Cover Crop Cultivar, Species, and Functional Diversity is Reflected in Variable Root Exudation Composition

Cover cropping has emerged as a sustainable alternative
to traditional
crop rotational practices, yet the effects of variable root exudation
from cover crop species and cultivars within species remains unclear.
Here, we assess the chemical heterogeneity of root exudates from 16
commonly used cover crop species as well as 3 distinct cultivars of
hairy vetch. Plants were grown hydroponically and analyzed via nontargeted
gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem
mass spectrometry (LC-MS/MS), and targeted LC-MS/MS to evaluate patterns
in root exudate composition across species and functional plant type.
Overall, root exudation profiles are heterogeneous across crop species
and cultivars. Species within legumes stand out as a unique functional
group of plants capable of producing distinct chemical environments
rich with complex secondary metabolites, such as triterpenoid saponins
(soyasaponins), isoflavonoids, and flavonoids.