Influence of light intensity on gas exchange, herbage yield and andrographolide content in Andrographis paniculata (Nees.)

摘要

The medicinal herb Andrographis paniculata containing a bitter principle andrographolide is widely used in indigenous system of medicines for treatment of various ailments in south Asian countries including India. It is found to grow as an understoryin its natural habitats. With a view to understand the role of shade on herbage yield, a two-year field study was conducted on sandy loam soil. The crop was grown under 25,50,70 and 100% incident photosynthetic photon flux density (PFD) by providing artificial shade nets and observations on plant height, fresh and dry weight of leaf, stem and total plant along with leaf gas exchange parameters. Significant differences were observed for all growth characters between open and shaded plants. Leaf photosynthesis increased from 11.56 to 19.70 mmol nrV as PFD increased from 25 to 100% and herbage yield increased from 226.70 to 379.45 g. Andrographolide content was not consistent under different PFD levels and highly influenced by the weather parameters. Since the total herbage and andrographolide yield was the highest under open light condition, it was concluded that A. paniculata is suitable for open cultivation.