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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #413877
Research Project: Expanding Resiliency and Utility of Alfalfa in Agroecosystems

Location: Plant Science Research

Title: Plasticity in root attributes and belowground interactions between a perennial legume and a grass companion

Author
item NOSSHI, MAGED - Oak Ridge Institute For Science And Education (ORISE)
item Gamble, Joshua
item RUSSELLE, MICHAEL - Retired ARS Employee
item Samac, Deborah - Debby

Submitted to: Ecological Society of America (ESA)
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2024
Publication Date: 8/5/2024
Citation: Nosshi, M., Gamble, J.D., Russelle, M., Samac, D.A. 2024. Plasticity in root attributes and belowground interactions between a perennial legume and a grass companion. Ecological Society of America, August 4-9, 2024, Long Beach, California.

Interpretive Summary:

Technical Abstract: Fine roots can account for more than half of ecosystem net primary production, and the decomposition of fine roots can return nitrogen to the soil in amounts equal to or exceeding that from litter fall. Given that little retrantranslocation of nutrients precedes root senescence and decay, fine root turnover is an important pool of potentially mineralizable soil nitrogen. Among the most prolific nitrogen fixing plants, the perennial legume Medicago sativa (alfalfa) accrues more nitrogen from the atmosphere than most legumes. However, it does not share. Intercropping trials show that while alfalfa can more than double the amount of accumulated nitrogen, much less of this pool is shared with the companion plants. Among populations of alfalfa selected for contrasting root attributes, including different allocation to fine roots, we compare nitrogen transfer among three alfalfa populations, growing in mixtures with different perennial grasses in field trials. Understanding traits as the joint result of both genotype and environment, we compare differences among alfalfa populations in fine root production across contrasting sites. Finally, using a greenhouse experiment, we determine links between root attributes on nodulation and the percent of nitrogen derived from the atmosphere, to ultimately determine differences in rates of N2 fixation across four alfalfa populations. Preliminary data from the greenhouse experiment suggests that alfalfa with more a branched root morphology supported more nodules than alfalfa with a tap root morphology. Cross site comparison of fine root allocation for first year alfalfa suggest greater production of fine roots in the sandy loam (1.4% OM content site) than the silty loam site (3.7% OM).