Effects of water and nitrogen stresses on growth, phytochemicals and antioxidant of orthosiphon stamineus plant

Abiotic stresses particularly water stress and nutrient deficiency may elicit the biosynthesis pathway of herbal metabolites, where they are also useful to enhance the yield of herbal metabolites. Thus, this study was carried out to investigate the effects of soil water and nitrogen stresses on the...

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Format: Thesis
Language:English
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Online Access:http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78265/1/Page%201-24.pdf
http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78265/2/Full%20text.pdf
http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78265/3/Noorhaslina.pdf
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Summary:Abiotic stresses particularly water stress and nutrient deficiency may elicit the biosynthesis pathway of herbal metabolites, where they are also useful to enhance the yield of herbal metabolites. Thus, this study was carried out to investigate the effects of soil water and nitrogen stresses on the accumulation of herbal bioactive compounds. The primary experiment was to refine the methanol extraction conditions (methanol concentrations and times) in order to improve extract quality of O. stamineus. The leaf and stem were extracted in 0, 25, 50 and 100% methanol for 2, 4 and 8 hours at 400C. The results of total phenolic content and antioxidant capacity were increased when the leaf and stem extracted with 50% methanol but the time extraction did not influence the phenolics concentration and the antioxidant capacity. For the bioactive compunds concentration, the rosmarinic acid is the highest bioactive compounds as compared to 3’-hydroxy-5,6,7,4’-tetramethoxyflavone, sinensetin and eupatorin when extracted with 100% methanol for 4 hours. Another experiment was to investigate the effects of water stress at different levels and duration on bioactive concentration of O. stamineus leaf, stem and root. The water stress were set; high (25-35% of field capacity), moderate (45-65% of field capacity) and low (75-90% of field capacity). The water stress levels and stress duration main effects have significantly influenced the phenolics and flavonoids content in the leaf, stem and root of O. stamineus plant. For the bioactive concentration, the leaf, stem and root was significantly increased when treated for 4 week of water stress. The enzyme activity reveals that the cinnamic acid 4-hydroxylase activity increased when the plant stressed for four weeks. Next experiment aimed to identify the effects of nitrogen stress at different levels on bioactive concentration of O. stamineus leaf, stem and root. They were consisted of 0 N kg/ha (high N stress), 110 N kg/ha (low N stress), 170 N kg/ha (medium N stress) and 250 N kg/ha (control). The phenolics and flavonoids content for the plant was significantly affected when the plant imposed with medium N stress but the N stress had not influenced the antioxidant capacity of the plant. The N stress also not significantly affects the bioactive concentration in leaf, stem and root of O. stamineus plant. The last experiment was to determine the effects of water and nitrogen stresses at different levels on bioactive concentration of O. stamineus plant.