Effects of Exogenous Application of Ascorbic Acid and Salicylic Acid on Biochemical Characteristics of Zinnia (Zinnia elegans cv. Dreamland) under salinity stress

To investigate the effects of exogenous application of ascorbic acid and salicylic acid on some biochemical characteristics of Zinnia (Zinnia elegans cv. Dreamland)¡ an experiment was conducted at research greenhouse of Faculty of Agriculture¡ Lorestan University¡ Iran in 2014. The experiment was done factorially based on a completely randomized design with four replications. Factor A was salinity with four levels (0¡ 30¡ 60 and 90 mM NaCl) and factor B was foliar application with three levels (water as a control¡ 1 mM ascorbic acid and 1 mM salicylic acid). Zinnia seeds were directly planted in pots¡ and after plant establishment¡ NaCl treatments were applied through irrigation and foliar application was done weekly. The results showed that with increasing salinity¡ catalase (CAT)¡ peroxidase (POD) and ascorbate peroxidase (APX) activity¡ proline and malondialdehyde (MDA) content increased. As well as¡ chlorophyll content decreased with increasing salinity. Foliar application of ascorbic acid and salicylic acid increased antioxidant activity¡ proline and chlorophyll content¡ and decreased MDA in plants treated with NaCl¡ compared with control plants. According to the results¡ foliar application of ascorbic acid and salicylic acid could effectively increase plant survival and growth under salinity stress through preventing the negative effects of free radicals¡ increasing antioxidants activity¡ photosynthetic pigments and osmolytes¡ and reducing lipid peroxidation and caused better survival of plants under salinity stress.