Izham, A. , Alireza, N., Syahida, A., Radziah, O. and Ghizan, S.
Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
Sabah snake grass (Clinacanthus nutans) is one of the potential medicinal herbs to be developed and promoted by the Herbal Development Office of the Malaysian Ministry of Agriculture and Agro-based Industry. Growth, physiological responses and changes in antioxidant activity in C. nutans were measured when treated with five fertilizer N levels viz. 0, 100, 150, 200 kg/ha and chicken manure at 8 ton/ha. Plant height (80 cm) and number of branches (5.3/plant) were highest at 150 kgN/ha. There was no significant difference in these two parameters between 150 and 200 kgN/ha treatments. However leaf area (1423.3 cm2), photosynthetic rate (14.44 μmol CO2/m2/s) and stomatal conductance (0.17 mol/m2/s) were significantly higher at 150 kgN/ha application over the other tested treatments. These increase subsequently contributed to a higher fresh (130 g/plant) and dry (30.88 g/plant) weights of the plant at 150 kgN/ha treatment. Antioxidant activity was determined by Ferric Reducing Antioxidant Potential (FRAP) and 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assays. FRAP value and DPPH scavenging capacity were 625.44 μmol Fe(II)/g dry weight and 57.86% respectively from leaf extracts of C. nutans plants supplied with 150 kgN/ha. The study demonstrated the potential of optimizing the supply of nitrogen to increase the primary metabolites and antioxidant activity in C. nutans.
Kewords: Clinacanthus nutans, antioxidant activity, medicinal herb, nitrogen fertilization.