Foliar spray of commercial seaweed and amino acid-derived biostimulants promoted phytoremediation potential and salinity stress tolerance in halophytic grass, .

Plants pretreatment with various chemicals has often been used to diminish salinity stress impact on plants. An experiment was carried out to determine the effect of foliar spray of two commercially available biostimulants (Algabon [0.5 g/l] and Bonamid [2 g/l]) on the growth and tolerance of halophytic grass, under non-salinity condition (NSC) and salinity condition (SC). The greenhouse experiment was set up in a completely randomized design with three treatments repeated three times. Our results showed that biomass, leaf relative water content, chlorophyll content, K content, K/Na ratio, and protein and N contents were all negatively affected by 300 mM NaCl. The results obtained in the present study showed the beneficial effects of the pretreatments of two biostimulants on seedlings under non-salinity stress conditions with respect to increasing plant biomass, photosynthetic pigments, K content, the content of proteins, and nitrogen percentage. The results suggested that foliar spray of Bonamid could partly diminish NaCl-caused stress on seedlings, probably due to higher accumulation of shoot biomass, photosynthetic pigments, K/Na ratio, protein and N contents, phytoremediation potential, as well as upregulation of Na/H antiporters located in plasma membranes and vacuoles. The highest phytoremediation potential (PP) of shoots and total biomass was detected in the plants sprayed with Bonamid by 50.8 and 42.7% respectively, relative to that in salinity-stressed control plants. Interestingly, foliar spray with two biostimulants decreased osmoprotectants and antioxidant compounds content of shoots under salinity stress conditions. Collectively, it could be concluded that a noticeable feature of pretreatment of seedlings with Algabon and Bonamid is the increase in growth under NSC, whereas under SC only pretreated plants with amino acid-derived biostimulant (Bonamid) can (partly) diminish the NaCl-induced deleterious effects in seedlings through the compartmentalization of salts in vacuoles (by upregulation of Na/H antiporters).