β-Aminobutyric Acid Raises Salt Tolerance and Reorganises Some Physiological Characters in Calendula officinalis L. Plant

Salt stress is one of the main factors limiting plant growth and yield globally. Seed priming technique with different chemicals including β-aminobutyric acid (BABA) is found to be effective in enhancing plant growth and development under biotic and abiotic stresses. Scarce reports have been found about BABA seed priming in medicinal plants under stress conditions; however, several studies have been conducted on other crops but have not made an in-depth study to investigate biochemical and physiological changes. In current study the shoot growth, relative water content (RWC), chlorophyll content, stomatal conductance, nutrient content (N, P, K, Na and Cl), proline, malondialdehyde (MDA), hydrogen peroxide (H2O2) content, antioxidants enzymes (CAT, SOD and POD), membrane stability index (MSI), total phenolic and flavonoids contents lipid peroxidation and membrane permeability were investigated in Calendula officinalis L. leaves due to BABA seed priming and/or salt stress treatment. Salt stress treatment significantly reduced the growth characters, inflorescence number as well as its fresh and dry weights, N, P and K contents in leaves, RWC, chlorophyll content, stomatal conductance, MSI and total phenolic and flavonoids contents of pot marigold. However, proline content, MDA accumulation, H2O2 content and antioxidant enzyme activity (CAT, SOD and POD) were increased due to salt stress. On the other hand, seed priming with BABA significantly improved the growth characters, inflorescence attributes and the previously mentioned physiological and biochemical parameters investigated relative to the control. Applying seed priming under salt stress conditions significantly mitigated the negative effects of salinity and enhanced the growth and productivity of pot marigold and therefore was suggested to be an effective technique prior to cultivation.