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

Abstract

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, Pucccinellia distans 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 P. distans 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 P. distans 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 P. distans 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 P. distans seedlings through the compartmentalization of salts in vacuoles (by upregulation of Na(+)/H(+) antiporters). We report for the first time that foliar spray of two commercially biostimulants (Algabon(®) and Bonamid(®)) could improve growth and phytoremediation potential of halophytic grass, Pucccinellia distans under the subsequent salinity stress. We also illustrated the impact of biostimulants on the mechanisms behind the improvement in tolerance of P. distans to the following salinity in regard to K(+)/Na(+) ratio, protein and N contents, antioxidant capacity, osmoprotectant compounds, and the upregulation of Na(+)/H(+) antiporters located in plasma membranes and vacuoles. eng