Modulations Induced by Seed Priming of Strigolactone (GR24) in Morpho-Physiological and Biochemical Attributes of Ajwain (Trachyspermum ammi L.) Under Salt Stress

Salinity affects the plant morphology, physiology, and yield. Strigolactone is a phytohormone regulating the plant architecture under stress conditions. The strigolactone GR24 is a synthetic analogue, involved in plant tolerance toward abiotic stresses. Ajwain is medicinal plant and a spice, used in a number of medicines because of its various pharmacological activities. The present investigation was executed to examine the role of strigolactone GR24 on morphological and biochemical characters of ajwain plants exposed to salinity stress. Faisalabad and Peshawar populations of ajwain were used in this trial. Ajwain seeds were treated with varying strigolactone levels (dry control, control, 0.001, 0.01, 0.1 mg/L) for 3 h before sowing. Salt application (Control and 100 mM NaCl) was given after eleven weeks of seed sowing. Salinity application reduced the shoot length, shoot fresh weight, enhanced the activity of peroxidase and proline. The pre-sowing GR24 seed treatment escalated shoot fresh weight, activities of enzymatic antioxidants including superoxide dismutase, peroxidase, and catalase along with non-enzymatic antioxidants like total phenolics under salt stress. Compatible solutes like free proline and glycinebetaine were also enhanced by GR24 treatment during salinity application. The concentration of MDA was decreased in plants raised from GR24-treated seeds. Overall, ajwain plants raised from seeds collected from Faisalabad were better with respect to enzymatic antioxidants, whereas ajwain plants raised from seeds collected from Peshawar were promising regarding accumulation of organic osmotic.