Effect of watering interval and planting media composition on growth, chlorophyll, and flavonoid content of sambiloto (<i>Andrographis paniculata</i> Nees.)

Sambiloto (Andrographis paniculata Ness.) is a plant rich in natural antioxidants (flavonoid and andrographolides) that had great importance to medicine industry.Drought stress affects the content of secondary metabolites played vital roles as antioxidants.Improving the quality of sambiloto by elevating the flavonoid, can be achieved through drought stress.Moreover, drought stress also affects growth.By utilising marginal lands such as ultisols to cultivate sambiloto, soil amendments is needed to improve fertility.This study aims to investigate the effect of drought stress by various of watering intervals and the composition of planting media on the growth, chlorophyll content, and flavonoids in sambiloto plants.The experimental design was a factorial randomized block design with two factors and three replications.The first factor was the watering time interval, namely watering once every 2 days, watering once every 3 days, watering once every 4 days, and watering once every 5 days.The second factor was the composition of the planting media, namely ultisol soil + chicken manure (1:1/v:v), ultisol soil + rice husk charcoal + chicken manure (2:1:1/v:v:v), ultisol soil + rice husk charcoal + chicken manure (1:1:1/v:v:v), and ultisol soil + rice husk charcoal + chicken manure (1:2:2/v:v:v).The results showed that the combination of watering intervals once every 2 days with the media composition of ultisol soil + rice husk charcoal + chicken manure (1:2:2/v:v:v) or the media composition of ultisol soil + rice husk charcoal + chicken manure (1:1:1/v:v:v) produced a higher shoot root ratio and fresh weight of the inflorescence compared to other treatments.This study suggest that watering interval once every 5 days with the composition of ultisol soil media + rice husk charcoal + chicken manure (1:2:2/v:v:v) have the potential to optimize the flavonoid contents of sambiloto.