Effect of N and K doseson biomassand diterpenoid lactones production of Kalmegh (Andrographi spaniculata Nees.) in a semi-arid tropical climate

Kalmegh (Andrographis paniculata Nees.) is widely used as a medicinal herb in India and South-East Asian countries for treatment of liver disorder, bowel complaints, malaria, hypertension etc. Field experiments were conducted at CSIR-CIMAP, Research Centre, Bangalore, India to study the effect of doses of nitrogen (N) (0, 50, 100 and 150 kg ha⁻¹) and potash (K) (0, 41 and 82 kg ha⁻¹) on growth, biomass yield, nutrient uptake and diterpenoid lactones production. The results clearly revealed that application of 100 kg N ha⁻¹ and 82 kg K ha⁻¹ produced significantly higher herbage/biomass yield (6.1 t ha⁻¹) as compared to control (1.42 t ha⁻¹). The similar trends were observed in N and K uptake pattern. The application of 100 kg N ha⁻¹ and 82 kg K ha⁻¹ significantly increased the production of andrographolide (33.24 kg ha⁻¹) and neo-andrographolide (12.31 kg ha⁻¹) yield over control (16.02 and 4.06 kg ha⁻¹, respectively).