Effect of Pre formormospora indica and Foliar Application of Salicylic Acid on morphological characteristics and antioxidant enzymes of thyme irrigation cut-off stress

In order to investigate the effect of Piriformospora indica and different levels of salicylic acid on morphological characteristics and activity of antioxidant enzymes of thyme (Thymus vulgaris L.) irrigation cut-off stress, an experiment has been conducted in the water year 2016. It has employed a split factorial experiment based on randomized complete block design with four replications in the research farm of Dehloran Agricultural Research Center. The treatments are consisted of four levels of salicylic acid (0, 150, 300, and 600 μm) as foliar application and a mycorrhiza fungus agent at two levels of inoculation and non-inoculation and irrigation cut-off stress at three levels (irrigation at 90%, 50%, and 30% filed capacity). The results of this study show that with increasing irrigation cut-off stress up to 30% filed capacity plant height, total weight of shoot, number of leaves, colonization percentage, and the enzymes Catalase and Peroxidase have decreased. Inoculation and treatment with salicylic acid up to a concentration of 300 μM could significantly reduce the destructive effects of irrigation cut-off stress on these traits. However, increasing the concentration of salicylic acid to the level of 600 μM intensifies the effects of irrigation cut-off stress, preventing the positive effects of the fungus.