Presoaking application of propolis and maize grain extracts alleviates salinity stress in common bean (Phaseolus vulgaris L.)

• PE and MGE alleviated the adverse effects of NaCl-salinity.
• MGE-presoaked bean seedlings had the higher growth under NaCl-salinity.
• MGE-presoaked bean seedlings had the higher hormonal content under NaCl-salinity.
• PE and MGE maintained the aqueous status of seedlings under NaCl-stress.
• MGE and PE supported the antioxidant system to tolerate salinity.

Presoaking application of propolis extract (PE) or maize grain extract (MGE) for bean seeds to improve their germination and growth under 100 mM NaCl stress was investigated. The potential effects of these extracts on seed germination, seedling growth, dehydration tolerance, antioxidant system and the concentrations of some osmoprotectant molecules and phytohormones were evaluated. PE or MGE alleviated the adverse effects of NaCl-stress to varying degrees. Despite the preference for MGE, soaking seeds in either extract, prior to germination and growth under NaCl-salinity, increased the seed germination percentage, seedling growth, the cell membrane stability index, the relative water content, the concentrations of free proline, total free amino acids, total soluble sugars, indole-3-acetic acid (IAA) and gibberellic acid (GA3), and the activity of the antioxidant system, while it reduced lipid peroxidation, electrolyte leakage and abscisic acid (ABA) compared to soaking seeds in distilled water. These results are important as the potential of MGE or PE to alleviate the harmful effects of NaCl stress offers an opportunity to increase the resistance of common bean plants to growth under saline conditions.