ACTIVITY AND MECHANISM OF ASCOPHYLLUM NODOSUM EXTRACT INDUCED SALINITY TOLERANCE IN TOMATO

Abstract

Salinity affects crop production worldwide. Ascophyllum nodosum, a brown marine alga, has been used for decades as a bio-stimulant to promote plant growth and impart tolerance to biotic and abiotic stresses. However, the mechanism(s) of the bio-stimulatory activity of A. nodosum extract (ANE) is not well understood. In vitro experiments were conducted to study the effect of the ethyl acetate fraction of ANE on two week old tomato plants (cv Scotia) grown under salinity stress (100 mM NaCl). The ethyl acetate fraction significantly improved seedling growth and development under salinity stress, i.e. the leaf area and root length of the treated plants improved while the in-planta sodium ion concentration decreased. Stimulated seedlings had higher catalase enzyme activity and recorded higher chlorophyll (chla, chlb and carotenoids) content than non-supplemented stressed plants. Moreover, when tested on four week old tomato plants in a greenhouse, ANE treated plants showed higher concentrations of potassium ions compared to controls. The results shed light on the complex nature of ANE.