Poster

         Symbioses: Plant, Animal, and Microbe Interactions

Resilience Through Complementarity: Assessing the Compatibility of Corn, Bean, and Squash Root Architecture, Exudates, and Soil Associated Microbes in the Three Sisters Polyculture

Presenting Author
Bailey Kretzler
Description
Resilient agroecosystems used in smallholder production support global food security and producer livelihoods. Many of these systems, including the three sisters polyculture, display remarkable resilience to abiotic and biotic stressors. The three sisters is a polyculture of corn, bean, and squash used by indigenous people in North America that offers a lower input alternative to high input conventional agriculture. Previous studies show that corn, bean, and squash adopt complimentary root architectures when grown in polycultures. Such changes in root architecture are shown to impact root exudate profiles and soil microbial identity and function. Thus, differences in plant root traits and soil microbial characteristics may support the three sisters’ resilience. However, the plant-soil-microbe interactions driving the three sisters ability to maintain stable yields under stress remain understudied. It is important to identify the plant root traits and soil microbial characteristics enabling the polyculture’s ability to endure and rebound from stress in order to design more resilient agroecosystems. We use a combination of growth chamber experiments and common gardens to understand how crop root architecture, exudates profiles, and soil microbial communities differ between polycultures and monocultures of corn, bean, and squash.  In growth chamber experiments, corn and beans were grown in Hoagland’s media solidified with gellan gum to determine the impact of growth in co-culture on root exudates and architecture. Plants were grown for 10 days alone, with each other, and with themselves. 3-D root architecture was determined by taking picture of plant root systems on days 3, 5, 7, and 10 using the Topp lab gel imaging platform. At the end of the growth period, media was collected from interacting and isolated root tips to assess root exudate profiles. In complement to this work, common gardens will be established in Maine and Vermont to assess the additive impact of corn, bean, and squash on soil microbial characteristics. Crops will be grown in monoculture, biculture, and triculture. We will collect rhizosphere and bulk soil samples and root and shoot material to determine each crops impact on soil microbial communities and crop above and below ground complementarity. Our research highlights how the three sisters polyculture can support healthy agroecosystem function. Plant traits identified in our research as supporting resilience can be used in indigenous breeding efforts to promote food security while preserving cultural relevance. Unpacking the complex plant-soil-microbe dynamics of the three sisters ultimately enables us to design and execute more resilient agroecosystems and sustainable food production.