Influence of light intensity and salinity on growth and antioxidant machinery of Thymus vulgaris L.
Abstract
Thymus vulgaris L. commonly known as Thyme or Garden Thyme, is important medicinal herb used for their wide ranging therapeutic properties. Agriculture practices of thyme plants influence their growth and biochemical composition. Here, we have evaluated the effects of two production systems and irrigation with saline water on growth, physiological characteristics and antioxidant capacity of T. vulgaris. Two levels of salinity stress 50 and 150 mM were applied for 2 and 4 weeks under shade enclosure or open field. The results showed that NaCltreated plants grown in shade enclosure showed reduced total dry weight and relative water content, photosynthetic characteristics and leaf pigments when compared to full sunny conditions. However, the shade conditions enhanced glucose and fructose accumulation mainly after a short period of NaCl stressapplication. The reduction of Ca2 and K was lower in NaClstressed plants grown under openfield conditions. Besides, under sunny conditions, plants showed significant increase in malondialdehyde MDA and H2O2 contents. Our resultsdemonstrated that these plants in open field have higher contents of reduced ascorbate ASC and reduced glutathione GSH than plants grown in shade enclosure, which could be related to enhanced activity of APX and GR. An increase in superoxide dismutase SOD and catalase CAT activity was also recorded. Moreover, activities of dehydroascorbate reductase DHAR, monodehydroascorbate reductase MDH
