage yield than the low fibrous and few branched root selections. Disease resistance and dormancy rating were unaffected by selection for root traits.