Effect of Fertilizer Application and Irrigation on Agronomic Characters of Andrographis paniculata (Burm. f.) Wall. ex Nees var. paniculata

Andrographis paniculata (Burm.f.) Wall. ex Nees var. paniculata belongs to the family Acanthaceae is an indigenous medicinal plant species in Sri Lanka. This study was designed to identify the effect of fertilizer and irrigation treatments on growth and agronomic characters of A. paniculata. The experiment was carried out in two agro ecological sites, the wet zone and the dry zone of Sri Lanka. Factorial combination of three fertilizer treatments: no fertilizer, organic fertilizer only (1kg per plot) and inorganic fertilizer only (N:P 80:40kg/ha) and two irrigation treatments (no irrigation and irrigation–twice a day) were used in a split-plot experimental design. Results revealed that the growth parameters measured showed significant variations between the two sites where the highest growth was reported in the wet zone with average dry weight per plant of 83g compared to 53g in the dry zone. According to the dry matter production, the optimum time for the harvesting of plants was identified as 3.5 – 4 months after planting. Data analysis showed significant differences in the total, shoot and leaf dry weight per plant of the different treatment levels. Root dry weights were not significant among treatment combinations. Results also revealed that the dry matter partitioning was significantly improved by the combined effect of both fertilizer and irrigation, but the magnitudes of impact are different for the two climatic zones. Application of organic fertilizer with irrigation was identified as the most suitable combination for cultivation of A. paniculata in both zones.