The effects of amino acid fertilizers spraying on photosynthetic pigments and antioxidant enzymes of wheat (Triticum aestivum L.) under salinity stress

Abstract

To understand the effects of amino acid fertilizers spraying on some physiological traits of wheat (Triticum aestivum L.) under salinity stress, an experiment were conducted in a factorial arrangement based completely randomized design with three replicates. The activity of six amino acid fertilizers, including: Kadostim, Phosphotrn, Aminolephorte, Hyomiphorte and fish emulsion along with a control was analyzed at three salinity levels (0, 40, 80 mM NaCl). The seedlings of wheat was evaluated after a 14 days treatment, then, catalase (CAT) and peroxidase (POD) were subjected as antioxidant enzymes and the adaptability of photosynthetic pigments (chlorophyll a, b, a+b and carotenoids) were determined. According to the results, the effect between salinity levels and amino acid fertilizers were no significant for neither photosynthetic nor antioxidant enzymes, although photosynthetic pigments decreased due to salt stress. The maximum values of chlorophyll a, b, and a+b (2.258, 1.962 and 4.272 mg/gr respectively) were obtained by the interaction between fish emulsion fertilizer and 0 mM NaCl. The results showed that total carotenoids reached the highest value (2.747 mg/gr) after spraying of Kadotism fertilizer in control plants. Furthermore amino acid treatments significantly increased pigments content of seedlings under both normal and salinity conditions. The results indicated that the activity of CAT and POD were not significantly changed in leaves, when they were subjected to salt stress. The maximum activity of CAT was recorded in Hyomiphorte fertilizer at 80 mM NaCl. Since CAT activity increased by amino acid application in this cultivar, it had more efficient role compared with POD because POD's activity had no clear trend neither by fertilizers application nor salinity levels. These results clearly indicated that amino acid can reduce the harmful effects of reactive oxygen species (ROS) and improves wheat seedling resistant under salt stress conditions.