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Oral: Pathogen Ecology


Long-term rotation history and previous crop effects on corn seedling health
M. BENITEZ (1), S. Osborne (2), M. Lehman (2) (1) USDA, Northe Central Agricultural Research Laboratory, U.S.A.; (2) USDA, North Central Agricultural Research Laboratory, U.S.A.

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Diverse rotations provide benefits to agroecosystems through changes in the soil environment. A long term experiment was established to study four different four-year rotation sequences in which the crop phase prior to corn was sampled. Soils from rotations ending with soybean, sunflower, corn and pea were tested for effects on subsequent corn in the greenhouse. Corn was grown in a soil mix containing 12% of rotation soil either infested with corn root worms (CRW) or inoculated with Fusarium graminearum. Seedlings were scored for root damage and shoot vigor, rhizosphere samples collected for microbiome analyses and remaining roots scanned for root measurements. Seedlings grown in soils from rotations ending with pea and sunflower had greater vigor regardless of CRW infestation. Seedlings grown in non-inoculated soils from pea rotation had shorter roots but greater root volume and diameter. Differences in germination time and vigor were stronger between Fusarium-inoculated and non-inoculated soils originating from pea rotations, compared to other rotations. The response to the rotation ending in pea is consistent with field observations where corn grown after pea requires less fertilizer. Analyses of the rhizosphere microbiome and seedling nutrient content, together with soil physico-chemical characteristics will provide insight on the mechanisms through which corn respond positively to rotation sequences incorporating pea.