Increase of growth parameters, pigmentation and some primary compounds in Lepidium sativum L. seedlings under salinity stress using β-carotene and Gallic acid

Plants pre-treatment with various chemicals has often been used to diminish salinity stress impact on plants. In the present study, we used foliar spray of two antioxidant compounds (β -carotene and gallic acid) before the stress, to study interactive effect of antioxidants and salinity stress in seedlings of Lepidium sativum L. Our results showed growth indices, relative water content (RWC), chlorophyll a, chlorophyll b and chlorophyll a/b were negatively affected by 25 mM NaCl. The results obtained in the present study showed the beneficial effects of the pre-treatments of two antioxidants in of Lepidium sativum L. seedling under non salinity stress condition with respect to increasing root dry weight, RWC, photosynthetic pigments and the content of carbohydrate. The results suggested that foliar spray of β -carotene and gallic acid could considerably diminish NaCl-caused stress on Lepidium sativum L. seedlings, probably due to higher accumulation of plant biomass, photosynthetic pigments, RWC and carbohydrate content, as well as significant reduction of H2O2 and malondialdehyde (MDA) content. Collectively, it could be concluded that, the accumulation of osmotic metabolites and the intensification antioxidant systems during β -carotene and gallic acid -mediated pretreatments can diminish the deleterious effects of reactive oxygen species (ROS) induced by NaCl stress through preventing the lipid peroxidation and scavenging cytotoxic H2O2. Therefore, usage of antioxidant compounds as a pretreatment under salinity stress may be advantageous for increasing biomass and osmotic adjustment in Lepidium sativum L. seedlings