Basil (Ocimum basilicum L.) is uasually used in traditional medicine and contains a wide range of essential oils rich in phenolic compounds and a wide array of other natural products including polyphenols such as flavonoids and anthocyanins. This plant is a relatively sensitive plant to salinity. Salinity is one of the most important factors that limits plant growth and development. Ascorbic acid (ASA) and silicon (Si) as the second most abundant mineral element in the soil have ability to alleviate the adverse effects of salinity on plant. In order to study the effect of salinity stress in some morphological parameters and pigment characters (Chl.a , Chl.b, Chl. a/b, total Chl. and carotenoid) in a greenhouse experiment was conducted in a 3-replicant completely randomized factorial design. The seedlings were treated with Si (0, 1 and 2 mM) and ASA (0, 50 and 100 mM) concentrations under salinity stress (0, 100 and 200 mM NaCl). The results showed that salinity significantly decreased pigment parameters, dry weight and length of roots/shoots and leaf area (LA) of Ocimum basilicum. Results of analysis showed that this morphological parameters and leaf area specially and chlorophyll a and b content were positively affected by different concentration of ASA and Si applications. Regarding Our survay, it provides strong support to the hypothesis that exogenous application of ascorbic acid and silicium reduces the harmful effects of salinity and so increases the resistance of Ocimum basilicum to salinity by improving growth parameters (e.g. root dry weight and leaf area) and pigment contents.

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