Arginine and salinity stress affect morphology and metabolism of Indian borage (Plectranthus amboinicus lour.)

Abstract

Essential oil of Indian borage has different activities such as anti-bacterial and anti-malarial. Salinity stress has harmful effects on the productivity of aromatic plants. This study aimed decrease the harmful effect of sodium chloride (NaCl) on Indian borage plants by adapting them to salinity stress through the use of arginine. Plants were exposed to NaCl (0, 2 and 4 g/L) and/or arginine (0, 150 and 300 mg/L). Morphological characters (leaf area, total fresh and dry herbs as well as total fresh and dry roots), essential oil composition, photosynthetic pigments, proline, soluble sugars, crude protein, nutrients (NPK), antioxidant enzymes activities and protein banding patterns of Indian borage plants were evaluated. Obtained results were statistically analyzed using 2-way analysis of variance. Salinity treatments decreased morphological characters, photosynthetic pigments, crude protein and nutrient contents. Salinity promoted the accumulation of essential oil and its major constituents (carvacrol, thymol, γ-terpinene and limonene), proline, soluble sugars and the activities of antioxidant enzymes. Plants treated with salinity x arginine resulted in higher values of all growth characters and chemical composition than those treated with salinity only. On the other hand, salinity x arginine produced various changes in the number of bands. It may be concluded that application of arginine resulted in positive increases in growth, yield and chemical constituents of Indian borage under NaCl stress. So this study indicated that arginine resulted in a reduction of the hazards effect of salt stress.