Potential for Greenhouse Aeroponic Cultivation of Medicinal Root Crops

The therapeutic use of medicinal plants such as Echinacea, ginseng and St. John’s wort has gained widespread acceptance in North America in the last two decades. Aeroponic cultivation of medicinal plants have shown great potential for producing root yields that are cleaner, more uniform and faster maturing than can be obtained using conventional soil-based methods. Two pilot-scale commercial A-frame aeroponic systems were constructed at the Controlled Environment Agriculture Center (CEAC) using PVC plastic pipe and PVC-coated hex wire to support the plants. The entire surface of the A-frame structure was covered with a white-on-black co-extruded polyethylene film to contain the nutrient solution while preventing light from reaching the root zone. The bottom of the frame was lined with heavy plastic to collect the nutrient solution and return it to an external reservoir for reuse. Observation studies incorporating 96 Echinacea (Echinacea purpurea) and 30 burdock (Arctium lappa) plants were conducted beginning in December of 2000. The burdock demonstrated tremendous foliar and root production during their six months of growth. The harvested roots had desirable coloration with thick taproots and mature root bark. The Echinacea initially grew slowly, but exhibited accelerated growth by early March and were in full bloom by May. The fibrous roots of the Echinacea plants were harvested nine months after seeding, showing excellent coloration and growth. Considerable variation in size and yield was observed among plants, particularly in the Echinacea, which was likely due to significant genetic variation of the seed.