Physiological Performance of Dill Plants Affected by Seed Pretreatments Under Salt Stress

The impacts of seed polymer coating and priming with gibberellic acid (GA3: 1 mM) and salicylic acid (SA: 1 mM) on dill plants (Anethum graveolens L.) were examined under different levels of salinity (non-saline, 4, 8 and 12 dS/m NaCl). The sodium content, H2O2 generation, malondialdehyde (MDA), ascorbic acid and α‑tocopherol and endogenous SA were increased, while potassium, calcium, magnesium, K+/Na+ ratio, membrane stability (MSI) and endogenous GA3 were decreased with increasing salinity. Total phenol content and antioxidant activity were elevated up to 8 dS/m and thereafter considerably declined. A reduction in seed yield, essential oil percentage and yield was occurred under severe salinity. Seed priming with GA3 and SA reduced sodium and oxidative stress, but enhanced nutrient content, MSI and endogenous GA3 and SA. Antioxidants, seed and essential oil production were improved in response to GA3 and particularly SA. The highest sodium and oxidative stress and the lowest nutrients, MSI, antioxidants, endogenous GA3 and SA, and seed and essential oil yields under different levels of salinity were recorded for plants from polymer-coated seeds. Therefore, seed priming with GA3 and particularly SA could be used as a potential tool to improve antioxidative activity and essential oil production in dill plants under salt stress.