Elucidating rhizobacterial response to autoclave disruption and crop introduction within three distinct agricultural soils
Date
2020
Authors
DiLegge, Michael J., author
Vivanco, Jorge M., advisor
Manter, Daniel K., committee member
Weir, Tiffany L., committee member
Minas, Ioannis S., committee member
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Abstract
Management practices can affect the soil health properties of an agroecosystem, in turn effecting the resident soil microbial community. Insights toward how managerial practices effect soil microbial rearrangements are steadily being uncovered with next generation sequencing applications. This thesis covers research investigating how soilborne and plant-rhizospheric bacteria from three differential agricultural management systems are affected by applied disruption followed by the introduction of new plants to their sites. Two independent greenhouse experiments were conducted to evaluate plant-mediated bacterial rearrangements in soil following autoclave disruption. The first study utilized two soil types from a perennial peach orchard system experiencing negative effects of orchard replanting disease. Soils were sampled from a replanting disease (RD) site and a non-replanting disease (non-RD) block. Replanting disease soils were autoclaved; and peach, corn and tomato plants were grown in both autoclaved and unautoclaved RD soils, as well as non-RD soils. Bacterial phyla and their predicted functional genomics were assessed after autoclave disruption and plant growth. The second experiment was an expansion of the former, utilizing autoclave disruption and the same perennial RD soil from the former study, but with the addition of conventional and organic annual agroecosystem soils. In this experiment four crops of differing plant families (corn, beet, tomato and lettuce) were introduced to examine how soil bacterial rearrangements may be influenced by distinct crop-presence after autoclave disruption. Results showed that autoclave disruption increased plant biomass. Interestingly, the type of crop plant introduced as well as the agroecosystem soil type drove differential bacterial responses and rearrangements. These data demonstrate that both agricultural ecosystem management, paired with the family of plants grown in these ecosystems, strongly impact soil bacterial availability and rearrangement in the rhizosphere. Additionally, in agricultural sites experiencing severe long-term dysbiosis, an autoclave disruption in pair with the rotation of monocultured crops may prompt the colonization of a healthier rhizomicrobiome.
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Subject
agroecosystem
PGPRs
16s sequencing
soil health
disruption