Previous crop and rotation history effects on corn health and associated microbiome

Authors: Benitez Ponce, Maria; Osborne, Shannon; Lehman, R - Michael

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2017
Publication Date: 11/16/2017
Citation: Benitez Ponce, M.S., Osborne, S.L., Lehman, R.M. 2017. Previous crop and rotation history effects on corn health and associated microbiome. Scientific Reports. 7:15709. https://doi.org/10.1038/s41598-017-15955-9.
DOI: https://doi.org/10.1038/s41598-017-15955-9

Interpretive Summary: The benefits of crop rotation have long-been appreciated; however, the specific mechanisms that confer these benefits (increased soil fertility, enhanced pest and pathogen resistance) are not understood. We hypothesized that these benefits are related to selection of different soil microorganisms that inhabit the plant rhizosphere, which is a zone of enhanced microbial diversity and activity in, on, and adjacent to the plant roots. We evaluated the effect of preceding crop (sunflower, pea, soybean, or corn) on subsequent growth of corn seedlings and the composition of microbial communities that inhabit their rhizosphere. Using soils from each of the four crops preceding corn in field plots, we raised corn seedlings in the greenhouse and evaluated their vigor and composition, and characterized the associated rhizosphere microbial communities. Corn seedlings grown in soils from sunflower and pea showed greater vigor compared to after soybean and corn. When corn seedlings were stressed by inoculation with Fusarium graminearum, root damage was significantly lower in soils from sunflower. Stressing the corn seedlings with western corn rootworm resulted in selection for specific microbial taxa. In general, inoculation with F. graminearum affected known fungal endophytes including Trichoderma and Endogone. In comparison to the biological stressors, rotation sequence had a greater effect on rhizosphere microbial communities, with larger effects observed for fungi compared to bacteria. The relative abundance of arbuscular mycorrhizal fungi was significantly higher in soils from sunflower and corn treatments. Defining the mechanisms responsible for crop rotation effects will promote selection and adoption of favorable crop rotation sequences.

Technical Abstract: To evaluate crop rotation effects on corn seedling performance and its associated microbiome, corn plants were grown in the greenhouse in soils collected from four different crops (corn, pea, soybean and sunflower). Each crop preceded corn in replicated field trials with differing four-year rotations. A stressor was introduced by soil infestation with western corn root worm (WCR) or inoculation with Fusarium graminearum. Under non-infested conditions, corn seedlings grown in soils from sunflower and pea showed greater vigor. Stress with WCR or F. graminearum resulted in significant root damage. WCR root damage was equivalent for seedlings grown in soils from the different rotation treatments; whereas F. graminearum root damage was significantly lower in corn grown in soils preceded by sunflower. Infestation with WCR affected specific microbial taxa (Acinetobacter, Smaragdicoccus, Aeromicrobium, Actinomucor). F. graminearum inoculation affected known fungal endophytes including Trichoderma and Endogone. In comparison to the biological stressors, rotation sequence had a greater effect on rhizosphere microbial communities, with larger effects observed for fungi compared to bacteria. The relative abundance of Glomeromycota was significantly higher in soils from sunflower and corn treatments. Defining the mechanisms responsible for crop rotation effects will promote selection and adoption of favorable crop rotation sequences.