Abstract
American chestnut was a dominant eastern tree species before its functional extinction by the chestnut blight (Cryphonectria parastica). This research evaluated the performance of Darling 54 transgenic American chestnuts in two experimental plots to assess their restoration potential. Chapter 2 investigated growth, morphology, and respiration in the context of non-transgenic chestnut types, finding that transgenic trees maintained positive crown form, despite growth reductions and occasionally increased respiration relative to wildtype counterparts. Chapter 3 assessed the growth and physiological responses of co-cultivated grapevines and hybrid transgenic chestnuts under varying co-cultivation densities. While both crops benefited under the lowest density, grapevines showed reduced performance at higher densities, suggesting a shift from facilitation to competition. Growth patterns were not linked to photosynthetic or water use metrics, indicating legacy effects of prior seasons. Overall, these findings further characterize presently under-examined American chestnut physiology and support the viability of Darling 54 chestnuts as restoration trees.