Genotype and Environment Affect Rhizome Growth of Birdsfoot Trefoil.

Rhizome production has been transferred from wild germplasm of Lotus corniculatus L. (broadleafed birdsfoot trefoil) into domesticated germplasm to produce `ARS-2620' and `ARS-2424' (a L. corniculatus × L. uliginosus hybrid). The objective of this study was to determine if field environments in the United States differing in latitude affect rhizome expression in genotypes of ARS-2620 and ARS-2424. Ramets of rhizomatous genotypes of ARS-2620 and ARS-2424, and nonrhizomatous `Norcen' were planted at seven locations in late July and August 1999. At five locations in 2000 and 2001, dormant plants were hand-dug in late autumn or winter. Traits measured were mean crown-plus-root mass, crown circumference, and percentage survival for all entries, and rhizome mass for the two rhizomatous entries. Significant (P ≤ 0.001) location X genotype effects were observed for all traits in 2000, hut only for percentage survival in 2001. In 2001, the effect of locations was significant for all traits (P ≤ 0.001), but genotype effects were significant (P ≤ 0.001) only for crown circumference and percentage survival. The rhizomatous entries were larger in circumference and had a greater crown-plus-root mass than Noreen. Rhizomes appeared to be beneficial to plant survival and plant growth, but rhizomes did not assure performance or survival, as we did not identify a genotype that performed well across locations. High plant mortality and extensive tissue necrosis caused by root and crown-rot complex reduced overall plant performance and rhizome expression and masked the interpretive value of the data from the five locations. Plants grown in Logan, UT, were notable for their large size and rhizome production relative to the other locations, and as having advantageous, but undefined, environmental conditions beneficial to the performance of rhizomatous birdsfoot trefoil. [ABSTRACT FROM AUTHOR]