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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #382891

Research Project: Trait Discovery, Genetics, and Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research

Title: Carrot genotypes differentially alter soil microbial communities and scavenge nitrogen from organic materials in soil

item TRIVINO, NARDA - Purdue University
item FILLEY, TIMOTHY - Purdue University
item CAMBERATO, JAMES - Purdue University
item COLLEY, MICAELA - Organic Seed Alliance
item Simon, Philipp
item HOAGLAND, LORI - Purdue University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2023
Publication Date: 2/9/2023
Citation: Trivino, N., Rodriguez-Sanchez, A., Filley, T., Camberato, J., Colley, M., Simon, P.W., Hoagland, L. 2023. Carrot genotypes differentially alter soil microbial communities and scavenge nitrogen from organic materials in soil. Frontiers in Plant Science. Article (the author) 2023.

Interpretive Summary: Chemical nitrogen fertilizer is commonly used for crop production, but it is not efficiently taken up by growing plants, and is not used in organic management systems. Microbes in the soil decompose organic sources of nitrogen that plants can take up and use to support growth, and it has been observed that genetic variation among plants of a given crop can influence that decomposition process. Consequently, not all cultivars of a given crop grow equally well in a given field because of this crop plant variation in accessing nitrogen from organic nitrogen sources such as manures and plant tissue residues. In this study, a small collection of diverse carrots was grown in a standard soil mix with only organic sources of nitrogen, and a range of variation in plant growth was observed. Two USDA inbred carrot lines stimulated the release of more nitrogen, and consequently faster growth, than did three other carrot varieties. The soil microbes that were found in the root zone of these diverse carrots were analyzed, and a different population of microbes was found in the faster growing carrots than in the slower-growing carrots. This research suggests that it may be possible for vegetable breeders to develop carrot varieties that are more efficient in stimulating release of nitrogen from organic sources in the soil, and this research is of interest to carrot growers and researchers, soil scientists, microbiologists, and vegetable breeders.

Technical Abstract: Farmers need alternative approaches to manage nitrogen (N) that simultaneously meet crop needs while reducing loss to the environment. Identifying crop genotypes that promote positive priming of organic fertility sources in one approach that could help to address this challenge. Carrot is known as an N-scavenging crop making it an ideal model crop to investigate this phenomenon. The goals of this study were to: 1) determine whether carrot genotypes differ in their potential to facilitate organic matter decomposition to help scavenge N in soil, and 2) identify microbial taxa and predict functional genes that are stimulated by carrot roots and thus could play a role in these processes. To accomplish these goals, we grew five carrot genotypes in a nutrient-poor soil amended with 15N-enriched corn residue, tracked changes in carbon (C) and N pools, quantified microbial activity and bacterial community composition, and predicted the potential expression of microbial genes involved in soil C and N cycles. Results indicate that there are differences among carrot genotypes in their potential to stimulate decomposition of organic materials and scavenge N from organic materials. The experimental genotypes 8503 and 3999 had the greatest capacity to scavenge N from organic substrates and thus have the greatest potential to optimize production in systems that rely on organic fertilizers. We also observed distinct differences in soil bacterial communities associated with these genotypes that could be related to their potential to cycle C and N. For example, bacteria from the families Micromonosporaceae, Chromatiaceae, and Rhodospirillaceae were enriched in the soils of carrot genotypes that were most effective in scavenging N and this was correlated with greater potential expression of microbial genes responsible for ß-glucosidase and nitrification activity. Other genotypes were enriched in bacteria from the family Oxalobacteraceae, which have been observed in disease suppressive soils and thus could potentially aid in disease resistance. Results of this study highlight the importance of understanding relationships between soil management practices and crop genotypes to optimize crop productivity in agricultural systems while protecting the environment.