In: Phyton 53, Fasc. 2 (2013), S. 305–319, with 3 figures
Key words: Tropaeolum majus L., Tropaeolaceae, glucotropaeolin, phenological stage, sulfur, optimum harvest time.
Garden nasturtium (Tropaeolum majus L.) has been chosen as medicinal plant 2013 in Germany and its health effects are well described. In the presented study phenological characteristics of T. majus during the vegetation cycle have been assessed together with the determination of the glucotropaeolin (GT) content in different plant parts and GT yield (GT concentration × yield). A high concentration of this bio-active compound is a prerequisite for the commercial use of the plant.
Plant samples were taken weekly from field grown T. majus. Sulfur (S) was applied at two rates (0 and 100 kg ha–1 S) in order to enhance GT biosynthesis. The best GT yield was determined during main vegetative growth until flowering. The GT content decreased steeply in vegetative plant parts after main flowering, indicating transport of GT into flowers and seeds. Generally, growth of T. majus is characterized by a long flowering period where new flowers emerged side by side with developing and maturing seeds. S fertilization increased significantly the GT content in leaves at main vegetative growth by up to 23% and is next to harvest time an important measure to improve the product quality