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

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

Automated summary

Cover cropping is a sustainable alternative to traditional crop rotation practices, but the impact of root exudation from different cover crop species and cultivars is still uncertain. This study used non-targeted gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), as well as targeted LC-MS/MS, to analyze the chemical composition of root exudates from 16 commonly used cover crop species and 3 distinct cultivars of hairy vetch. The results showed that root exudation profiles varied across crop species and cultivars, with legumes standing out as a unique group capable of producing diverse secondary metabolites.