Seaweed extract treatment enhances vegetative growth and antioxidant parameters in water stressed Salvia officinalis L.

The effect of seaweed extract (SWE) of Fucus spiralis (macroalgae) on tolerance of sage plants (Salvia officinalis) cultured under water deficit was studied. Plants were cultivated under three levels of water deficit: without stress (WS), moderate water deficit (MWD), severe water deficit (SWD), treated with SWE. SWE enhanced vegetative growth in sage with or without stress. The maximal shoot length was observed with application of 25% Fucus spiralis extract as well as leaf number. Treatments by SWE at 25% and 50% enhanced leaf area under MWD compared to control. The lipid peroxidation was low in stressed plants treated with SWE at 50%. Total phenolic content was increased in sage plants treated with 25% SWE under different growth conditions WS, MWD, and SWD. The highest total phenolic content was attained with the application of 25% F. spiralis extract in sage plant WS and subjected to drought stress (MWD). There was a significant enhancement of glycine betaine content (GB) but the response after application of SWE was variable. Drought stress had no significant effect on ascorbate peroxidase (APX) activity; however, plants treated by SWE at 50% and 75% increased this activity and reached 3.2 UE min^-1 mg protein^-1. Catalase activity (CAT) as well as superoxide dismutase activity (SOD) increased under drought stress; but these activities decreased after treatment by 50% SWE. The enhancements of antioxidant activity by SWE contribute to protection against peroxidation of lipids and reduce the severity of water deficit on sage plants.