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The symbiotic relationship between legumes and their respective rhizobia is a complicated and delicate balance. The rhizobia live in the host plant by forming a nodule through the process of nodulation. The symbiotic relationship involves an efficient and productive method of biological nitrogen fixation (BNF) to help the plant survive in potentially stressful environmental situations. Some common stresses for plants, and legumes in particular, include osmotic and heavy metal stresses that either naturally occur from the breakdown of local mineral sources or from the artificial addition of a stress to the environment caused by humans. In this study, the legume plant Medicago sativa (alfalfa) and Sinorhizobium meliloti bacteria will be examined in stress conditions. This research will be examining the ability of M. sativa to germinate in stress conditions involving elevated concentration of salt, sucrose, copper, and zinc. Additionally, the relationship between the host plant alfalfa and S. meliloti, two of its mutants (MocE and MocD), or a direct source of nitrogen will be examined in relation to the plant’s ability to combat stressed environmental conditions over a 21-day period.
Mears, Claire, "The impact of S. meliloti or other sources of nitrogen on alfalfa growth under osmotic or heavy metal stress" (2018). Honors Theses. 3065.