Topical selection in rangeland plants that have multi-purpose use is one of the major programs of natural resources departments. Therefore, working on medicinal plants that can grow in sloping areas and have a high soil protection capacity can be a strategic and practical issue for you.
Examining the genotypes of a plant in different climatic conditions in terms of growth traits or the number of active ingredients can be a practical topic for you.
Habitat suitability of medicinal plants is an interesting topic as well. In some cases, some medicinal plants grow best in higher elevation [as their natural habitat], and doing in situ cultivation (lower elevation) may be a good experiment to support future conservation programs to be placed in green houses / botanic gardens.
How about looking at synergistic interactions between phytochemicals in whole plant medicines? This is an area that is much mentioned in scientific papers regarding mechanisms of actions of medicinal plants, but could really do wth more research.