The effect of different concentrations of salicylic acid on physiological parameters in pepper (Capsicum annuum L.)

Salicylic acid (SA) is an antioxidant which has been used in recent years to increases the resistance of plants to deal with stresses. In this study 5 weeks after germination, different concentrations (0.1, 0.7, 1.5, 3, 6 and 9 mM) of salicylic acid application were investigated on germination, shoot and root length, anthocyanin, reduced sugars, protein, ascorbic acid, dehydroascorbic acid and proline in pepper. The results showed that under experimental conditions concentrations of 0.1, 0.7, 1.5 and 3 mM of SA increased germination, shoot and root length, but 6 and 9 mM of SA concentrations decreased germination percent, shoot and root length. Concentrations of 1.5 and 3 mM of SA decreased ascorbic acid and dehydroascorbic acid content, but concentrations 6 and 9 mM of SA increased ascorbic acid and dehydroascorbic acid content in the leaf of pepper plant. Concentrations of 1.5 and 3 mM SA caused significant increase in sugars and protein content in treated leaf but 6 and 9 mM of concentrations SA decreased sugars and protein content. Also, other research findings showed that under experimental conditions, different concentrations (0.7, 1.5, 3, 6 and 9 mM) of SA increased content of anthocyanin and proline in the leaf of pepper plant . In general, treatment of SA low and height concentrations has positive and negative effects on plant growth on the growth of the pepper plant, respectively.