Effects of salicylic acid foliar application on morpho-physiological traits of purslane (Portulaca olaracea L.) under salinity stress conditions

Purslane, Portulaca olaracea, is an annual plant used as potherb and traditional medicine. A factorial experiment was carried out to investigate the effects of different levels of salicylic acid (0.0, 0.5 and 1.0 mM) on growth characteristics and photosynthetic pigments of purslane under salinity stress (0.0, 40, and 80 mM). The treatment combinations were arranged in a completely randomized design with three replications. The measured traits were as follows: root and shoot dry weights, root and shoot lengths, leaf length and width, relative water content, number of leaves, total chlorophyll, chlorophyll a, b and carotenoids. Results showed that salinity had negative and decreasing effects on the majority of morphological traits and relative water content, whereas SA increased the growth and pigment contents of the purslane plant. For example, application of salicylic acid (1 mM) increased the content of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids from 0.43, 0.23, 0.65 and 4.49 mg/g under normal condition to 0.65, 0.46, 1.11 and 8.45 mg/g under saline condition, respectively. In conclusion, application of SA as a foliar agent improved the detrimental effects of salinity stress.