Effect of seed priming on salinity tolerance of (Cassia fistula L.) at seed germination and seedling growth stages using digital image analysis

Seed germination is one of the most important and basic stages of plant growth and development so it has great importance and effect on other stages of its growth. Cassia is a plant from the legume family and has many medicinal properties. Cassia propagation is done by seeds, but no study and report on the tolerance of these seeds to salinity stress in the country have been presented yet. Two factorial experiments were performed in a completely randomized design at the Seed Technology Laboratory of Agricultural Sciences and Natural Resources University of Khuzestan. In the first experiment, the effect of hormone priming treatment with gibberellin, halopriming with potassium nitrate, and hydro priming on Cassia seed germination was investigated. The results of this experiment showed that the highest seed vigor was obtained in the treatment of 50 mg/l gibberellin for 12 hours of priming. After selecting the best treatment (gibberellin 50 mg/l for 12 hours), germination characteristics of primed seeds compared with no primed seeds under salinity stress (0, 4, 8, 14, 16, and 20 dS/m). The results showed that seed tolerance to salinity stress at the germination stage increased significantly with seed priming. The highest seed vigor was observed in priming treatment at no salinity stress condition (339.89) while the lowest seed vigor of primed treatment was observed in 20 dS/m. Unprimed seeds could not withstand salinity stress beyond 4 dS/m.