Combined effect of hormonal priming and salt treatments on germination percentage and antioxidant activities in lettuce seedlings

Abstract

Hormonal priming is a pre-sowing treatment that improves seed germination performance and stress tolerance. To understand the physiology of hormonal priming and its association with post priming stress tolerance, we investigated the effect of hormonal priming with increasing gibberellic acid (GA₃) concentrations (0, 3, 4.5 and 6 mM) on seedling growth and antioxidant system in lettuce. Germination percentage was higher in lettuce seedlings derived from primed seeds. Radicle and hypocotyl length and dry weight were reduced by salt treatment to a greater extent in non-primed than in primed seeds. Hormonal priming with 4.5 mM GA₃ induced the most dramatic decreases in electrolyte leakage (EL) and malondialdehyde (MDA) levels. NaCl increased catalase (CAT) activity in primed and non-primed seeds. The total ascorbate level remained constant in both primed and non-primed seeds under NaCl constraint. These results suggest that hormonal priming might have increased the salt tolerance of lettuce seeds through enhancing the activities of antioxidant enzymes and reducing the membrane damage as estimated using EL and MDA biomarkers.

Key words: Ascorbate, germination, hormonal priming, lettuce, salinity.