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Dissertation
Impacts of pea-canola intercropping and associated management practices on the soil microbiome
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2024
DOI:
https://doi.org/10.7273/000007175
Abstract
Intercropping has begun to captivate the interests of agronomists and microbial ecologists alike due to its promise to reduce the environmental impacts of our agricultural systems while maintaining high yields and improving profit margins. Specifically, legume non-legume intercropping systems show exceptional promise due to the unique relationship legumes share with nitrogen fixing bacteria known as rhizobia. The pea-canola (Pisum sativum-Brassica napus) intercropping system (peaola) is one such intercropping system. Consistently, it has been observed to show improved yields from monoculture within the same land area with minimal to no nitrogen fertilizer addition. Agronomists had long hypothesized that plant associated microorganisms were responsible for this observation, but work had not been done to show this. Therefore, the goal of our study was to determine how pea-canola intercropping, and its management practices impact the structure and predicted function of soil and rhizosphere microbial communities. We also aimed to determine if changes to nitrogen availability and uptake were changed with intercropping and across management practices with the potential to link these changes to the microbial community. To do so, we collected soil and rhizosphere samples from field grown peaola which tested the impacts of intercropping, variation in nitrogen fertilizer application, and variation in pea and canola seeding rates. We performed 16S rRNA sequencing to allow for characterization of the microbial community, and we analyzed the soil and leaf nitrogen content. Regardless of intercropping and management practices, we saw that plants ultimately determined the structure of their associated microbial communities, and subsequently their predicted function. Evidence from our analyses of soil and leaf nitrogen content revealed that generally variation in peaola management practices did not cause any significant changes. This is likely due to the plant facilitated changes we observed compensating for changes in nutrient availability based on nitrogen fertilizer application and plant-plant interactions. Future studies on intercropping systems should focus on characterizing changes in plant-plant interactions across management practices in addition to validating and further investigating the function of the microbial community.
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Details
- Title
- Impacts of pea-canola intercropping and associated management practices on the soil microbiome
- Creators
- Janice M. Parks
- Contributors
- Maren L Friesen (Chair)Stephen P Ficklin (Committee Member)Kiwamu Tanaka (Committee Member)Cara Haney (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Program in Molecular Plant Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 254
- Identifiers
- 99901195200701842
- Language
- English
- Resource Type
- Dissertation