Seed priming with strigolactone GR24 develops tolerance toward salinity in ajwain (Trachyspermum ammi L.) by improving mineral nutrient contents and yield

Soil salinization limits the crop yield. Strigolactone GR24 is a plant growth regulator regulating environmental responses and enables the plant to tolerate stress by modulating morphology and physiology. Ajwain is a medicinal crop as well as a seed spice. The current experiment was designed to inspect the possible potential of GR24 as seed priming in mitigating the disastrous consequences of salinity in ajwain. Two ajwain populations, one from University of Agriculture, Faisalabad and the other from Peshawar were used for this study. Pre-sowing seed treatments (0, water-soaked, 0.001, 0.01, and 0.1 mg/L GR24) were given for 3 h. Salt stress at 100 mM NaCl was applied after 77 days of seed sowing. Salt stress reduced the yield and disturbed the distribution of ions in ajwain plants. The GR24 seed priming inhibited shoot Na+ uptake (33.81%), increased Ca2+ uptake and use efficiency (71.41%, 37.24%), K+ uptake and use efficiency (72.13%, 31.25%) and yield parameters including umbels/plant (31.22%), total seed weight (165%), and total number of seeds per plant (16.45%). Faisalabad population exhibited more umbels per plant and 1000 seed weight while Peshawar population accumulated less shoot Na+. Of different levels used for seed soaking, GR24 at 0.1 mg/L more effectively enabled the plant to adjust with elevated salt levels in the soil.