The Effect of Salicylic Acid On Photosynthetic Characteristics, Growth Attributes, and Some Antioxidant Enzymes On Parsley (Petroselinum crispum L.) Under Salinity Stress

Parsley (Petroselinum crispum L.) is widely used in food, medicine, cosmetics, and pharmaceutical industries. This research was conducted to determine the effect of six different irrigation water salinities (S-1 = 0.38, S-2 = 1.5, S-3 = 2.5, S-4 = 4, S-5 = 7 and S-6 = 10 dS m(-1)) and two levels of foliar application of salicylic acid (SA(1) = 0 mM and SA(2) = 2 mM) on yield, yield parameters, and antioxidant enzyme activity of parsley. Increasing salinity reduced the fresh weight, plant height, evapotranspiration, chlorophyll content, and stomatal conductance (g(s)), whereas foliar salicylic acid application positively affected the vegetative growth parameters. Salinity and foliar application of salicylic acid significantly affected total protein, peroxidase (POD), and glutathione S-transferase (GST) activities. The POD and GST activities increased as salinity increased to 4.0 dS m(-1) and 2.50 dS m(-1), respectively. Fresh weight highly correlated with stomatal conductance (g(s)) (r = 0.725**), chlorophyll content (r = 0.366*) and GST (r = 0.646**). The application of 2 mM salicylic acid to parsley under salinity stress decreased the negative effect on growth and increased its fresh weight.