Honors Theses and Capstones

Date of Award

Spring 2023

Project Type

Senior Honors Thesis

College or School



Department of Biological Sciences

Program or Major


Degree Name

Bachelor of Science

First Advisor

Anissa Poleatewich

Second Advisor

Haley Nolen


Abiotic stressors, such as nutrient and drought stress, are a leading cause of crop yield reduction. Some bacteria and fungi are able to promote plant growth and increase stress tolerance by increasing nutrient availability through nitrogen fixation or phosphate solubilization, outcompeting pathogens, productions of volatile organic compounds (VOCs), reducing plant stress, and inducing induced systemic resistance (ISR), and thus serve as a valuable component of agricultural ecosystems to reduce dependency on chemical fertilizers. Chenopodium quinoa is a crop native to South America that has been gaining popularity in the United States because of its nutritive properties and resistance to drought and salinity. Quinoa has potential for cultivation in New England but has trouble growing in the region due to biotic and abiotic challenges however, wild Chenopodium species thrive in the region. Chenopodium ficifolium is a New England native relative of quinoa that thrives in the region and is considered to be a possible plant-microbe interactions model for quinoa. Commercially developed microbial products such as biostimulants present a possible solution to enhance quinoa growth in New England by increasing the tolerance and quality of quinoa. It has been noted that different 5 genotypes of plant hosts will recruit different microbes that can benefit them under stress. Even the same microbe can have various levels of growth-promotion due to the ecotype of the host, but there is little research on ecotype selectivity on Chenopodium species. In this work, we performed a controlled environment growth room study to evaluate the plant growth response of two Chenopodium ficifolium ecotypes from Portsmouth, NH (P2) and Quebec City, Quebec, Canada (QC4) to a commercial biostimulant (active ingredient Bacillus velezensis NCIMB 30322. The objective of this study was to evaluate the effect of a commercial biostimulant and nutrient-depleted conditions on the growth of two ecotypes of C. ficifolium. This is the first study to assess how a North American commercial biostimulant can affect the growth of Chenopodium spp. We hypothesized that the application of B. velezensis would promote growth and photosynthetic activity of two C. ficifolium ecotypes and that the two ecotypes would respond differently to the presence of the biostimulant under nutrient-depleted conditions. Our results show that B. velezensis NCIMB 30322 did not have a significant impact on biomass and chlorophyll content of either ecotype compared to the control but that the ecotypes do significantly differ from each other. Considering these results and the results of previous work with B. velezensis and quinoa, it is not clear if C. ficifolium and C. quinoa respond to B. velezensis in the same way, in order to support C. ficifolium as a plant-microbe interactions model for C. quinoa. More work is needed to directly compare growth of C. ficifolium, C. quinoa, and other Chenopodium species in response to the application of biostimulants.

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